AS Extended Writing Practice
272 minutes
266 marks
Q1.
A fluorescent light tube contains mercury vapour at low pressure. The tube is coated on
the inside, and contains two electrodes.
(a)
Explain why the mercury vapour is at a low pressure.
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(1)
(b)
Explain the purpose of the coating on the inside of the tube.
You may be awarded marks for the quality of written communication in your answer.
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(Total 4 marks)
Q2.
Electromagnetic waves and electrons have properties of both particles and waves.Explain
what evidence there is to support this statement.Experimental details are not required.
You may be awarded marks for the quality of written communication in your answer.
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(Total 6 marks)
Q3.
Figure 1 shows the energy level diagram of a hydrogen atom. Its associated spectrum is
shown in Figure 2.
The transition labelled A in Figure 1 gives the spectral line labelled B in Figure 2.
Figure 1
Figure 2
hydrogen spectrum showing some of the main spectral lines
(a)
(i)
Show that the frequency of spectral line B is about 4.6 × 1014 Hz.
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(ii)
Calculate the wavelength represented by line B.
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(3)
(b)
The hydrogen atom is excited and its electron moves to level 4.
(i)
How many different wavelengths of electromagnetic radiation may be emitted as the
atom returns to its ground state?
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(ii)
Calculate the energy, in eV, of the longest wavelength of electromagnetic radiation
emitted during this process.
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(2)
(c)
In a fluorescent tube, explain how the mercury vapour and the coating of its inner surface
contribute to the production of visible light. You may be awarded additional marks to those
shown in brackets for the quality of written communication in your answer.
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(3)
(Total 8 marks)
Q4.
(a) When monochromatic light is incident on a metal plate, electrons are emitted only
when the frequency of light exceeds a certain frequency.Explain in terms of energy, why
this threshold frequency exists and why a photon theory of light provides a better
explanation of the photoelectric effect than a wave theory of light.The quality of your
written answer will be assessed in this question.
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(b)
A gold surface is illuminated with monochromatic ultra violet light of frequency
2.10 × 1015 Hz. The maximum kinetic energy of an emitted photoelectron is
6.20 × 10–19 J.
Calculate
(i)
the energy, in J, of the incident photon,
energy = ..................................J
(ii)
the work function of gold,
work function = ....................................
(5)
(Total 12 marks)
Q5.
When light of a certain frequency is shone on a particular metal surface, electrons are
emitted with a range of kinetic energies.
(a)
Explain
•
in terms of photons why electrons are released from the metal surface, and
•
why the kinetic energy of the emitted electrons varies upto a maximum value.
The quality of your written communication will be assessed in this question.
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(6)
(b)
The graph below shows how the maximum kinetic energy of the electrons varies with the
frequency of the light shining on the metal surface.
(i)
On the graph mark the threshold frequency and label it f0.
(1)
(ii)
On the graph draw a line for a metal which has a higher threshold frequency.
(2)
(iii)
State what is represented by the gradient of the graph.
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(1)
(c)
The threshold frequency of a particular metal surface is 5.6 × 1014 Hz. Calculate the
maximum kinetic energy of emitted electrons if the frequency of the light striking the metal
surface is double the threshold frequency.
answer = .................................. J
(3)
(Total 13 marks)
Q6.
A student wishes to collect data so he can plot the I-V curve for a semiconductor diode.
(a)
(i)
Draw a suitable diagram of the circuit that would enable the student to collect this
data.
(3)
(ii)
Describe the procedure the student would follow in order to obtain an I-V curve for
the semiconductor diode.
The quality of your written communication will be assessed in this question.
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(b)
The diagram below shows an arrangement of a semiconducting diode and two resistors.
A 12.0 V battery is connected with its positive terminal to A and negative terminal to B.
(i)
Calculate the current in the 8.0 Ω resistor
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answer .................................. A
(2)
(ii)
Calculate the current in the 4.0 Ω resistor if the p.d. across the diode, when in
forward bias, is 0.65 V expressing your answer to an appropriate number of
significant figures.
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answer ................................... A
(3)
(Total 14 marks)
Q7.
Electrons with a range of kinetic energies strike atoms of a particular element which are in
their ground state. As a result of these collisions photons of various frequencies are emitted by
some of the atoms.
(a)
Explain what is meant by the ground state of an atom and describe the process that is
taking place in the atoms emitting photons.
The quality of your written communication will be assessed in this question.
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(b)
The table below shows how the kinetic energies of electrons with different incident
energies may change after collisions with atoms.
(i)
kinetic energy of electron
before collision/eV
kinetic energy of electron
after collision/eV
First electron
5.5
5.5
Second
electron
9.0
1.0
Explain why one of the electrons loses energy while the other does not.
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(2)
(ii)
Convert the energy of 9.0 eV into joules
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(iii)
Calculate the maximum frequency of the photon emitted when the 9.0 ev electron
collides with an atom.
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answer ............................. Hz
(3)
(Total 13 marks)
Q8.(a)
A sample of conducting putty is rolled into a cylinder which is 6.0 × 10–2 m long and has a
radius of 1.2 × 10–2 m.
resistivity of the putty = 4.0 × 10–3 Ωm.
Calculate the resistance between the ends of the cylinder of conducting putty.
Your answer should be given to an appropriate number of significant figures.
answer = ...................................... Ω
(4)
(b)
Given the original cylinder of the conducting putty described in part (a), describe how you
would use a voltmeter, ammeter and other standard laboratory equipment to determine a
value for the resistivity of the putty.
Your description should include
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a labelled circuit diagram,
details of the measurements you would make,
an account of how you would use your measurements to determine the result,
details of how to improve the precision of your measurements.
The quality of your written communication will be assessed in this question.
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(8)
(Total 12 marks)
Q9.
(a) A student wishes to investigate how the resistance of a thermistor changes with
temperature.
(i)
Draw a labelled diagram of a suitable circuit that would enable the student to
measure the resistance of the thermistor.
(2)
(ii)
Describe the procedure the student would follow in order to obtain accurate and
reliable measurements of the resistance of the thermistor at different temperatures.
The quality of your written communication will be assessed in this question.
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(6)
(b)
The diagram below shows a thermistor connected in series with a resistor, R, and battery
of emf 6.0 V and negligible internal resistance.
When the temperature is 50 °C the resistance of the thermistor is 1.2 kΩ. The voltmeter
connected across R reads 1.6V.
(i)
Calculate the pd across the thermistor.
answer = ...................................... V
(1)
(ii)
Calculate the current in the circuit.
answer = ...................................... A
(1)
(iii)
Calculate the resistance of R quoting your answer to an appropriate number of
significant figures.
answer = ..................................... Ω
(2)
(c)
State and explain the effect on the voltmeter reading if the internal resistance of the
battery in the circuit in part (b) was not negligible.
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(2)
(Total 14 marks)
Q10.
(a) Line spectra were observed before they could be explained by theory. We now know
that photons of characteristic frequency are emitted when the vapour of an element is
bombarded by energetic electrons. The spectrum of the light emitted contains lines, each
of a definite wavelength.
Explain how
•
the bombarding electrons cause the atoms of the vapour to emit photons
•
the existence of a spectrum consisting of lines of a definite frequency supports the
view that atoms have discrete energy levels.
The quality of your written communication will be assessed in this question.
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(6)
(b)
The ionisation energy of a hydrogen atom is 13.6eV.
(i)
State what is meant by the ionisation energy of hydrogen.
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(2)
(ii)
Express the ionisation energy of hydrogen in joules, giving your answer to
anappropriate number of significant figures.
answer = ....................................... J
(3)
(Total 11 marks)
Q11.
(a) A student is given a piece of metal wire and asked to investigate how the resistance
of the wire changes between a temperature of 0 °C and 100 °C.
(i)
Draw a labelled diagram of a suitable arrangement that would enable the student to
carry out the experiment.
(3)
(ii)
Describe the procedure the student would follow in order to obtain accurate and
reliable measurements of the resistance of the wire at different temperatures
between 0 °C and 100 °C.
The quality of written communication will be assessed in your answer.
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(b)
A certain metal has a critical temperature of –268 °C (5 K). Explain what is meant by
critical temperature.
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(2)
(Total 11 marks)
Q12.
(a) An alternating current supply provides an output voltage of 12 V rms at a frequency
of 50 Hz. Describe how you would use an oscilloscope to check the accuracy of the rms
output voltage and the frequency of the supply.
The quality of your written communication will be assessed in your answer.
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(6)
(b)
The power supply in part (a) is connected to a 12 V 24 W lamp.
(i)
Calculate the rms current in the lamp.
answer = ...................................... A
(1)
(ii)
Calculate the peak current in the lamp.
answer = ...................................... A
(1)
(iii)
Calculate the peak power of the lamp.
answer = ...................................... W
(2)
(Total 10 marks)
Q13.An experiment can be performed to determine whether a particular component is an ohmic
conductor.
(a)
State what is meant by an ohmic conductor.
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(1)
(b)
(i)
Draw a suitable circuit diagram for such an experiment.
(2)
(ii)
For the circuit diagram you have drawn, describe a suitable experiment. Your
account should include details of:
•
what measurements you would take
•
how you would use your measurements
•
how you would reach a conclusion.
The quality of written communication will be assessed in your answer.
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(c)
(i)
State the principal property of a superconductor.
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(1)
(ii)
State what is meant by critical temperature.
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(iii)
Give one use of a superconductor.
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(1)
(Total 12 marks)
Q14.(a)
Hadrons and leptons are two groups of particles.Write an account of how particles are
placed into one or other of these two groups.Your account should include the following:
•
how the type of interaction is used to classify the particles
•
examples of each type of particle
•
details of any similarities between the two groups
•
details of how one group may be further sub-divided.
The quality of your written communication will be assessed in your answer.
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(b)
Every type of particle has a corresponding antiparticle.
(i)
Give one example of a particle and its corresponding antiparticle.
particle......................................................................................................
antiparticle..................................................................................................
(1)
(ii)
State one difference between this particle and its antiparticle.
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(1)
(Total 8 marks)
Q15.
(a)
State two requirements for two light sources to be coherent.
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(2)
(b)
Figure 1
Young’s fringes are produced on the screen from the monochromatic source by the
arrangement shown in Figure 1.Explain how this arrangement produces interference
fringes on the screen. In your answer, explain why slit S should be narrow and why slits
S1 and S2 act as coherent sources.The quality of your written answer will be assessed in
this question.
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(c)
The pattern on the screen may be represented as a graph of intensity against position on
the screen. The central fringe is shown on the graph in Figure 2. Complete this graph to
represent the rest of the pattern by drawing on Figure 2.
Figure 2
(2)
(Total 10 marks)
Q16.
(a)
State Hooke’s law.
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(2)
(b)
A student is asked to measure the mass of a rock sample using a steel spring, standard
masses and a metre rule. She measured the unstretched length of the spring and then set
up the arrangement shown in the diagram below.
(i)
Describe how you would use this arrangement to measure the mass of the rock
sample. State the measurements you would make and explain how you would use
the measurements to find the mass of the rock sample.
The quality of your written communication will be assessed in this question.
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(6)
(ii)
State and explain one modification you could make to the arrangement in the
diagram above to make it more stable.
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(2)
(Total 10 marks)
Q17.
A student investigated how the extension of a rubber cord varied with the force used to
extend it. She measured the extension for successive increases of the force and then for
successive decreases. The diagram below shows a graph of her results.
(a)
(i)
Give a reason why the graph shows the rubber cord does not obey Hooke’s law.
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(1)
(ii)
Give a reason why the graph shows the rubber cord does not exhibit plastic
behaviour.
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(1)
(iii)
What physical quantity is represented by the area shaded on the graph between the
loading curve and the extension axis?
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(1)
(b)
Describe, with the aid of a diagram, the procedure and the measurements you would
make to carry out this investigation.
The quality of your written answer will be assessed in this question.
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(Total 9 marks)
Q18.
A steel ball is released from rest above a cylinder of liquid, as shown in Figure 1. The ball
descends vertically in the air then in the liquid until it reaches the bottom of the cylinder.
Figure 1
(a)
The vertical distance from the bottom of the ball at the point where it is released to the
liquid surface is 0.16 m.
(i)
Calculate the time taken, t0, by the ball to fall to the liquid surface from the point
where it is released. Give your answer to an appropriate number of significant
figures.
answer................................. s
(3)
(ii)
Calculate the velocity, ν0, of the ball on reaching the liquid.
answer .................................. m s–1
(2)
(b)
Figure 2 below shows how the velocity of the ball changed after it was released.
Figure 2
Describe and explain how the acceleration of the ball changed after it entered the liquid
until it reached the bottom of the cylinder.
The quality of your written answer will be assessed in this question.
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(Total 11 marks)
Q19.
(a) Describe how to obtain, accurately by experiment, the data to determine the Young
modulus of a metal wire.
A space is provided for a labelled diagram.
The quality of your written answer will be assessed in this question.
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(b)
The diagram below is a plot of some results from an experiment in which a metal wire was
stretched.
(i)
Draw a best-fit line using the data points.
(1)
(ii)
Use your line to find the Young modulus of the metal, stating an appropriate unit.
answer = ......................................
(4)
(c)
After reaching a strain of 7.7 × 10–3, the wire is to be unloaded. On the diagram above,
sketch the line you would expect to obtain for this.
(1)
(Total 12 marks)
Q20.
The figure below shows a gymnast trampolining.
In travelling from her lowest position at A to her highest position at B, her centre of mass rises
4.2 m vertically. Her mass is 55 kg.
(a)
Calculate the increase in her gravitational potential energy when she ascends from
position A to position B.
answer = ................................... J
(2)
(b)
The gymnast descends from position B and regains contact with the trampoline when it is
in its unstretched position. At this position, her centre of mass is 3.2 m below its position
at B.
(i)
Calculate her kinetic energy at the instant she touches the unstretched trampoline.
answer = ................................... J
(1)
(ii)
Calculate her vertical speed at the same instant.
answer = ............................. m s–1
(2)
(c)
Draw an arrow on the figure above to show the force exerted on the gymnast by the
trampoline when she is in position A.
(1)
(d)
As she accelerates upwards again from position A, she is in contact with the trampoline
for a further 0.26 s. Calculate the average acceleration she would experience while she is
in contact with the trampoline, if she is to reach the same height as before.
answer = ............................. m s–2
(2)
(e)
On her next jump the gymnast decides to reach a height above position B. Describe and
explain, in terms of energy and work, the transformations that occur as she ascends from
her lowest position A until she reaches her new position above B.
The quality of your written communication will be assessed in this question.
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(Total 14 marks)
Q21.
The figure below shows a stationary wave on a string. The string is tied onto a thin metal
bar at A and fixed at B. A vibration generator causes the bar to oscillate at a chosen frequency.
Explain how a stationary wave is formed. Then describe the key features of the stationary wave
shown in the figure above.
The quality of your written answer will be assessed in this question.
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(Total 6 marks)
Q22.
A scientist is going to use a double-slit arrangement to carry out measurements in order to
determine the wavelength of light from a laser.
(a)
The scientist has a double slit of known separation. Describe the measurements that need
to be taken and explain how they are used to find the wavelength of the light. Discuss any
necessary safety precautions and how you would arrange the apparatus to improve
accuracy.
The quality of your written communication will be assessed in this question.
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(b)
In 1802 Thomas Young used candle light to observe the interference pattern from
twonarrow slits acting as coherent light sources.
Explain what is meant by coherent light sources.
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(c)
Sketch and label on the diagram below the arrangement that Young would have used
toobtain his interference pattern.
(2)
(d)
State two differences in the appearance of the pattern obtained with a laser and
thatproduced by a white light source such as a candle.
Difference 1 ..................................................................................................
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Difference 2 ..................................................................................................
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(2)
(e)
Explain how the wave theory of light accounts for the areas on the screen where
theintensity is a minimum.
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(Total 14 marks)
Q23.
(a) In an experiment, a narrow beam of white light from a filament lamp is directed at
normal incidence at a diffraction grating. Complete the diagram in the figure below to
show the light beams transmitted by the grating, showing the zero-order beam and the
first-order beams.
(3)
(b)
Light from a star is passed through the grating.
Explain how the appearance of the first-order beam can be used to deduce one piece of
information about the gases that make up the outer layers of the star.
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(c)
In an experiment, a laser is used with a diffraction grating of known number of lines per
mm to measure the wavelength of the laser light.
(i)
Draw a labelled diagram of a suitable arrangement to carry out this experiment.
(2)
(ii)
Describe the necessary procedure in order to obtain an accurate and reliable value
for the wavelength of the laser light.Your answer should include details of all the
measurements and necessary calculations.The quality of your written
communication will be assessed in your answer.
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...............................................................................................................
...............................................................................................................
...............................................................................................................
...............................................................................................................
(6)
(Total 13 marks)
Q24.Discuss the formation of stationary waves on a string or rope. Your account should include:
•
a labelled diagram of a stationary wave
•
the conditions necessary for stationary waves to form
•
a definition of the terms node and antinode
•
an explanation of how nodes and antinodes form.
The quality of written communication will be assessed in your answer.
(Total 6 marks)
Q25.A steel ball has a diameter of 2.2 × 10−2 m.
(a)
Calculate the weight of the steel ball. Give your answer to an appropriate number of
significant figures.
density of steel = 8100 kg m−3
weight ...........................................N
(4)
(b)
Figure 1 shows two identical steel balls dropped from rest into containers of oil.
Figure 1
(i)
Figure 2 shows the velocity-time graph for steel ball A.
Figure 2
Explain the shape of the graph in Figure 2. Your account should include
•
•
how the velocity and acceleration of the steel ball vary with time
reference to how Newton’s First and Second laws of motion apply in this
situation.
The quality of written communication will be assessed in your answer.
(6)
(ii)
On Figure 3, sketch the velocity-time graph you would expect to see for steel ball B.
Assume air resistance is negligible.
Figure 3
(3)
(Total 13 marks)
M1.
(a) there must be a large distance between collisions to allow electrons to gain enough
energy (1)[or the vapour must not completely absorb the electrons]
1
(b)
the mercury vapour emits ultra violet (radiation) (1)
the coating absorbs electromagnetic radiation/light from
the mercury (1)
emits longer wavelengths/lower frequencies
in the visible region (1)
max 3
QWC 2
[4]
M2.
electrons diffract [or high energy electron scattering] (1)
showing wave behaviour (1)
electrons are deflected in electric or magnetic fields (1)
showing particle behaviour (1)
interference of electromagnetic waves (1)
showing wave behaviour (1)
photoelectric effect (1)
showing particle behaviour (1)
max 6
QWC 2
[6]
M3.
(a)
(i)
(3.40-1.51 = 1.89)
ΔE= 1.89 × 1.60 × 10–19(J) (1)
(= 3.02 × 10–19(J))
(1)
(=4.56 × 1014Hz)
(ii)
(1)
(use of f = 4.6 × 1014 gives λ = 6.5 × 10–7m)
3
(b)
(i)
6 (wavelengths) (1)
(ii)
(1.51–0.85) = 0.66(eV) (1)
2
(c)
mercury vapour at low pressure is conducting (1)
atoms of mercury are excited by electron impact (1)
producing (mainly) ultra violet radiation (1)
which is absorbed/ excites the coating (1)
which, upon relaxing, produces visible light (1)
electrons cascade down energy levels (1)
3
[8]
M4.
(a) The marking scheme for this part of the question includes an
overall assessment for the quality of written communication.
There are no discrete marks for the assessment of written
communication but the quality of written communication will
be one of the criteria used to assign the answer to one of three levels.
Level
Descriptor
an answer will be expected to meet most of the criteria in the
level descriptor
Good 3
Mark
range
– answer supported by appropriate range of relevant points
– good use of information or ideas about physics, going
beyond those given in the question
– argument well structured with minimal repetition or
irrelevant points
6-7
– accurate and clear expression of ideas with only minor
errors of spelling, punctuation and grammar
Modest 2
– answer partially supported by relevant points
– good use of information or ideas about physics given in
the question but limited beyond this
– the argument shows some attempt at structure
3-5
– the ideas are expressed with reasonable clarity but with a
few errors of spelling, punctuation and grammar
Limited 1
– valid points but not clearly linked to an argument structure
– limited use of information or ideas about physics
0
– unstructured
1-2
0
– errors in spelling, punctuation and grammar or lack of
fluency
– incorrect, inappropriate or no response
physics points:
(b)
•
the energy of each photon/the light increases with frequency (1)
•
electrons need a minimum amount of energy to leave the metal (1)
•
the amount of energy required is equal to the work function (1)
•
(this suggests) the electrons are given energy in one discrete eventor one electron
interacts with one photon (1)
•
(so the) light energy is not spread out it is concentrated (intoquanta) (1)
•
the electron does not build up energy over time or photoelectricityoccurs
immediately light falls on the metal (1)
(i)
E = hf = 6.63 × 10–34 × 2.10 × 1015 = 1.39 × 10–18 (J) (1)
(ii)
= hf – Ek (1)
= 1.39 × 10–18 – 6.20 × 10–19
= 7.72 × 1019 J (1)
5
[12]
M5.
(a)
QWC
descriptor
mark
range
The candidate provides a comprehensive and logical
explanation which recognises that light consists of photons
of energy hf and that an electron at or near the metal
surface can only gain the energy of a single photon when it
interacts with a photon. In addition, the candidate should
recognise the significance of the work function (of the
metal) in this context in relation to the maximum kinetic
energy that an emitted electron can have. The candidate
should also provide some indication of why the kinetic
energy of an emitted electron may be less than the
maximum kinetic energy. Although the term ‘work function’
might not be defined or used, the candidate’s explanation
should clearly state that each electron needs a minimum
amount of energy to escape from the metal.
5-6
modest- The candidate provides a logical and coherent explanation
adequate which includes the key ideas including recognition that light
consists of photons of energy hf and that an electron at or
near the metal surface can only gain the energy of a single
photon when it interacts with a photon. In addition, the
candidate should be aware that each electron needs a
minimum amount of energy to escape from the metal. They
should appreciate that the kinetic energy of an emitted
electron is equal to the difference between the energy it
gains from a photon and the energy it needs (or uses) to
escape from the metal. However, the explanation may lack
a key element such as why the kinetic energy of the
emitted electrons varies.
3-4
goodexcellent
poorlimited
The candidate provides some correct ideas including
recognition that light consists of photons of energy hf and
that electrons in the metal (or at its surface) absorb
photons and thereby gain energy. Their ideas lack
coherence and they fail to recognise or use in their
explanation the key idea that one photon is absorbed by
one electron.
1-2
The explanations expected in a good answer should include most of the following
physics ideas
energy is needed to remove an electron from the surface
work function φ (of the metal) is the minimum energy needed byan electron to escape
from the surface
light consists of photons , each of energy E = hf
one photon is absorbed by one electron
an electron can escape (from the surface) if hf > φ
kinetic energy of an emitted electron cannot be greater than hf – φ
an electron below the surface needs to do work/uses energy to reachthe surface
kinetic energy of such an electron will be less than hf – φ
(b)
(i)
(ii)
parallel line, higher threshold frequency (1)(1)
(iii)
Planck’s constant (1)
4
(c)
(use of hf0 =
)
hf = 6.63 × 10–34 × 2 × 5.6 × 1014 (1)
= 3.7(1) × 10–19 J (1)
Ek = 2 × 3.7 × 10–19 – 3.7 × 10–19 = 3.7 × 10–19 J (1)
3
[13]
M6.
(a)
(i)
suitable variable input (variable power supply orvariable resistor) (1)
protective resistor and diode forward biased (1)
correct current and pd measuring devices (1)
3
(ii)
the mark scheme for this part of the question includes an
overall assessment for the Quality of Written Communication
QWC
descriptor
mark
range
goodexcellent
Uses accurately appropriate grammar, spelling,
punctuation and legibility.
Uses the most appropriate form and style of writing to give
an explanation or to present an argument in a well
structured piece of extended writing.
[May include bullet points and/or formulae or equations].
Answer refers to at least 5 of the relevant points listed
below.
5-6
modestadequate
Only a few errors.
Some structure to answer, style acceptable, arguments or
explanations partially supported by evidence or examples.
Answer refers to at least 3 or the relevant points listed
below.
3-4
Several significant errors.
Answer lacking structure, arguments not supported by
evidence and contains limited information.
Answer refers to no more than 2 of the relevant points.
1-2
poorlimited
incorrect,
inappropriate No answer at all or answer refers to unrelated, incorrect or
or no
inappropriate physics.
response
0
The explanation expected in a competent answer shouldinclude a coherent
selection of the following physics ideas.
connect circuit up (1)
measure current (I) and pd/voltage (V) (1)
vary resistance/voltage (1)
obtain a range of results (1)
reverse connections to power supply (and repeat) (1)
plot a graph (of pd against current) (1)
mention of significance of 0.6V or disconnect between readingsor change range on
meters when doing reverse bias (1)
(b)
(i)
(use of I = V/R)
I = 12/8 (1)= 1.5A (1)
(ii)
I = (12 – 0.65 (1))/4 = 2.8 A (1) sig figs (1)
5
[14]
M7.
(a) the mark scheme for this part of the question includes an overallassessment for the
Quality of Written Communication
QWC
descriptor
mark
range
good-excellent
Uses accurately appropriate grammar, spelling,
punctuation and legibility.Uses the most appropriate form
and style of writing to give an explanation or to present an
argument in a well structured piece of extended
writing.[May include formulae or equations].Answer refers
to at least 5 of the relevant points listed below.
5-6
modest-adequate
Only a few errors.Some structure to answer, style
acceptable, arguments or explanations partially supported
by evidence or examples.Answer refers to at least 3 or the
relevant points listed below.
3-4
poor-limited
Several significant errors.Answer lacking structure,
arguments not supported by evidence and contains limited
information.Answer refers to no more than 2 of the relevant
points.
1-2
incorrect,inappropriateor No answer at all or answer refers to unrelated, incorrect or
noresponse
inappropriate physics.
The explanation expected in a competent answer should include a
coherent selection of the following physics ideas.
electron in atoms can only occupy certain (discrete) energy levels (1)
the ground state is the lowest energy state an electron/atom can occupy (1)
electrons collide with (orbital) electrons (1)
giving the electrons the energy necessary to move to a higher level (1)
electrons later return to a lower level/ground state losing energy (1)
by emitting photons of a characteristic/different/discrete/certain/
varying frequencies or ΔE = hf or frequency depends on energy
difference (1)
0
(b)
(i)
the 5.5 eV electron does not have enough energy to excite
an (orbital) electron/atom (1)
the 9.0 eV electron provide enough energy to excite an (orbital)
electron/atom (1)
(ii)
energy = 9.0 × 1.6 × 10–19 (1) = 1.44 × 10–18 (J) (1)
(iii)
E = 1.44 × 10–18 – 1.6 × 10–19 = 1.28 × 10–18 (1) (J)
6.63 × 10–34 × f = 1.28 × 10–18 (1)
f = 1.28 × 10–18/6.63 × 10–34 = 1.9 × 1015 Hz (1)
7
[13]
M8.(a)
(use of R = ρl/A)
R = 4.0 × 10–3 × 0.060 (1)/(π × 0.0122) (1)
R = 0.53 (Ω) (1)
2 significant figures (1)
4
(b)
the mark scheme for this part of the question includes an overallassessment for the
Quality of Written Communication
circuit must include:
voltmeter and ammeter connected correctly (1)
power supply with means of varying current (1)
2
QWC
goodexcellent
descriptor
(i)
Uses accurately appropriate grammar, spelling,
punctuation and legibility.
(ii)
Uses the most appropriate form and style of
writing to give an explanation or to present an
argument in a well structured piece of extended
writing.[may include bullet points and/or formulae
or equations]
An excellent candidate will have a working circuit
diagram with correct description of measurements
mark
range
5-6
(including range of results) and processing. An
excellent candidate uses a range of results and finds a
mean value or uses a graphical method, eg IV characteristics. They also mention precision eg use
of vernier callipers.
(i)
modestadequate
poor-limited
Only a few errors.
(ii) Some structure to answer, style acceptable,
arguments or explanations partially supported by
evidence or examples.
An adequate candidate will have a working circuit and a
description with only a few errors, eg do not consider
precision. They have not taken a range of results and
fail to realise that the diameter needs to be measured in
several places.
(i)
Several significant errors.
(ii)
Answer lacking structure, arguments not
supported by evidence and contains limited
information.
3-4
1-2
Several significant errors, eg important measurement
missed, incorrect circuit, no awareness of how to
calculate resistivity.
incorrect,
inappropriate
or no
response
0
The explanation expected in a good answer should include a coherentaccount of the
procedure and include most of the following points.
•
length with a ruler
•
thickness/diameter with vernier callipers/micrometer
•
measure voltage
•
measure current
•
calculate resistance
•
use of graph, eg I-V or resistance against length
•
use of diameter to calculate cross-sectional area
•
mention of precision, eg vernier callipers or full scale readingsfor V and I
•
flat metal electrodes at each end to improve connection
6
[12]
M9.
(a)
(i)
working circuit including power supply and thermistor
(correct symbol) (1)
voltmeter and ammeter or ohm meter (1)
2
(ii)
The candidate’s writing should be legible and the spelling,punctuation and
grammar should be sufficiently accuratefor the meaning to be clear.
The candidate’s answer will be assessed holistically. The answerwill be assigned to
one of three levels according to the followingcriteria.
High Level (Good to excellent): 5 or 6 marks
The information conveyed by the answer is clearly organised,logical and coherent,
using appropriate specialist vocabularycorrectly. The form and style of writing is
appropriate toanswer the question.The candidate states that the thermistor is
connected in asuitable circuit with voltmeter and ammeter or ohmmeter.The
candidate gives details of how the thermistor is heatedin a beaker of water or a
water bath and a thermometer is usedto measure the temperature at small regular
intervals.The candidate states that the resistance is found at varioustemperatures
either directly with an ohmmeter or by dividingvoltage by current. The candidate
may mention that the watermust be stirred to ensure that the thermistor is at
thetemperature measured by the thermometer.The candidate may give some
indication of the range oftemperatures to be used.The candidate may refer to
repetition of whole experiment.The candidate may plot a graph of resistance against
temperature.The candidate may use a digital thermometer.
Intermediate Level (Modest to adequate): 3 or 4 marks
The information conveyed by the answer may be less well
organised and not fully coherent. There is less use of specialist
vocabulary, or specialist vocabulary may be used incorrectly.
The form and style of writing is less appropriate.
The candidate states that the thermistor is connected in a
suitable circuit with voltmeter and ammeter or ohmmeter.
The candidate gives details of how the thermistor is heated
in a beaker of water and a thermometer is used to measure
the temperature.
The candidate states that the resistance is found at various
temperatures either directly with an ohmmeter or by dividing
voltage by current.
Low Level (Poor to limited): 1 or 2 marks
The information conveyed by the answer is poorly organisedand may not be
relevant or coherent. There is little correctuse of specialist vocabulary.The form and
style of writing may be only partly appropriate.
The candidate changes temperature at least once andmeasures V and I or R.
The explanation expected in a competent answershould include a coherent
selection of the followingpoints concerning the physical principles involved
andtheir consequences in this case.
Max 6
(b)
(i)
pd = 6.0 – 1.6 = 4.4 (V) (1)
1
(ii)
current = 4.4/1200 = 3.7 × 10–3 (A) (1) (not 3.6)
1
(iii)
resistance = 1.6/3.7 × 10–3 = 440 or 430 (Ω) (1)
2 sfs (1)
2
(c)
less current now flows or terminal pd/voltage lower (1)
(or voltage across cell/external circuit is lower)
(hence) pd/voltage across resistor will decrease (1)
2
[14]
M10.
(a) The candidate’s writing should be legible and the spelling,
punctuation and grammar should be sufficiently accurate
for the meaning to be clear.
The candidate’s answer will be assessed holistically. The
answer will be assigned to one of three levels according to the
following criteria.
High Level (Good to excellent): 5 or 6 marks
The information conveyed by the answer is clearly organised,logical and coherent, using
appropriate specialist vocabularycorrectly. The form and style of writing is appropriate to
answerthe question.
The candidate provides a comprehensive and coherentdescription which includes a clear
explanation of constantenergy level differences and how electrons can be excitedby
electron collisions. The link between the energy of a photonand its frequency should be
clear. The description shouldinclude a clear explanation of the reason atoms of a
givenelement emit photons of a characteristic frequency or thereis a clear link between
constant energy differences and photonfrequency/wavelength (eg E=hf).The candidate
should relate the energy difference betweenlevels to the energy of emitted photons and
state the energydifference is fixed/constant.
Intermediate Level (Modest to adequate): 3 or 4 marks
The information conveyed by the answer may be less well
organised and not fully coherent. There is less use of specialist
vocabulary, or specialist vocabulary may be used incorrectly.
The form and style of writing is less appropriate.
The candidate provides an explanation of energy levels and
how excitation takes place by electron collision with
atomic/orbital electrons. The candidate explains how an
orbital/atomic electron loses energy by emitting a photon.
Low Level (Poor to limited): 1 or 2 marks
The information conveyed by the answer is poorly organised
and may not be relevant or coherent. There is little correct
use of specialist vocabulary.
The form and style of writing may be only partly appropriate.
Some mention of energy levels and the idea of excitation of
electron. Talk about excitation of atom instead of electron limits
the mark to 1.
Incorrect, inappropriate of no response: 0 marks
No answer or answer refers to unrelated, incorrect or inappropriate physics.
The explanation expected in a competent answer should include acoherent account
of the significance of discrete energy levelsand how the bombardment of atoms by
electrons can lead toexcitation and the subsequent emission of photons of a
characteristicfrequency.
electrons bombard atoms of vapour and give energy to electrons in atom
electrons move to a higher energy level
electrons are excited
excited electrons move down to lower energy levels losing energy byemitting photons
photons have energy hf
photons of characteristic frequencies emitted from atoms of aparticular element
this is because atoms have discrete energy levels which areassociated with particular
energy values
max 6
(b)
(i)
energy required to (completely) remove an electron
from atom/hydrogen
ground state/lowest energy level
2
(ii)
13.6 × 1.6 × 10–19
= 2.18 × 10–18 (J)
3 sfs
3
[11]
M11.
(a)
(i)
circuit with ammeter and voltmeter correct or ohmmeter
some means of heating eg water bath
thermometer in water bath
3
(ii)
The candidate’s writing should be legible and the spelling, punctuation
and grammar should be sufficiently accurate for the meaning to be clear.
The candidate’s answer will be assessed holistically. The answer will be assigned
to one of three levels according to the following criteria.
High Level (Good to excellent): 5 or 6 marks
The information conveyed by the answer is clearly organised, logical and coherent,
using appropriate specialist vocabulary correctly. The form and style of writing is
appropriate to answer the question.
The candidate states that resistance is measured using an ohmmeter or voltmeter
ammeter method. The wire is heated in a beaker of water and the temperature
measured with a thermometer. Ice is added to the water and the water is stirred as
the water is heated. Details of how resistance is calculated and how results are
presented e.g. graph of resistivity against temperature.
Intermediate Level (Modest to adequate): 3 or 4 marks
The information conveyed by the answer may be less well organised and not fully
coherent. There is less use of specialist vocabulary, or specialist vocabulary may be
used incorrectly. The form and style of writing is less appropriate.
The candidate states that resistance is measured using an ohmmeter or voltmeter
ammeter method. The wire is heated in a beaker of water and the temperature
measured with a thermometer. Ice is added to the water. Details of how resistance
is calculated.
Low Level (Poor to limited): 1 or 2 marks
The information conveyed by the answer is poorly organised and may not be
relevant or coherent. There is little correct use of specialist vocabulary. The form
and style of writing may be only partly appropriate.
The candidate states that resistance is measured using an ohmmeter or voltmeter
ammeter method. The wire is heated in a beaker of water and the temperature
measured with a thermometer.
The explanation expected in a competent answer should include a coherent
selection of the following points concerning the physical principles involved
and their consequences in this case.
•
resistance measured calculated
•
water bath used
•
ice added to water
•
water stirred
•
temperature measured with thermometer
•
resistance calculated
•
graph drawn
6
(b)
the temperature at or below which a material
becomes a superconductor or has zero resistance/resistivity
2
[11]
M12.
(a) The candidate’s writing should be legible and the spelling, punctuation and
grammar should be sufficiently accurate for the meaning to be clear.
The candidate’s answer will be assessed holistically. The answer will be assigned to one
of three levels according to the following criteria.
High Level (Good to excellent): 5 or 6 marks
The information conveyed by the answer is clearly organised, logical and coherent, using
appropriate specialist vocabulary correctly. The form and style of writing is appropriate to
answer the question.
The candidate states that the power supply is connected to the input of the oscilloscope.
The time base is switched off and the y gain adjusted until a complete vertical line is seen
on the screen. The length of the line is measured and this is converted to peak to peak
voltage using the calibration. The peak voltage is divided by root two to get the rms
voltage and this is compared with the stated value. The time base is now switched on and
adjusted until a minimum of one cycle is seen on the screen. The length of one cycle is
measured and this is converted to time using the time base setting. Frequency is the
reciprocal of this time.
Intermediate Level (Modest to adequate): 3 or 4 marks
The information conveyed by the answer may be less well organised and not fully
coherent. There is less use of specialist vocabulary, or specialist vocabulary may be used
incorrectly. The form and style of writing is less appropriate.
The candidate states that the power supply is connected to the input of the oscilloscope.
The y gain adjusted. The length of the line/height of peak is measured. The peak voltage
is divided by root two to get the rms voltage. The time base is now switched on and
adjusted until a minimum of one cycle is seen on the screen. The length of one cycle is
measured and this is converted to time using the time base setting.
Low Level (Poor to limited): 1 or 2 marks
The information conveyed by the answer is poorly organised and may not be relevant or
coherent. There is little correct use of specialist vocabulary. The form and style of writing
may be only partly appropriate.
The candidate states that the power supply is connected to the input of the oscilloscope.
The length of the line/height of peak is measured. The time base is now switched on and
adjusted until a minimum of one cycle is seen on the screen. The length of one cycle is
measured and this is converted to time.
The explanation expected in a competent answer should include a coherent
selection of the following points concerning the physical principles involved and
their consequences in this case.
•
power supply connected to oscilloscope input
•
time base initially switched off
•
y gain adjusted to get as long a line as possible
•
length of line used to find peak to peak voltage
•
rms voltage found
•
time base switched on and adjusted to get several cycles on the screen
•
use the time base setting to find period
•
use period to find frequency
•
compare vales with stated values
6
(b)
(i)
(use of P = IV)
I = 24/12 = 2.0 (A)
1
(ii)
peak current = √2 × 2.0 = 2.8 (A)
1
(iii)
peak power = √2 × 12 × √2 × 2.0
= 48 (W)
2
[10]
M13.(a)
a component with constant resistance OR V ∝ I
1
(b)
(i)
circuit using correct symbols with means of varying current / voltage
correct voltmeter and ammeter
ignore symbol for component
unless it is a variable resistor
2
(ii)
The candidate’s writing should be legible and the spelling, punctuation and
grammar should be sufficiently accurate for the meaning to be clear.The
candidate’s answer will be assessed holistically. The answer will be assigned to one
of three levels according to the following criteria.
High Level (Good to excellent): 5 or 6 marksThe information conveyed by the
answer is clearly organised, logical and coherent, using appropriate specialist
vocabulary correctly. The form and style of writing is appropriate to answer the
question.
Candidate draws an appropriate circuit diagram with correctly positioned ammeter
and voltmeters. Candidate has a means of varying the current. Sets current to
different values and measures pd. Mentions wide range. Has a sensible way of
varying current (e.g. variable resistor / potential divider). Plots a graph of pd against
current. Relates constant gradient to a constant resistance.
Level 5 / 6meaning of line through originreverse current
readingssuitable range with suggested values
Intermediate Level (Modest to adequate): 3 or 4 marksThe information conveyed
by the answer may be less well organised and not fully coherent. There is less use
of specialist vocabulary, or specialist vocabulary may be used incorrectly. The form
and style of writing is less appropriate.Candidate draws an appropriate circuit
diagram with correctly positioned ammeter and voltmeters. Candidate has a means
of varying the current. Varies current and measures pd. Plots a graph of pd against
current. Relates constant gradient to a constant resistance.
Level 3 / 4Draw best fit line or state R constantRelate straight line
on graph to ohmic conductor
Low Level (Poor to limited): 1 or 2 marksThe information conveyed by the answer
is poorly organised and may not be relevant or coherent. There is little correct use of
specialist vocabulary. The form and style of writing may be only partly appropriate.
The candidate measures resistance at least twice to see if constant. Has some
means of varying current.
Level 1 / 2Take several readings of V and I and plot graph or
calculate R
The explanation expected in a competent answer should include a coherent
selection of the following points concerning the physical principles involved
and their consequences in this case.
method for varying currentcurrent varied in regular stepspd and current
measureresistance calculatedgraph drawnsignificance of gradient of the graph
discussed
6
(c)
(i)
a material with zero resistivity / resistance
not negligible
1
(ii)
material becomes superconducting at / below critical temperature
accept reverse argument
1
(iii)
any correct usage e.g. powerful magnets, mri, maglev trains / bullet train / (high
power) transmission lines / particle accelerators / LHC
1
[12]
M14.(a)
The candidate’s writing should be legible and the spelling, punctuation and grammar
should be sufficiently accurate for the meaning to be clear.The candidate’s answer
will be assessed holistically. The answer will be assigned to one of three levels according
to the following criteria.
High Level (Good to excellent): 5 or 6 marksThe information conveyed by the answer is
clearly organised, logical and coherent, using appropriate specialist vocabulary correctly.
The form and style of writing is appropriate to answer the question.
Top Band
Both have rest massMention electromagnetic interaction Correct
quark structure of mesons and baryonsBoth hadrons and leptons
interact/decay through weak interactionFor 6 marks must have
last two points
Candidate gives correct examples of hadrons and leptons. Identifies the differences
between hadrons and leptons (hadrons affected by strong nuclear reaction and are made
of quarks). Leptons are fundamental and do not experience the strong nuclear reaction.
Hadrons are divided into baryons and mesons. Baryons three quarks, mesons quark antiquark pair. Similarities between groups all experience weak interaction and if charged the
electromagnetic interaction. All have rest mass.
Intermediate Level (Modest to adequate): 3 or 4 marksThe information conveyed by
the answer may be less well organised and not fully coherent. There is less use of
specialist vocabulary, or specialist vocabulary may be used incorrectly. The form and style
of writing is less appropriate.
Middle band
Only hadrons experience strong nuclear interaction (need this to
get in middle band)Hadrons are mesons or baryons. Examples of
each
Candidate gives correct examples of hadrons and leptons. Identifies one difference
between hadrons and leptons (e.g. hadrons affected by strong nuclear reaction or are
made of quarks). Leptons are fundamental. Hadrons are divided into baryons and
mesons.
Low Level (Poor to limited): 1 or 2 marksThe information conveyed by the answer is
poorly organised and may not be relevant or coherent. There is little correct use of
specialist vocabulary. The form and style of writing may be only partly appropriate.
Lower band
1 or 2 correct facts about hadrons leptons eg Leptons are
fundamental / hadrons made of quarks
Identifies two correct properties of hadrons and leptons.
The explanation expected in a competent answer should include a coherent
selection of the following points concerning the physical principles involved and
their consequences in this case.example of hadron and leptonmention of strong
interactionmention of quark structure hadronsleptons are fundamentalidentify baryons and
mesonsgives quark structure of baryons and mesonssimilarities e.g. all have rest massall
affected by weak interactionif charged both experience electromagnetic interaction
6
(b)
(i)
a correct example of particle e.g. electronand correct example of antiparticle e.g.
positron
Allow correct symbolsAllow antielectron for positronAlso allow pi
zero and gamma
1
(ii)
correct difference e.g. opposite charge/other named quantum number
must be consistent with (i)
1
[8]
M15.
(a)
same wavelength or frequency (1)
same phase or constant phase difference (1)
2
(b)
The marking scheme for this part of the question includes an overallassessment for the
Quality of Written Communication (QWC).There are no discrete marks for the assessment
of QWC but thecandidates’ QWC in this answer will be one of the criteria usedto assign a
level and award the marks for this part of the question.
Level
Descriptor
an answer will be expected to meet most of the criteria in the
level descriptor
Good 3
Mark
range
– answer includes a good attempt at the explanations
required
– answer makes good use of physics ideas including
knowledge beyond that given in the question
– explanation well structured with minimal repetition or
irrelevant points and uses appropriate scientific language
– accurate and logical expression of ideas with only
minor/occasional errors of grammar, punctuation and
spelling
5-6
Modest 2
– answer includes some attempts at the explanations
required
– answer makes use of physics ideas referred to in the
question but is limited to these
3-4
– explanation has some structure but may not be complete
– explanation has reasonable clarity but has a few errors of
grammar and/or punctuation and spelling
Limited 1
– answer includes some valid ideas but these are not
organised in a logical or clear explanation
– answer lacks structure
1-2
– several errors in grammar, punctuation and spelling
0
– incorrect, inappropriate or no response
0
the explanations expected in a competent answer should include a coherent selection of
the following physics ideas:
(c)
•
narrow single slit gives wide diffraction
•
to ensure that both S1 and S2 are illuminated
•
slit S acts as a point source
•
narrow single slit ensures it provides coherent sources of light atS1 and S2
•
S1 and S2 are illuminated by same source giving same wavelength
•
paths to S1 and S2 are of constant length giving constant phasedifference or SS1 and
SS2 so waves are in phase
•
light is diffracted as it passes through S1 and S2 and the diffractedwaves overlap and
interfere
•
where the path lengths from S1 and S2 to the screen differ bywhole numbers, n of
wavelengths, constructive interferenceoccurs producing a bright fringe on the
screen
•
where the path lengths differ by (n + ½) wavelengths, destructiveinterference occurs
producing a dark fringe on the screen
graph to show: maxima of similar intensity to central maximum (1)
(or some decrease in intensity outwards from centre)
all fringes same width as central fringe (1)
2
[10]
M16.
(a) the force (needed to stretch a spring is directly) is proportional
to the extension (of the spring from its natural length) or equation
with all terms defined (1)
up to the limit of proportionally (1)
2
(b)
(i)
The explanations expected in a competent answer shouldinclude a coherent
account of the following measurementsand their use
measurements
(use a metre rule to) measure the length of the spring (1)
when it supports a standard mass (or known) mass (m) andwhen it supports the
rock sample
repeat for different (standard) masses
accuracy – use a set square or other suitable method tomeasure the position of the
lower end of the spring againstthe (vertical) mm rule or method to reduce parallax
use of measurements
either
plot graph of mass against length (or extension) (1)
read off mass corresponding to length (or extension) due
to the sample (1)
or
the extension of the spring = length – unstretched length (1)
(ii)
use a (G) clamp (or suitable heavy weight) to fix/clamp the
base of the stand to the table (1)
clamp (or weight) provides an anticlockwise moment (about
the edge of the stand greater than the moment of the object
on the spring)/ counterbalances (the load) (1)
or adjust the stand so the spring is nearer to it (1)
so the moment of the load is reduced (and is less likely to
overcome the anticlockwise moment of the base of the stand
about the edge of the stand) (1)
or turn the base of the stand/rotate the boss by 180° (1)
so the weight of the load acts through the base (1)
2
[10]
M17.
(a)
(i)
the lines are not straight (owtte) (1)
(ii)
there is no permanent extension (1)(or the overall/final extension is zero or the
unloading curvereturns to zero extension)
(iii)
(area represents) work done (on or energy transfer to therubber cord)
or energy (stored) (1) not heat/thermal energy
3
(b)
the mark scheme for this part of the question includes an overall
assessment for the Quality of Written Communication
QWC
descriptor
mark
range
goodexcellent
The candidate provides a comprehensive and coherent
description which includes nearly all the necessary
procedures and measurements in a logical order. The
descriptions should show awareness of how to apply a
variable force. They should know that measurements are
to be made as the force is increased then as it is
decreased. In addition, they should know how to
calculate/measure the extension of the cord. At least five
different masses/’large number’ of masses are used.
Minimum 7 masses to reach 6 marks. The diagram
should be detailed.
5-6
modestadequate
The description should include most of the necessary
procedures including how to apply a variable force and
should include the necessary measurements. They may
not have described the procedures in a logical order. They
may not appreciate that measurements are also to be
made as the cord is unloaded. They should know that the
extensionof the cord must be found and name a suitable
measuring instrument (or seen in diagram – label need
not be seen)/how to calculate. The diagram may lack
some detail.
3-4
poorlimited
The candidate knows that the extension or cord length is
to be measured for different forces – may be apparent
from the diagram. They may not appreciate that
measurements are also to be made as the cord is
unloaded.
They may not state how to calculate the extension of the
1-2
cord. The diagram may not have been drawn.
incorrect,
inappropriate No answer at all or answer refers to unrelated, incorrect or
or no
inappropriate physics.
response
0
The explanation expected in a competent answer should includea coherent
selection of the following physics ideas.
diagram showing rubber cord fixed at one end supporting a weightat the other end or
pulled by a force (1)
means of applying variable force drawn or described (eg use of standardmasses or a
newtonmeter) (1)
means of measuring cord drawn or described (1)
procedure
measured force applied ( or known weights used) (1)
cord extension measured or calculated (1)
repeat for increasing then decreasing length (or force/weight) (1)
extension calculated from cord length – initial length (1)
[9]
M18.
(a)
(i)
(u = 0, s = 0.16 m, a = 9.8(1) m s–2)
(rearranging s = ut + ½ at2 with u = 0 gives)
t2 =
or v2 = u2 + 2gs or 0.16 = 1/2 × 9.81 t2
or t0 =
(1) = 0.1804 or 0.1806 or 0.181 etc (1)
(s) 2 sf only (1)
(ii)
(v0 = u + at0 =) 0 + 9.81 × 0.18 ecf (a) (i) or v2 = 2 × 9.81 × 0.16 (1)
= 1.8 or 1.77 (m s–1) (1)
5
(b)
the mark scheme for this part of the question includes an overallassessment for the
Quality of Written Communication
QWC
descriptor
mark
range
good-excellent
The candidate provides a correct description of the motion
of the ball including its deceleration in the fluid
decreasingand becoming zero (or attaining constant
velocity). They should give a comprehensive and coherent
explanation which includes nearly all the necessary
principles in a logical order. In their explanation, the
candidate should refer to the forces including
their directions acting on the ball, why theresistive force
decreases and why the acceleration becomes zero.
5-6
modest-adequate
The description should refer to the ball decelerating in the
fluid until it becomes zero or attains constant velocity.
Their explanation should be fairly coherent although it may
not be comprehensive and may focus only on the forces
acting when the ball attains constant velocity - balanced
forces - or on the reason for the initial deceleration.
3-4
poor-limited
The candidate knows that the
ball decelerates (acceleration with direction) or is acted on
by an upward force (as well as the force of gravity). Their
explanation of why the ball attains constant velocity may
be absent.
1-2
May be sketchy and lacks key considerations. They may
not appreciate that the two forces are equal and opposite
when the ball is moving at constant velocity.
incorrect,inappropriateor No answer at all or answer refers to unrelated, incorrect or
noresponse
inappropriate physics.
0
The explanation expected in a competent answer should include acoherent
selection of the following physics ideas.
The ball decelerates/slows down in the fluid (1) if acceleration is usedthe direction must
be specified
•
because a force due to fluid friction/resistance/viscosity acts(upwards) on the ball (1)
•
(and) the force due to the fluid is greater than the weightof the ball (1)
•
resistive force is upwards (1)
•
resistive force decreases (1)
The deceleration decreases (to zero) (1)
•
because the force due to fluid friction/resistance/viscositydecreases as the ball’s
speed decreases (1)
•
until it is equal (and opposite) to the weight of the ball (1)(or the resultant force is
zero)
•
gradient of graph gives the acceleration and the ball movesat constant/terminal
velocity/a = 0 (1)
[11]
M19.
(a) the mark scheme for this part of the question includes an overallassessment for the
Quality of Written Communication
QWC
goodexcellent
descriptor
(i)
Uses accurately appropriate grammar, spelling,
punctuation and legibility.
(ii)
Uses the most appropriate form and style of
writing to give an explanation or to present an
argument in a well structured piece of extended
writing.[may include bullet points and/or formulae
or equations]
Physics: describes a workable account of making most
measurements accurately.
mark
range
5-6
For 6 marks: complete description of the
measurements required + how to find the extension +
instruments needed + at least 2 accuracy points
For 5 marks: all 4 quantities measured
including varyingload + 2 instruments, 2 accuracy
points.
(i)
Only a few errors.
(ii) Some structure to answer, style acceptable,
arguments or explanations partially supported by
evidence or examples.
modestadequate
Physics: describes a workable account of making all or
most of the measurements and has some correct
awareness of at least one accurate measurement.
3-4
For 4 marks: all 4 quantities measured
including varyingload + 2 instruments mentioned + 1
accuracy point.
For 3 marks: 3 quantities
(load, extension, diameter orcross-sectional area)
may only omit original length + 1 instrument + 1
accuracy point.
poor-limited
(i)
Several significant errors.
(ii)
Answer lacking structure, arguments not
1-2
supported by evidence and contains limited
information.
Physics: unable to give a workable account but can
describe some of the measurements.
For 2 marks: load or mass + measure extension + one
instrument mentioned.
For 1 mark: applying a single load/mass + one other
quantity or one instrument named or shown.
incorrect,
inappropriate
or no
response
0
Quantities to be measured
•
describe/show means of applying a load/force to a wire
•
measure original length
•
measure extension
•
measure diameter
•
extension = extension length ‘ original length (needed for six marks)
Measuring instruments
•
use of rule/ruler/tape measure
•
measure diameter with micrometer
•
use of travelling microscope to measure extension, or extension
of wire measured with vernier scale for Searle’s apparatus
Accuracy
•
varying load/mass
•
repeat readings (of length or extension)
•
diameter measured in several places
•
Searle’s ‘control’ wire negating effect of temperature change
•
change in diameter monitored (with micrometer)
•
original length of wire ≥ 1.0 m
Additional creditworthy point
•
explain how cross-sectional area is found using A = π (D/2)2
•
showing how Young modulus is found is regarded as neutral
6
(b)
(i)
good straight line through origin (within one square) up
to stress = 5.1 × 107 and line that lies close to data points
thereafter (1)
1
(ii)
evidence of use of gradient or stress/strain (1)
Δ strain used ≥ 3.2 (× 10–3) for correct gradient calculation (1)
1.0 ± 0.05 × 1010 (1) (0.95 to 1.05) allow 1 sf
ecf form their line – may gain full marks
Pa or N m–2 or N/m2 only (1)
4
(c)
originates at last point + parallel to their first line + straight + touchesx axis (1)
1
[12]
M20.
(a)
(ΔEp = mgΔh) = 55 × 9.8(1) × 4.2 (1)
= 2300 (J) (1) (2266.1)
2
(b)
(i)
(Ek = 3.2/4.2 × 2264 or uses suitable kinematics equation)
= 1700(J) (1) (= 1724.8 = 1720)
1
ecf (a)
(ii)
(Ek = + mv2 = 1724.8) v =
ecf (b) (i)
= √62.72
or use of v2 = 2as (1)
= 7.9 m s–1 (1) (= 7.9196)
2
(c)
one arrow, vertical, upward pointing, starts on soles of feet (1)
1
(d)
(use of α =
gives) =
(1)
or ecf (b) (ii)/0.26
= 30 (m s–2) (1) (30.46)
or use α =
of or α =
(1)
allow incorrect values of s here
= 29.6 or 31.4 respectively (1)
2
(e)
The candidate’s writing should be legible and the spelling,
punctuation and grammar should be sufficiently accurate for the
meaning to be clear.
The candidate’s answer will be assessed holistically. The answer
will be assigned to one of three levels according to the following criteria.
High Level (Good to excellent): 5 or 6 marks
The information conveyed by the answer is clearly organised,
logical and coherent, using appropriate specialist vocabulary
correctly. The form and style of writing is appropriate to answer
the question.
Candidate must state that:
•
(elastic potential) energy is transformed to kinetic or
trampoline does work (on gymnast)
•
(KE) is transformed into (gravitational) potential energy
•
(the gymnast) must ‘jump’/bend knees/do work/‘use’
chemical energy/supply energy (to increase height)
For 6 marks, must also state that (the gymnast) must overcome
resistive forces (drag/heat loss/reference to energy ‘lost’ in
trampoline, etc)
Intermediate Level (Modest to adequate): 3 or 4 marks
The information conveyed by the answer may be less wellorganised and not fully
coherent. There is less use of specialistvocabulary, or specialist vocabulary may be used
incorrectly.The form and style of writing is less appropriate.
Candidate must state one from:
•
chemical energy (transferred) to elastic, kinetic orgravitational energy
•
PE (from trampoline) to KE (of gymnast)
•
KE (gymnast) to (G)PE (gymnast)
and one of the following:
•
work is done by the trampoline (on the gymnast)
•
that work is done on the trampoline (by the gymnast)
•
work done against resistive forces
•
(additional) energy input required (to achieve additionalheight)
Low Level (Poor to limited): 1 or 2 marks
The information conveyed by the answer is poorly organisedand may not be relevant or
coherent. There is little correct useof specialist vocabulary. The form and style of writing
may beonly partly appropriate.
Candidate must
•
give one relevant energy gain or loss in the system orstate that energy is input to
reach greater height
For two marks, a relevant energy transformation must begiven or one further marking
point:
•
(to reach the same height) the gymnast must do workin order to replace the energy
wasted as the springsand the trampoline (rubber) unload (contract)
•
to reach a greater height, the gymnast must do additionalwork by (bending and)
extending her legs (jumping) asthe trampoline moves upwards
•
the additional downward force keeps the trampolineextended for longer, thus
increasing the impulse
•
correct reference to law of energy conservation
max 6
[14]
M21.
The candidate’s writing should be legible and the spelling, punctuation
and grammar should be sufficiently accurate for the meaning to be clear.
The candidate’s answer will be assessed holistically. The answer will be
assigned to one of the three levels according to the following criteria.
High Level (good to excellent) 5 or 6 marks
The information conveyed by the answer is clearly organised, logical and
coherent, using appropriate specialist vocabulary correctly. The form and
style of writing is appropriate to answer the question.
Mentions waves travelling in opposite directions or waves of same
frequency (and amplitude) and superpose or interfere or add together.
Intermediate Level (modest to adequate) 3 or 4 marks
The information conveyed by the answer may be less well organised andnot fully coherent.
There is less use of specialist vocabulary, or specialistvocabulary may be used incorrectly. The
form and style of writing is lessappropriate.
Mentions waves travelling in opposite directions (accept ‘waves reflect/rebound back or from
clamp’) or superposition/addition/interference ofwaves or waves of same
frequency/wavelength.
Low Level (poor to limited) 1 or 2 marks
The information conveyed by the answer is poorly organised and may not
be relevant or coherent. There is little correct use of specialist vocabulary.
The form and style of writing may only be partly appropriate.
One correct key feature or one relevant remark regarding formation given.
The explanation expected in a competent answer should include a
coherent account of the following points concerning the physical
principles involved and their consequences in this case.
•
4 nodes where there is no movement/zero amplitude
•
3 antinodes where amplitude is maximum
•
wavelength 0.80 m
•
end antinodes in phase/middle and ends in antiphase
•
between node and antinode, amplitude of oscillation increases
•
waves reflect off the clamp (and the rod)
•
waves travelling in opposite directions superpose/add/interfere
•
wave have same wavelength and frequency (similar amplitude)
•
always cancellation at nodes/always constructive superposition at antinodes
•
energy is not transferred along string
[6]
M22.
(a) The candidate’s writing should be legible and the spelling, punctuation and
grammar should be sufficiently accurate for the meaning to be clear.
The candidate’s answer will be assessed holistically. The answer will be assigned to one
of three levels according to the following criteria.
High Level (Good to excellent): 5 or 6 marks
The information conveyed by the answer is clearly organised, logical and coherent, using
appropriate specialist vocabulary correctly. The form and style of writing is appropriate to
answer the question.
The candidate provides a comprehensive and coherent description which includes; fringe
spacing/separation w and distance D
measured with one instrument named, uses λ =
to obtain value for λ,
measures distance between several maxima and includes a valid point about safety.
Intermediate Level (Modest to adequate): 3 or 4 marks
The information conveyed by the answer may be less well organised
and not fully coherent. There is less use of specialist vocabulary, or specialist vocabulary
may be used incorrectly. The form and style of writing is less appropriate.
The candidate provides an adequate explanation that lacks some of the essential points.
The candidate is expected to include; w or ‘fringes’ measured or uses
λ=
to obtain value for λ. They include one accuracy point or a valid point about
safety.
Low Level (Poor to limited): 1 or 2 marks
The information conveyed by the answer is poorly organised and may not be relevant or
coherent. There is little correct use of specialist vocabulary. The form and style of writing
may be only partly appropriate.
The candidate provides a limited explanation with no more than one or two valid points.
Incorrect, inappropriate of no response: 0 marks
No answer or answer refers to unrelated, incorrect or inappropriate physics.
The explanation expected in a competent answer should include a coherent
selection of the following points.
Measurements
•
suitable measuring instrument for w
•
suitable measuring instrument for D
Finding the wavelength
•
•
uses λ =
to obtain value for λ.
explains graphical approach
Accuracy
•
several fringe spaces measured
•
centres of fringes used
•
five or more fringes/four fringe spaces measured
•
large value of D
•
D greater than or equal to 2 m
•
dark room
•
repeat measurements
•
vernier calliper for w (not ‘calliper’, not micrometer)
•
graphical method varying D and measuring w
•
other valid accuracy point
Safety
•
avoid shining laser at (or near) a person
•
laser safety goggles
•
avoid reflections
•
warning sign or light
Max 6
(b)
(light from both sources has) constant phase relationship / difference
‘in phase’ or ’same wavelength’ or ‘same frequency’ is one mark
2
(c)
single slit then double slits to the right
single slit and double slits labelled
2
(d)
if candidate refers to white light
Young’s fringes with white light;
orif candidate refers to the laser;
contain (different)
colours or central white fringe
monochromatic/one colour
less intense
more intense
maxima wider/minima
maxima narrower/minima
narrower ormax or min closer
together for white light compared
to a red laser
wider ormax or min further apart
for a redlaser
fringes/lines/bands etc compared
to ‘dots’
‘dots’ for laser compared to
‘bands’ etc
2
from each row, one only max 2
(e)
cancellation / waves cancel / destructive interference/
destructive superposition
(light from one slit meets light from the other) in antiphase (180 out of phase)
or a path difference of ((n+) ½) λ
2
[14]
M23.
(a)
max three from
central maximum shown
two equally spaced first order maxima
central and one first order labelled correctly
central white maximum
indication of spectra/colours in at least one first order beam
at least one first order beam labelled with violet (indigo or blue) closest to the
centre or red furthest
3
(b)
dark/black lines or absorption spectrum or Fraunhofer lines
(reveal the) composition (of the star’s atmosphere)
accept dark ‘bands’
accept atoms or elements in the star
or the peak of intensity
(is related to) the temperature
or Doppler (blue or red) shift
(speed of) rotation or speed of star (relative to Earth)
2
(c)
(i)
grating and screen shown with both labelled
laser or laser beam labelled
2
(ii)
The candidate’s writing should be legible and the spelling, punctuation
and grammar should be sufficiently accurate for the meaning to be clear.
The candidate’s answer will be assessed holistically. The answer will be
assigned to one of three levels according to the following criteria.
High Level (Good to excellent): 5 or 6 marks
The information conveyed by the answer is clearly organised, logical and
coherent, using appropriate specialist vocabulary correctly. The form and style
of writing is appropriate to answer the question.
•
correct use of (n)λ = d sin θ
•
and measure appropriate angle (eg ‘to first order beam’ is the minimum
required)
•
and method to measure angle (eg tan θ = x/D, spectrometer, accept
protractor)
•
and at least one way of improving accuracy/reliability
•
for full marks: also explain how d is calculated, eg d = 1/ lines per mm
(× 103)
Intermediate Level (Modest to adequate): 3 or 4 marks
The information conveyed by the answer may be less well organised and notfully
coherent. There is less use of specialist vocabulary, or specialistvocabulary may be
used incorrectly. The form and style of writing is lessappropriate.
•
use of (n)λ = d sin θ
•
and measure appropriate angle (eg ‘to first order beam’ is the minimum
required)
•
and method of measurement of θ (eg tan θ = x/D, spectrometer, accept
protractor) or at least one way of improving accuracy/reliability
Low Level (Poor to limited): 1 or 2 marks
The information conveyed by the answer is poorly organised and may not be
relevant or coherent. There is little correct use of specialist vocabulary. The form
and style of writing may be only partly appropriate.
•
use of (n)λ = d sin θ
•
or measure appropriate angle (eg ‘to first order beam’ is the minimum
required)
•
or at least one way of improving accuracy/reliability
Incorrect, inappropriate of no response: 0 marks
No answer or answer refers to unrelated, incorrect or inappropriate physics.
The explanation expected in a competent answer should include
Accuracy/reliability points
•
measure between more than one order (eg 2 θ)
•
measure θ for different orders (for average λ not average angle)
•
check or repeat/repeat for different distances (D)
•
use of spectrometer
•
use large distance to screen (D)
•
protractor with 0.5 degree (or less) intervals
•
graphical method: plot sin θ against n (gradient = λ/d)
6
[13]
M24.Good / Excellent
The candidate’s writing should be legible and the spelling, punctuation and
grammar should be sufficiently accurate for the meaning to be clear.The candidate’s
answer will be assessed holistically. The answer will be assigned to one of three levels
according to the following criteria.
High Level (Good to excellent): 5 or 6 marksThe information conveyed by the answer is
clearly organised, logical and coherent, using appropriate specialist vocabulary correctly. The
form and style of writing is appropriate to answer the question.
can say disturbance, amplitude or displacement
Mentions:
•
(1) waves (meet when) travelling in opposite directions / cross/ wave meets a
reflected wave / etc
•
(2) same wavelength (or frequency)
•
(3) node – point of minimum or no disturbance
•
(4) antinode – point of maximum disturbance / maximum displacement/amplitude
occurs
•
(5) node - two waves (always) cancel / destructive interference / 180o phase
difference (between displacements of the two waves at the node)
•
(6) antinode – reinforcement / constructive interference occurs / (displacements) in
phase
•
(7) mention of superposition of the two waves
5 marks: points (1) AND (2) with three points from (3), (4), (5), (6) or (7)
for 6 marks: points (1) to (6) must be seen
labelled diagram can provide supporting evidence but labels:
‘node’ / ‘antinode’ by themselves cannot replace points 3 and 4
5/6
Modest
Intermediate Level (Modest to adequate): 3 or 4 marks
The information conveyed by the answer may be less well organised and not fully coherent.
There is less use of specialist vocabulary, or specialist vocabulary may be used incorrectly. The
form and style of writing is less appropriate.
Mentions any 3 of the 7 points.
4 marks: (1) OR (2) AND three others.
3/4
LimitedLow Level (Poor to limited): 1 or 2 marksThe information conveyed by the answer is
poorly organised and may not be relevant or coherent. There is little correct use of specialist
vocabulary. The form and style of writing may be only partly appropriate.
One relevant point
OR a relevant, labelled diagram
2 marks: two points OR one point and a relevant labelled diagram
1/2
[6]
M25.(a)
vol =
π0.0113 = (5.5753) 5.6 × 10−6 ( m3 )
(m = ρV )
(= 8100 × 5.575 × 10−6 =) 0.045 (kg)
ecf from first part
Allow use of g = 10
0.36 kg , 3.5 N from use of diameter rather than radius (max 3
from 4)
candidate's mass x g (W = 0.045160 × 9.81 = 0.44302 = 0.44 N)
any 2sf
4
(b)
(i)
The candidate’s writing should be legible and the spelling, punctuation and
grammar should be sufficiently accurate for the meaning to be clear.
The candidate’s answer will be assessed holistically. The answer will be assigned to
one of three levels according to the following criteria.
High Level (Good to excellent): 5 or 6 marks
The information conveyed by the answer is clearly organised, logical and coherent,
using appropriate specialist vocabulary correctly. The form and style of writing is
appropriate to answer the question.
Mentions all of the following:
•
•
•
•
velocity (or speed) increases and then becomes constant (terminal velocity)
acceleration reduces to zero
forces become equal / balanced
weight (allow ‘gravity’) and drag / friction correctly identified
For 6 marks: In addition to the above, two of the following:
•
drag force increases with speed
•
(weight /downward force initially) greater than drag / friction etc
•
resultant force causes acceleration
•
Resultant force = W – drag
•
acceleration = gradient
•
acceleration is maximum (9.81) at the beginning
5-6
Intermediate Level (Modest to adequate): 3 or 4 marksThe information conveyed
by the answer may be less well organised and not fully coherent. There is less use
of specialist vocabulary, or specialist vocabulary may be used incorrectly. The form
and style of writing is less appropriate.
Mentions the two following points:
•
•
velocity (or speed) increases OR velocity (or speed) becomes constant /
terminal velocity reached
acceleration decreases OR acceleration becomes zero
ANDfor 3 marks: mentions one more valid point from the 4 above or from the 7
below:for 4 marks: at least two additional points with at least one from the ‘Forces’
list
•
acceleration = gradient
•
acceleration is maximum (9.81) at the beginning
Forces
•
weight greater than drag (before terminal velocity)
•
there is a resultant force downwards (before terminal velocity)
•
forces become equal / balanced / drag = weight
•
drag force increases with speed.
•
Resultant force = W – drag
Poor QWC may result in award of the lower mark within a band.
3-4
Low Level (Poor to limited): 1 or 2 marks
The information conveyed by the answer is poorly organised and may not be
relevant or coherent. There is little correct use of specialist vocabulary. The form
and style of writing may be only partly appropriate.
Max 3 for mention of deceleration or increasing acceleration
One valid point from list below
For two marks: Two valid points
The explanation expected in a competent answer should include a coherent
selection of the following points concerning the physical principles involved
and their consequences in this case.
Mention of the points below may influence the mark given within each category:
•
•
•
•
•
•
•
•
•
•
velocity increases
velocity becomes constant (terminal velocity)
acceleration is maximum (9.81) at the beginning
acceleration decreases (to zero)
weight greater than drag (before terminal velocity)
there is a resultant force downwards (before terminal velocity)
forces become equal / balanced / drag = weight
drag force increases with speed.
resultant force = W – drag
acceleration = gradient
valid point explaining why rapid decrease in velocity occurs when ball hits bottom of
container. E.g. resultant upward force (decelerates the ball)
Several serious misconceptions may reduce a 2 mark answer to 1
1-2
(ii)
straight line with positive gradient from origin to first dotted line
3rd mark: Allow lines that become straight with a constant negative
gradient after a curve.
Vertical line at the end is not necessary.End of line must be
between start of ‘e’ in ‘time’ and end of ‘w’ in ‘when’.
descending line (curved or straight but non-vertical) starting from a point on first
dotted line (must not have negative velocity at any point) and the line may then
become horizontal
curved line descending from first dotted line which is a continuation of the initial line
(the gradient must be decreasing initially (a curve) and the line may then become
horizontalAND extending up to second dotted line (with positive non-zero
velocity)AND no incorrect continuation of line beyond second time line
Allow correct lines beyond the second time line: continuous zero
velocity or falling below x axis and rising back to x axis (bouncing)
but not reaching a higher speed than descent
ORstraight line with positive gradient from origin to first dotted line
straight line
with positive gradient from origin to first dotted lineAND ascending curved line with
positive gradient decreasing, starting from a point on first dotted line (continuation of
first line)
extending up to second dotted lineAND no incorrect continuation of line beyond
second time line
3
[13]
E1.
Answers to this short question showed that most candidates had no real idea of how a
fluorescent light tube worked and many accounts were pure guesswork. Some of the most
common errors were, stating, in part (a), that the tube was under low pressure so that it would
not break and in part (b), believing that the electrons were directed at the coating in order to
make it glow.
E2.
Too much time was spent by candidates repeating the wording of the question and
explaining the wave particle duality. There was also a tendency to concentrate on one or two
pieces of evidence, thereby excluding themselves from gaining full marks because of the lack of
coverage. It was this aspect of the submitted answers that really governed the marks awarded,
rather than candidates making errors. It was also clear that many candidates thought it only
necessary to discuss the wave view of an electron and the particle view of an electromagnetic
wave.
E3.
Part (a) was answered well. Some candidates worked backwards from the frequency value
and failed to score full marks, not because of the order of the calculations but because they did
not include the stage of changing eV into Joules. It was also quite common to omit units for the
wavelength. There were very few correct answers to part (b) (i). Answers to part (b) (ii) were
better, but a number of good candidates misread the question and tried to determine the
wavelength.
Only the more able candidates scored well in part (c), even though there were six marking
points for the three available marks. All the misconceptions, e.g. the electrons hitting the
coating, could be listed, but in truth most candidates did not know what happened in a
fluorescent tube and wrote about anything that came to mind. A general feature of many
answers was that candidates too readily combined more than one idea in a single sentence,
thereby making their ideas unclear. It would be of benefit to most candidates to give simple
clear statements, one sentence to each idea or process, and for these to run in a chronological
order.
E5.
Part (a) was not answered well and there was much confusion as to the processes involved
in the photoelectric effect. However, a significant number of candidates confused the effect with
excitation and line spectra. Only a minority of candidates were able to explain why the kinetic
energy of the emitted electrons varied. A common response referred to the photons having a
variety of energies even though the question stated that the light had a certain frequency. Most
answers lacked significant detail such as the idea that a photon interacts with one electron and
how threshold frequency and work function are related.
This question assessed quality of written communication and it was clear that most candidates
appreciated that their answers needed a logical structure. However, few candidates were able
to give a coherent and comprehensive answer.
Part (b) generated better answers although a significant minority of candidates did not
appreciate the fact that the gradient of the maximum kinetic energy against frequency graph is
the Planck constant.
Part (c) proved more difficult than expected and a number of candidates calculated the energy
of the photon using the threshold frequency and failed to calculate the work function.
E6.
The circuit diagrams drawn by candidates in part (a) (i) were generally not done well. Many
did not include a means of varying the potential difference across the diode and the inclusion of
a load resistor was rare. Less able candidates also confused the positioning of the voltmeter.
There were very few occasions where a potential divider was used even though this is best
practice for obtaining the full characteristics for the diode.
The descriptions of experimental procedure required for part (a) (ii) were generally thorough but
some did suffer from a poor structure and this had an impact on the assessment of the Quality
of Written Communication. Many candidates did not mention anything about reverse
characteristics and it was noticeable that a significant minority did not appreciate that it was
important to obtain readings with a potential difference of less than 1.0 V.
The calculation in part (b) (i) was done well and full marks were the norm. Part (b) (ii) proved to
be not so straightforward and it was common to see candidates divide the potential difference
across the diode by the resistance of the resistor. This proved to be one of the most
discriminating questions on the paper.
E7.
Candidates usually find questions involving a description of the formation of line spectra
difficult. This proved to be the case this time and many candidates were very confused in their
answers to part (a). A common error was to mix up this effect with the photoelectric effect even
though the question mentioned the emission of photons. Many less able candidates talked
about photons being absorbed rather than electron collisions and the idea of discrete energy
levels and their relationship to the frequency of characteristic photons did not seem well
understood. This question assessed the Quality of Written Communication and candidates
tended to fail to gain marks because there was not a logical structure in the physics used in
their explanations.
Part (b) (i) was not done well and many candidates confused the incident electrons with the
orbital electrons and made statements such as ‘one of the electrons is excited and loses energy
while the other one is in its ground state’. Candidates in the main, did not link this with part (a).
Part (b) (i) and (ii) proved to be much more accessible and full marks were common. The only
common error was to use 9.0 eV instead of 8.0 eV as the energy of the photon.
E8.Part (a) proved straightforward and many candidates were able to calculate the resistance of the
putty correctly. A minority of candidates did confuse resistance with resistivity and did not
rearrange the equation from the data sheet. This question assessed significant figures and it
was clear that there are still many candidates who do not appreciate that their final answer
should reflect the precision of the data and in this case they should give their answer to two
significant figures.
Part (b) assessed quality of written communication and this question proved quite challenging
for the majority of candidates. It was extremely rare for candidates to obtain full marks and most
answers were either modest and/or limited. The circuit diagrams seen were often penalised for
careless errors such as incorrect symbols or the wrong positioning of meters.
It was rare for candidates to include a means of obtaining more than one result such as varying
the length of the putty or using a variable resistor. Descriptions were often vague and hard to
follow. Many candidates did not address the issue of precision in a convincing way and failed to
describe how they would make all the measurements needed. It is clear from this paper and
from previous papers that candidates find describing experiments difficult and would benefit
from some practice of this skill.
E9.
A significant proportion of candidates found part (a) difficult. It seems that many candidates
were not familiar with an appropriate experiment that enables the variation of a thermistors
resistance with temperature to be investigated. While many drew a correct circuit diagram, few
were able to explain suitable techniques for varying the temperature of the thermistor. It was
common to see answers that confused this experiment with one that investigated the I –
Vcharacteristics of a filament lamp. This led candidates to suggest that it was appropriate to
investigate resistance change by using increasing current to change the thermistor resistance.
There was also much confusion as to how resistance was to be determined and the use of a
graph of current against voltage was a regular response. Candidates incorrectly stated that they
would determine the resistance of the thermistor by measuring the gradient of the graph. This
would not be an appropriate method as the graph would be a curve and the gradient of the
curve is not the resistance. It was extremely rare for water baths to be used for heating the
thermistor and also many did not explain how they would measure the temperature of the
thermistor. Many candidates did not address the issue of precision in a convincing way and
failed to describe how they would make all the measurements needed. It is clear from this paper
and from previous papers that candidates find describing experiments difficult and would benefit
from some practice of this skill.
In contrast parts (b) and (c) were generally answered well and full marks were frequently seen.
Less able candidates found it difficult to explain clearly the effect on the voltmeter reading if the
battery did have an appreciable internal resistance. There is some evidence that candidates did
not understand the meaning of the term negligible.
E10.
Descriptive questions on quantum phenomena have caused candidates major problems in
previous papers. Therefore, it was good to see so many confident answers to this question.
Candidates seemed much more confident explaining excitation and line spectra than they are
describing aspects of the photoelectric effect. Far less confusion was evident and a number of
answers were awarded marks in the top band – a significant increase on previous questions
that assessed the quality of written communication. Some less able candidates incorrectly tried
to include a discussion of threshold frequency but this was comparatively rare. The correct use
of technical terms such as ionisation and excitation were seen frequently and there was strong
evidence that this aspect of quantum phenomena is more widely understood that is the case in
other related areas of the specification.
Part (b) was generally answered well, although a minority of candidates incorrectly related the
ionisation energy of hydrogen to a mole of hydrogen atoms. The conversion of electron volts to
joules caused few problems and the majority of candidates appreciated that their answer should
be quoted to three significant figures.
E11.
Part (a) (i) required students to draw a suitable arrangement for investigating the variation
in resistance of a piece of wire with temperature. Many students drew an appropriate circuit and
misplaced voltmeters were far less in evidence in circuit diagrams. However, the majority did
not show how the temperature of the wire was to be varied, in spite of being given the hint that
the temperature range should be varied between 0°C and 100°C.
The description of the experiment required in part (a) (ii) was answered better than has
previously been the case. Nevertheless, a significant proportion of students did not provide
suitable methods for temperature variation. Suggestions such as ‘vary the temperature using a
thermistor’ or ‘direct use of a Bunsen burner’ were not uncommon. It was clear that some
students did not appreciate that the wire could be safely placed in a water bath.
Part (b) on critical temperature was answered well.
E12.
Part (a) required students to describe the use of an oscilloscope to measure peak voltage
and frequency of an alternating current supply. This was answered well by a good proportion of
students and many were confident in their description of the use of the time base to determine
frequency and the y-gain to measure peak voltage. In a number of good quality answers
students mentioned switching off the time base and measuring peak to peak voltage so as to
find an accurate rms voltage. It was evident however, that a minority of students were unfamiliar
with the use of an oscilloscope and consequently gave very vague answers which scored few
marks.
The calculation of rms and peak current were well done with the only common error occurring
when students assumed that the 12 V quoted in the question referred to peak voltage. Those
doing this were not heavily penalised as their answers were carried forward in the subsequent
calculations.
E13.In this question candidates needed to understand what is meant by an ohmic conductor and to
describe an experiment to determine whether a particular component exhibited the necessary
properties to be classed as this type of conductor. A significant proportion of candidates could
not state what is meant by an ohmic conductor and responses such as “obeys Ohm‘s Law” and
“something with resistance” were quite common.
A high proportion of correct circuit diagrams were seen in part (b)(i) and incorrectly placed
voltmeters were rare. The main omission was a means of varying the current in the circuit. The
experimental design caused problems and less than 15% of candidates wrote answers that
qualified them for the top band. Some described the wrong experiment such as investigating the
effect of temperature on the resistance of a thermistor. Those that did describe a correct
experiment tended not to fully develop their answer. It was expected that a top band answer
would have details of how a graph of results might be interpreted and in many cases this was
only done in a very superficial manner. Candidates who did refer to a straight line indicating
direct proportion often failed to mention that for this to be true the line must go through the
origin. There was also a tendency for them to state that the gradient of the graph is equal to the
resistance. While this is true for a straight line graph going through the origin, it is not generally
true and it was clear from a significant proportion of responses that candidates are not aware of
this. It was good to see evidence of candidates planning their answers and given that they find
these types of questions a challenge, this is a practice to be encouraged.
The remaining part of the question required knowledge of superconductors and although a high
proportion of candidates failed to give a convincing use of superconductors the important
property of a superconductor and the significance of critical temperature proved to be well
understood.
E14.This question on particle classification generated some very impressive responses. Many
candidates proved to be quite confident in their extended writing and top band answers were
seen more frequently than has been the case in the past, particularly when questions refer to
the photoelectric effect or line spectra
The main confusion that weaker candidates seem to have was an appreciation of which groups
are affected by the strong nuclear force – a significant proportion seemed to think that this was
only baryons
The most common omission in good answers was the identification of a similarity between
hadrons and leptons. Overall however, the question worked well and candidates clearly enjoy
this aspect of the specification and evidence for this is found in the confidence shown in many
of the answers.
E16.
Half of the candidates gained both marks for part (a). Nearly all pointed out that force is
proportional to extension but half did not mention the ‘limit of proportionality’. Candidates need
to ‘look for a second mark’.
Candidates had to apply their knowledge of Hooke’s law in part (b) (i). A significant number of
candidates did not have a workable method and scored zero on this question. Many candidates
picked up two marks by describing a simple comparison between extensions due to standard
masses and the rock sample. A correct graphical approach and a point about accuracy were
required for full marks. This question could perhaps form the basis of a practical activity to
illustrate the significance of Hooke’s law in measuring mass or weight. A large number of
candidates believed that the Young modulus of the spring should be found.
In part (b) (ii) most candidates knew how to stop the apparatus toppling over but a significant
number could not describe this well enough to get the first mark, i.e. ‘put a weight on the stand’
did not gain marks but ‘put a weight on the base of the stand’ did. For the second mark, it was
expected that candidates would give a correct explanation in terms of moments but hardly any
candidates spotted this.
E17.
Most scored very well on parts (a) (i) and (ii), which were fairly straightforward questions,
though occasionally the answers to (a) (i) and (a) (ii) were given the wrong way round.
In part (b) Quality of Written Communication was assessment. Many candidates did not specify
a distance measuring instrument (a ruler); perhaps failing to state the obvious.
Very few recognised the need to specify a suitable number of different loads over the complete
range. This would be important in order to obtain the true shape of the curve; six marks were
only awarded if the candidate specified seven or more loads.
Many candidates forgot to include the unloading of the rubber cord in their answers and would
have benefited greatly from re-reading the question and their answer here.
Candidates in a few centres appeared to use mnemonics to remember the elements necessary
in answering this type of question; this seemed to work quite well.
E18.
Part (a) (i) was answered well. Candidates immediately recognised a ‘suvat’ question and
performed the calculation with no difficulty.
It was a similar story in part (a) (ii) with most candidates having no trouble in gaining both
marks.
The responses to part (b) were, in general, a little disappointing. Responses that simply
indicated that the ball decelerated and that balanced forces caused terminal velocity could
achieve a maximum of four marks. For the higher marks (five or six), candidates needed to
explain that the deceleration was decreasing and the drag force decreased as the ball slowed
down. These more sophisticated answers discussing the forces acting were rare.
Some candidates compared different quantities, eg ‘acceleration balanced out the weight’.
Some clearly thought that the graph showed acceleration not velocity.
Unfortunately, almost every candidate felt the need to describe the motion of the ball before it
entered the liquid before embarking on answering the question. In many cases half or more of
the answer space was used up before any marks were scored. Perhaps many candidates felt
this was a suitable introduction to their answer. However, as a general rule, marks will not be
awarded for correct physics statements that do not address the question. Inclusion of irrelevant
detail in this case resulted in an excessive number of candidates requiring additional sheets to
complete their answers.
E19.
Part (a) assessed the candidates’ quality of written communication. Most responses were
lacking in detail and there was a general lack of awareness of what is required in a question
such as this. The question asked how the data to determine the Young modulus could be
obtained accurately. A good response would mention the quantities needed and the measuring
instruments required with an indication of how the apparatus is arranged.
Many candidates did not list all the measurements (original length, extended length, diameter)
or the quantities derived from these (extension and cross sectional area) that would be needed
for the calculation of Young modulus. Failure to state that diameter or cross-sectional area
would be measured limited the candidate to two marks out of six.
Candidates were also expected to make a comment about accuracy and to get beyond two
marks they needed to mention some form of repeat or the use of a range of masses or the use
of a wire of 1.0 m or more.
The specification states that candidates should know a simple method for the determination of
the Young modulus. This implies that they do not need to be familiar with Searle’s apparatus.
Some candidates scored well when giving a detailed account of Searle’s. However, those who
seen Seale’s apparatus but only partially understood how to use it, tended to fare less well than
those who described stretching a wire along a bench. It should be noted that the phrase ‘simple
method’ does not imply that a non-graphical method will suffice. Many candidates described
substituting one-off measurements into the Young modulus equation. An accurate method, at
least in a school laboratory, should involve using a range of loads and extensions. We would
recommend that centres who have Searle’s apparatus do demonstrate it and give students the
opportunity to use it. However, the simpler method of stretching horizontally on a bench can be
presented as the preferred option for a descriptive question such as this for all but the most able
and meticulous students.
Diagrams produced by candidates here tended to lack detail and labelling and many did not go
on to state that the load or force had to be found from the mass.
In part (b) (i), the line of best fit was drawn well by 55%. Some drew a straight line but did not
produce a curved section at the top. Some did not draw the line going through the origin.
However, it was felt that in this case candidates should expect a stress-strain graph to go
through the origin and should have extended to the origin. Best fit lines are taught extensively at
KS3 and KS4. However, the evidence suggests that candidates continue to lose marks on these
at AS level so a lot of practice is needed.
For part (b) (ii) most candidates did very well and picked up three or four marks. A significant
percentage of candidates who had drawn an incorrect best fit line did pick up full marks for the
gradient calculation. Of those who did not, many chose the wrong unit eg Nm–1, Nm or ‘pa’
rather than Pa. Some candidates could have been awarded a method mark if they had drawn a
triangle as evidence that they where calculating the gradient. Many candidates could have set
out their answer in a much clearer manner.
E20.
For part (a), most candidates found the increase in gravitational potential energy without
any problems.
In part (b) (i), half of all candidates realised that the gain in kinetic energy could be calculated
from the loss in gravitational potential energy. Many candidates wrote down the equation for
kinetic energy and were unable to make progress from there.
A large majority of candidates were able to rearrange the kinetic energy equation in part (b) (ii)
and calculated successfully the speed from their answer to part (b) (i).
The direction of the arrow did not cause any problems in part (c). However, the placement of
arrow did. The tail of the arrow should originate close to soles of gymnast’s feet but the majority
placed it to the side, above or below this position.
Part (d) was quite a tricky question, but it was answered well by a large number of candidates
using a = Δv/t with their value of speed from part (b) (ii).
In part (e), a large number gained four marks or more on part (e) and the Quality of Written
Communication was generally very good. The most common reason for not reaching the higher
marks was focusing only on transformations and not mentioning the work done by or on the
gymnast in order to reach a greater height.
E21.
Some candidates forgot to answer the second part of the question and did not make
adequate reference to the features of the stationary wave shown. The first part (how a
stationary wave is formed) was answered well. Many candidates used the term ‘superimpose’
instead of ‘superpose’ and typically a candidate would lose a mark for this.
E22.
Part (a), an extended answer question, yielded the highest marks of any so far on this
examination. It was a standard situation and candidates were very familiar with the physics so,
the majority gained more than half marks. It was not too difficult to get five marks out of six
however; full marks were only given to the most complete of responses.
It was pleasing that only a few misinterpreted the question and chose the wrong path;
inappropriate discussion of ‘gratings’ was only seen a few times. The majority of candidates still
recommend protecting the eyes from laser radiation by wearing ‘goggles’. If the candidate
insists on giving this advice, they must specify ‘goggles designed to protect the eyes from laser
radiation’ or words to that effect, since ordinary lab goggles would provide no protection.
Marks were still sometimes lost due to candidates not specifying measuring instruments.
However, there was a marked improvement on previous experimental description questions.
Even the humble ‘ruler’ should be specified if it is to be used.
Part (b) was a common question and perhaps, therefore, it should have yielded a higher
percentage of full-marks answers. The most common error was to say that the two sources are
‘in phase’. However, it should be stressed that coherent sources have a fixed phase
relationship, so they are not necessarily in phase.
Many candidates did not include the single slit and many did not label the slits in answer to part
(c).
A significant number did not attempt the question at all. Surprisingly, less than half scored any
marks at all on this question.
In part (d), some candidates thought that the fringes for white light would be further apart. This
would only be true if the laser were red; the candidate would have to state this assumption to
gain the mark.
Some lost marks because they did not make it clear which light source they were referring to.
Most candidates gained the mark in part (e) for mentioning destructive interference but did not
go on to explain that the cancellation is caused by the waves meeting in antiphase or with half a
wavelength path difference.
E23.
Part (a) was done well by most students. However, many would have benefitted from using
a protractor to get the angles between the zero order and the two first-order beams roughly
equal.
In part (b), the basic requirement is that students know that dark lines (absorption lines) are
seen on the spectra from stars and that these reveal elements present in the outer layers of the
star. The mark scheme also credited other uses of a stars spectrum. Many students had the
idea that spectral lines revealed elements but few knew about absorption lines. This is an area
where students who have taken PHYA1 first may have an advantage since they have studied
atomic energy levels and may have seen absorption spectra.
Labelling a laser, diffraction grating and some sort of screen or suitable detector was all that
was required for the two marks in part (c) (i). Many students missed out the screen. Some had
double slits instead of a grating.
Part (c) (ii) was, in general, poorly answered. Many students did not seem to be familiar with
this practical and instead described a two-slit approach to measuring wavelength. Those who
seemed familiar with the procedure tended not to fully answer the question which asked for
details of all the measurements and necessary calculations. The candidate who leaves out
these details is unlikely to be able to score more than two marks out of six even if they have
given a reasonable general description of the experiment. For example, they must include
details of how the angle is to be measured eg by measuring the distance between the zero
order and the first-order beam (using a ruler) and the distance between the screen and the
grating. They must then use tan θ = O/A to calculate the angle. Where students knew which
equation to use, they tended to know insufficient detail to score more than a few marks. Of
those students who did describe the use of a grating, many did not know the meanings of the
symbols in the equation eg, d was often thought to be the distance between grating and screen
and n, the number of lines per mm or even the refractive index of air. Many described
measuring the grating spacing with micrometers or metre rules, forgetting that the question
stated that the lines per mm are known.
In short, many of the students who took this exam seemed poorly prepared for this type of
question. They were, in some cases, able to produce an answer from a past paper for a closely
related, but significantly different, question. Many seemed unaware of the style and quality of
answer expected.
Most answers were vague, the literacy level was generally poor and there was a lack of detail
regarding the measurements and what should be done with them. This is often the case in the
January examination, but it is possible to improve the necessary skills even in the short
preparation time available. A few structured lessons on answering this type of question can to
be incorporated into schemes of work, allowing students to be fully aware of the expectations.
E24.This was a very accessible question given that there are several past paper questions that
address the same issue of the formation of stationary waves.
Candidates did very well on this question but there was a lack of understanding of some wave
terminology evident. Candidates often correctly explained that two progressive waves travelling
in opposite directions give rise to a stationary wave. However, they often described the waves
as having a constant phase difference and being coherent. Many also thought that a node is
formed by a peak cancelling a trough and an antinode is formed by a peak meeting peak or a
trough meeting a trough.
An antinode is formed at a position where the displacements of the two waves are always in the
same direction and of equal magnitude, they are not always peaks or troughs. A node is formed
where the waves always cancel and this is not only due to a peak meeting a trough but is due to
the waves having equal and opposite displacements at the position of the node. Another
common misconception was that two troughs meet to give destructive interference.
The two progressive waves have a constantly varying phase difference. It would be correct to
say that at the position of a node, the two waves are always in antiphase and they arrive at
antinode in phase.
E25.(a)
Many students seemed unaware that the volume of a sphere was given on the data sheet.
Because of this they guessed at the formula often electing to use π2.
Many of those who did find the correct formula still did not manage to calculate the correct
volume due to numerical errors.
There was also the usual issue with candidates believing mass and weight are the same
thing and giving the weight in kg. Many did not round their answer to the correct number
of significant figures which should have been 2.
(b)
Some very good, detailed and correct answers here. However, a common error was to
confuse decreasing acceleration with deceleration.
(i)
Many candidates started well and then at the end started padding out their answer,
often with incorrect and contradictory statements, e.g.: ‘so therefore the longer the
time, the slower the velocity and the acceleration.’
Again, candidates were sometimes not accurate and careful in describing motion
and gave answers similar to the following:‘As the gradient of the graph decreases
this is showing a decrease in velocity and acceleration’.‘After half of the time has
passed, the ball stops and travels at a constant speed’.‘As the speed of the ball
increases, the resistive force increases, resulting in the ball slowing down’.
The was also the usual problem with comparison of different quantities, a typical
example being:
‘At first the drag acting on the ball is greater than the acceleration, so the velocity
increases until its equal to the drag force.’
(ii)
The examiners bold looking for a straight line to begin with. However, many
candidates produced a curve showing significant air resistance.
It is possible that the ball bearing could hit the water at a speed less than its terminal
velocity in oil. Therefore candiates who correctly described this were able to get full
credit – though perhaps this answer was not the most sensible approach.
There were many wrong answers showing the ball bearing‘s acceleration
decreasing in air or increasing in the water.
The challenge is to get students to accurately show how a given quantity changes
with time for a body in motion. A teacher could choose a range of examples of
objects whose velocity and acceleration change with time and ask students to
sketch and describe them. They could then display the results using a visualizer or a
camera linked to a projector in order to facilitate discussion.