Set-B
MAHESH TUTORIALS I.C.S.E.
GRADE - X (2015-2016)
Exam No. : MT/ICSE/PRELIM - I -Set -B 007
PHYSICS
SCIENCE Paper - 1
(One hour and a half)
Answers to this Paper must be written on the paper provided separately.
You will not be allowed to write during the first l5 minutes.
This time is to be spent in reading the Question Paper.
The time given at the head of this paper is the time allowed for writing the answers.
Section I is compulsory. Attempt any four questions from Section II
The intended marks for questions or the parts of questions given in brackets [ ].
SECTION – I (40 Marks)
Attempt all questions from this section.
Question 1
(a)
Name any two different units of energy (other than SI unit and its multiples
subunits).
[2]
(b)
A light mass and a heavy mass have equal momentum. Which will have
more kinetic energy and why?
[2]
(c)
Give one example each for the conversion of
(i) Sound energy to electric energy.
(ii) Chemical energy to light energy.
[2]
What is the effect of kinetic energy of a moving car if:
(i) its mass is doubled.
(ii) its velocity is halved.
[2]
In a single fixed pulley actual mechanical advantage is less than 1 and
velocity ratio is 1 even then it is widely used. Give two reasons.
[2]
(d)
(e)
Question 2
(a) Arrange the following in ascending order of frequency:
X-rays, radio-waves, IR radiation, -rays and UV-rays.
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(b)
State any two differences between total internal reflection from a prism
and Reflection from plane mirror.
[2]
(c)
When a ray of light is going from denser to rarer medium such that its
angle of refraction is 90º, name the corresponding angle of incidence.
(d)
(i)
(e)
A ray of light falls normally on one face of a prism at an angle 45º. If
critical angles for the material of the prism is 45º, trace the path of
[2]
What are the general characteristics of the image produced by a
concave lens.
(ii) A concave lens can be regarded as a combination of a glass slab and
two triangular glass prisms. Use this fact to show how it refracts two
parallel incident rays.
[2]
[2]
rays.
Question 3
(a) Draw a graph between displacement for mean position and time for a
body executing free vibration in (i) vacuum (ii) in a medium
[2]
(b)
A radar is able to detect the reflected waves, from an enemy aeroplane,
after a time interval of 0.02 milliseconds. If the velocity of the waves is
8
3 × 10 m/s, calculate the distance of the plane from the radar.
[2]
(c)
Calculate the heat energy required to melt 10 kg of ice at 0ºC and become
water at 0ºC. (Take latent heat of ice as 334 kJ/kg. Express your answer
in SI unit.)
[2]
(d)
What is the effect on the following quantities when a wave travels from
one medium to other? (i) wavelength (ii) velocity (iii) frequency.
[2]
Why the base of cooking pan is made thick?
[2]
(e)
Question 4
(a) Can you connect resistors of 2 , 3  and 6  to produce an effective
resistance of 4  ? If yes, how ?
[2]
(b)
Why is the earth pin plug always made longer and thicker ?
(c)
A current I passes through a circular loop C, and solenoid AB as shown
in the figures :
I
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C
A I
[2]
B
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(i)
What is the polarity of:
1. The face of the loop you are looking at ?
2. The end B of the solenoid?
(ii) What is the direction of the magnetic field at the centre of the loop? [2]
(d)
A certain radioactive nucleus emits a particle that leaves its mass
unchanged but increases its atomic number by one. Identify the particle
and write its symbol.
[2]
(e)
Mention ,  and  in:
(i) Increasing order of their penetrating power.
(ii) Decreasing order of their ionising power.
[2]
SECTION - II (40 Marks)
Attempt any four questions from this section
Question 5
(a)
A boy of mass 50 kg runs upstairs and reaches the 8 m high first floor in
five seconds.
calculate :
(i)
the force of gravity acting on the boy.
(ii) the work done by him against gravity.
(iii) the power developed by the boy.
[3]
(b)
Why is the longer handle of water pump preferred?
[3]
(c)
Figure given below shows the combination of a movable pulley P 1 with
a fixed pulley P2 used for lifting up a load W.
i)
State the function of the fixed
pulley P2.
ii)
If the free end of the string moves
through a distance x, by what
distance is the load W raised ?
iii) Calculte the force E to be applied to
just raise the load W = 20 kgf ?
Neglect the weight of the pulley P1
and the friction.
Question 6
(a)
T
P
2
T
P1
T
E
W
[4]
Load
The ray diagram given on the next page
illustates the experimental set up for the
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determination of the focal length of a
converging lens using a plane mirror.
(i)
State the magnifications of the image formed.
(ii) Write two characteristics of the image
formed.
O
(iii) What is the name given to the
distance between the object and
the optical centre of the lens in
[3]
the above diagram?
(b)
Draw a properly labelled ray diagram showing the real and apparent
[3]
position of a coin in a tank filled with water.
(c)
The diagram shows an object “O”, and
its image ‘I’ formed by a lens. In the
diagram, draw the lens and the rays to
show how is the image formed. Mark
focus of the lens and name the lens.
O
[4]
I
Question 7
(a) A man stands at a distance of 25 m from a high wall. He hears the echo
produced from the high wall, by blowing a whistle.If the velocity of sound
in air is 330 m/s, what would be the time interval between the sound
produced by the whistle and the hearing of the echo.
[3]
(b)
How can one distinguish the sound of two musical instruments even if
they are of same pitch and same loudness ?
(c)
Two simple pendulums A and B, of different lengths, are suspended from
the same string as shown in the figure given below. When A is displaced
from its mean position and let go, it is found that B also starts vibrating.
(i) Name the phenomenon responsible for
the vibrations of B.
(ii) does the frequency of vibrations of B
depend on its own length or on the
frequency of vibrations of A.
(iii) What would happen to the amplitude of
vibrations of B if its length was made
B
equal to that of A ?
A
[3]
(iv) Name the phenomenon that occurs
when the length of B is made equal to that of A.
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Question 8
(a)
In the figure , A, B and C are three ammeters. The ammeter B reads as
2
0.5 A. Calculate.
(i)
The reading in ammeter A and C.
(ii) The total resistance of the circuit.
6
B
A
3
C
[3]
[3]
(b)
Draw labelled diagram of a three-pin socket.
(c)
A wire of uniform thickness with a resistance of 27  is cut into three
equal pieces and they are joined in parallel. Find the resistance of the
parallel combination.
[4]
Question 9
(a) 1080 g of ice at 0ºC is mixed 1080 g of water at 80ºC. Calculate the final
temperature of the mixture.
[3]
(b)
How do the wine/juice bottles under water, remain safe against freezing
in very cold countries?
[3]
(c)
Calculate the time taken by an immersion heater which supplies energy
at the rate of 7000 J / minute to raise the temperature of 5kg of water
from 22ºC to 47ºC.
[4]
Question 10
(a) What are ,  and  radiations composed of ?
[3]
(b)
What is the effect on the electron beam particles in a cathode ray tube if
1. a hotter filament is used ?
2. the anode voltage is increased?
Name one device in which the cathode ray tube is used.
[3]
(c)
A certain nucleus ‘X’ has a mass number 15 and atomic number 7. Find
the number of neutrons. Write down the nuclear changes that take place
when X loses:
(i) one proton
(ii) one -particle and
(iii) one -particle.
[4]
All the Best 
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Set-B
MAHESH TUTORIALS I.C.S.E.
ICSE X
SUBJECT : PHYSICS
Exam No. : MT/ICSE/Prelim-I Set B 007
Marks : 80
Time : 1½ hrs.
Model Answer Paper
SECTION - I (40 Marks)
A.1.
(a) Two different units of energy are kilowatt hour (kWh) and electron volt
(eV).
[2]
(b)
As you have read that kinetic energy E = P2/2m i.e., for two bodies of
k
different mass and equal momentum, kinetic energy is inversely
proportional to mass. Therefore,light mass body will have more kinetic
energy.
[2]
(c)
(i) Microphone
(ii) Candle
[2]
1
mv2
2
(i) If mass m is doubled, the kinetic energy gets doubled.
(ii) If velocity v is halved, the kinetic energy becomes one-fourth.
[2]
(d) We know that kinetic energy =
(e)
(i)
It is always easier to apply effort in the downward direction rather
than upward direction. Thus,, it helps in changing the direction of
effort.
(ii) One can use one’s own body weigh while applying effort in downward
direction.
[2]
A.2.
(a) Frequency of radiowaves < IR radiation < UV rays < X-rays < -rays.
(b)
Total internal reflection
from a prism
[2]
Reflection from a plane
mirror
1. It takes place when light travels 1. It takes place for any angle of
from a denser medium to rarer
incidence.
medium with the angle of
incidence greater than the
critical angle.
2. Total internal reflection is total 2. Reflection is partial because a
with no absorption of light.
part of incident loght is absorbed
[2]
by mirror.
(c)
The angle of incidence under this condition is called critical angle for
the given pair of media.
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(d)
(i) The image produced by a concave lens is virtual, erect and diminished.
(ii)
[2]
(e)
A
45º
P
Q
B
90º
90º 45º
45º
90º
C
S
[2]
DISPLACEMEMENT
A.3
(a)
Time
t
Displacement
Free vibration (in vacuum)
Time t
Vibration in medium
[2]
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(b)
Set-B
Let d be the distance of enemy plane from the radar. The waves
from the radar travel a distance (d + d) = 2d before beign detected.
The time for this purpose is 0.02 millisecond (or 2 × 10 –5 S).
Hence, velocity of waves is
v 
2d
t
2d
= 2  10 –5 s
2d
8
2  10 –5 s = 3 × 10 m/sec
d
(c)
(d)
Q
Given m
L
Q
=
=
=
=
=
=
= 3 × 108 m/s × 2 × 10–5 s/2
= 3 × 103 m = 3 km
[2]
mL
10 kg
334 kJ/kg = 334 × 103 J/kg
10 kg × 334 × 103 J/kg
3340000
3.34 × 106 J.
[2]
When a wave travels from one medium to other, its:
(i) Wavelength changes
(ii) Velocity changes
[2]
(iii) Frequency remains same.
(e)
Its thermal capacity increases, thus it can impart sufficient heat energy
for cooking even at low temperature.
[2]
A.4
(a) Connect the 3W and 6W resistors in parallel.
Their equivalent resistances will be
3   6
 2
3   6
Connect 2  resistor in series with the combination of 23 . Thus, it will
produce an effective resistance of 4 .
[2]
(b)
(i)
The earth pin being thicker can never enter in live or neutral sockets.
Thus, there will be proper electrical connection.
(ii) The longer earth pin, gets connected to earth terminal first, as
compared to live or neutral pins because in case of any leakage of
charge, the earth pin will conduct the charge to the earth. This
ensures that the user will not get electric shock.
[2]
(c)
(i)
(1) South pole
(2) North pole
(ii) Perpendicular to its plane directed inwards.
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(d)
(e)
The particle is of mass number zero and atomic number –1. It is beta
particle or electron number –1. It is beta particle or electron. Its symbol
º
º
 or e
1
1
[2]
(i)  <  < 
(ii)  >  > 
[2]
SECTION – II (40 Marks)
A.5.
(a) Given mass of the boy, m = 50 kg
Heigh of the floor, h = 8m , t = 5 s
(i) Force of gravity acting on the boy
= mg
= 50 kg × 10m / s2
= 500 N
(ii) Work done by him against gravity,
W = mgh
= 500 N × 8 N
= 4000 J
(iii) Power developed by the boy
W 4000 J

t
5s
= 800 J/s
= 800 W
=
(b)
[3]
Longer the effort arm of the handle of water pump, lesser is the effort
rewuired to operate the pump because increase in the effort arm
[3]
increases the mechanical advantage.
(c)
i)
The function of the fixed pulley P2 is to apply the effort in a convenient
direction (i.e. downwards)
ii)
The load W will raise by a distance
iii) E = T and W = 2T
 force needed E =
x
.
2
W 20
=
= 10 kgf
2
2
[4]
A.6
(a)
(i)
Same size as object.
(ii) Real and inverted.
(iii) Focal lenght.
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(b)
r
A pparent
depth
Real
depth
i
I r
Rarer
D enser
i
C oin (O )
[3]
L
(c)
O
F
The given lens is concave.
[4]
L
A.7
(a) Given d = 25 m, v = 330 m/s, t = ?
time interval between the sound produced by the whistle and the hearing
of the echo.
2d
2  25m
t = v  330 m /s  0.151s
[3]
(b)
Two different musical instruments of same pitch and same loudness
emit secondary vibrations alongwith the fundamental vibrations. The
wave from of sound from an instrument depends on the presence of
subsidiary vibrations along with the principal vibrations.
[3]
(c)
(i) Pendulum B vibrates due to the phenomenon of forced vibrations.
(ii) The frequency of vibrations of B depends on the frequency of
vibration of A.
(iii) Amplitude of B increases.
(iv) Reasonance.
A.8
(a) (i)
[4]
Given, current in 6  resistor I1 = 0.5 A
 p.d. across 6  resistor
=
0.5 × 6 = 3V
The p.d. across 3  is also 3 V
 Current in 3  resistor I2
3
=1A
3
 Total current drawn
=
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= I1 + I2
= 0.5 + 1 = 1.5 A
(ii) Equivalent resistance in parallel combination,
1 1 1 1 2 3 1
  
 
R 6 3
6
6 2
 R=2
 Total Resistance of the circuit
= 2+2
= 4
(b)
Hole to insert
neutral pin of
the plug
[3]
Hole to insert
earth pin of
the plug
Hole to insert
live pin of
the plug
[3]
(c)
If a wire of resistance 27 W is cut into three equal pieces, the
1200
= 9 W. On joining them in
40
parallel, the resistance of parallel combiantion (R eq) will be given by
resistance of each piece will be
1
1 1 1 3
   
R eq
9 9 9 9 or Req = 3
[4]
A.9
(a) Amount of heat energy required to melt
1080 g of ice at 0ºC into water = mL
= 1080 × 80 cal/g = 86400 cal
Amount of heat lost by 1080 g of water at 80ºC
= mcT
= 1080 g × 1 cal / g/ºc × (80–0)ºC
= 86400 cal
This is precisely the amount of heat lost by 1080 g of water at 80ºC to
bring down its temperature to 0ºC.
So, the temperature of the mixture will be 0ºC.
[3]
(b)
(c)
In cold countries wine/juice are placed under water to prevent freezing
because water has to release large amount of heat (4.2 J for each gram
of water) to lower its temperature to the same extent as juice and hence
the chances of freezing are reduced.
[3]
Let the required time be t minutes.
So, the heat produced by heater in t minutes
=
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 J 
7000 
 × t (min)
 min 
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= 7000t J
Heat absorbed by water
= m × c × T
= 5 kg × 4200J/kgºC × (47 –22)ºC
= 52500 J
Heat generated by heater
= Heat absorbed by water
7000t = 525000
t
=
t
=
525000
7000
75 minutes
[4]
A.10
(a) -rays are the helium nuclei in which each atom is made up of two
protons, two neutrons and no electrons around it.
-rays are composed of stream of electrons.
-rays are the electromagnetic radiations of short wavelength of the
order 0.1 Å to 5 Å. They are photons of rest mass zero.
[3]
(b)
Effect on the beam particles:
1. When hotter filament is used, bulk of cathode rays produced is
increased. This results in brighter image.
2. When anode voltage is increased, the electrons speed up and strike
the screen with large speeds. This may damage the screen.
Cathode ray tube is used in cathode ray oscilloscope and
in television.
[3]
(c)
Mass number
= No. of protons + No. of neutrons
 No. of neutrons
= Mass number – No.of protons
= 15 – 7 = 8
Element X is written as
(i)
15
X .
7
When one proton is lost, the mass number and atomic number both
decrease by 1.
15
X
7
14
1
Y  P
8
1
(ii) When one -particle is emitted, the mass number reduces by 4
whereas the atomic number reduces by 1.
15
X
7
ii)
15
º
Y 

8
–1
When one -particle is emitted, the mass number reduces by 4
whereas the atomic number reduces by 2.
15
X
7
11
4
P 
( - particle)
5
2

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[4]