Light and Sound Revision
NAME:___________________________
Test hints: Read each question carefully to be clear whether the question is referring to light
or sound. Consciously consider this; either highlight it or write this down.
The diagrams below show simplified images of the two main types of waves we have been
learning about in this topic. Examine each of the waves and answer the questions that follow
Wave 1
C
R
C
R
C
C
T
C
T C
R
C
R
C
R
C
R
T
C
T
C
T
C
T
c=compression and R=rarefaction
c= crest and T=trough
wavelength
The wave above is a ….. wave (From the list below, tick all that might apply):
Transverse
Mexican
Light
 Pressure


Sound
Compression

Longitudinal
In the diagram above label the crests with a C’s and troughs with T’s.
Label the drawing to show a wavelength. (see above)
At what speed with this wave travel in air? (use the SI unit) ~340m/s
How do the particles move as the wave passes? They vibrate back and forth
In which direction does the energy move? From left to right
wavelength
Wave 2
C
C
T
C
T
C
T
C
T
C
c= crest and T=trough
T
c= crest and T=trough
wavelength
The wave above is a……………. wave (From the list below, tick all that might apply):
Transverse
Sound
Longitudinal

Mexican
Pressure
Light
Compression

1
In the diagram above label the crests with a C’s and the troughs with T’s.
Label the drawing to show a wavelength. (see above)
At what speed with this wave travel in air? ~300 000 000 m/s or 3 x 108 m/s
In which direction does the energy move? From left to right
Questions about waves in general:
1. a) Once a wave has been generated what aspect(s) of that wave will be unchanged as it
passes into different media? Its frequency
b) Once a wave has been generated what aspect(s) of that wave will change as it passes into
different media? Its speed and its wavelength.
2. When comparing two waves travelling through the same medium, if wave X has a higher
frequency than wave Z then wave X will have a shorter wavelength compared to wave Z.
3. If you put your fingertip in a pool of water and repeatedly move it up and down, you will
create circular water waves that move out from that point. What will happen to the
wavelength of these waves if you move your finger up and down more slowly (or less
frequently)? The wavelength will get longer/increase
4. If the amplitude of a wave is increased 10%, what happens to the wave speed?
The speed is unchanged. Speed determined by the medium through which the wave travels,
not the amplitude of the wave.
5. Can a transverse wave be produced in a Slinky (toy)?
Yes …we did this in class
Sound Review Questions
1. What does the amplitude of a sound wave determine about a sound? Its intensity
which is a measure of volume and which we perceive as loudness.
2. What does the frequency of a sound wave determine about a sound? PITCH
3. Explain how Echolocation works.
In an animal a high frequency sound is produced; it travels through air until it hits
something that reflects it back to the animal. The animal can tell how long it took
the sound waves to return and given this they can determine the distance of the
object from them.
Humans can use echolocation by creating a loud sound and timing how long it takes
the eco to return to their ears. This time halved because the object is only half this
distance away. The equation v=d/t or d=v x t is used to calculate the distance of
the object located. (speed of sound(v) in a medium is known)
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4. Generally how does the speed of sound compare between solids, liquids and gases.
In general …………….speed in a solid > speed in a liquid > speed in a gas
5. In very general terms why is the speed of sound in a gas slower?
Sound travels through particles and in a gas the particles are further apart so sound
will be transmitted more slowly.
6. What two factors will most influence the speed of sound as it travels through a solid
medium?
The elasticity of the medium and the inertial resistance.
7. Which of the following is objective? Intensity of sound or loudness of sound?
Intensity of sound (as determined by amplitude) is objective and loudness is
subjective
Light Review Questions
1. In dry air at 25 degrees Celsius, how does the speed of x-rays compare with the speed of
radio waves. They are the same
2. Give a key use of each type of EMR.
Radiowaves e.g TV and FM radio
Microwaves e.g heating food, satellite signals
Infrared e.g remote controls, heat lamps, toasters
Visible e.g vision, rainbows, optical fibres
Ultraviolet e.g sterilization (sunburn)
X ray: e.g.medical imaging, airport security
Gamma ray : e.g. radio therapy for cancer treatment
3. What happens to the amount of energy of waves as the frequency of the wave increases?
The amount of energy increases
4. What does the frequency of the light wave determine about the light?
The colour of the light (for visible light)
Practise Test Questions
The following information relates to the next 2 questions:
Two soundwaves move through the air. The frequency of sound wave 1 is 220 Hz while the
frequency of sound wave 2 is 22 kHz.
1.
A.
B.
C.
D.
When comparing the two waves:
Sound wave 1 will be moving slower than sound wave 2
Sound wave 2 will be moving slower than sound wave 1
The two sound waves will be moving at the same speed
You cannot tell which is moving faster
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2.
A.
B.
C.
D.
Based on the information above which of the following is most correct.
Both waves could be heard by most humans
Wave 2 has a higher pitch than wave 1
Wave 2 has a higher volume than wave 1
Both have the same frequency
3.
A.
B.
C.
D.
Which of the following types of electromagnetic radiation travels the fastest in air
Radiowaves
Microwaves
Visible light
They all travel at the same speed
4.
A.
B.
C.
D.
As we move from radio waves to gamma rays in the electromagnetic spectrum:
The energy of the wave decreases
The wave length decreases
The frequency of the wave decreases
None of the above
5.
A.
B.
C.
As temperature decreases the speed of a sound wave through the air will:
Decrease because particles move slower when they are cooled
Increase because the particles are closer together
Not change because the sound wave is still moving through air
6.
A.
B.
C.
D.
When visible light travels from air into plastic
The speed of the wave changes
The frequency of the waves changes
The wavelengths of the waves stay the same
The colour of each wave that composes visible light will change
7. Choose the best response from those below. When you turn up the volume on your
ipod you are changing:
A. The frequency of the sound waves and the intensity of the sound
B. The amplitude of the sound waves and the intensity of the sound
C. Pitch of the sound
8. Sonia is listening to a CD in her bedroom when her father storms in and yells “turn
that loud music down”. Sonia looks confused because she doesn’t think it is loud.
The best reason for this is that:
A. Sonia was further away from the music so she didn’t think it was loud
B. Loudness is subjective
C. Sonia’s dad meant to say the pitch was too high but confused it with loudness
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9. If you submerged your head under water and tapped your fingers on the side of the
bath the sound seems much louder than you would expect it to be. The best
explanation for this is that:
A. The wave loses little amplitude as it travels to your ear because it travels efficiently
in water
B. The wave loses more amplitude as it travels to your ear because it travels inefficiently
in water
C. Water is dense and the wave travels quickly through it
D. The wavelengths of sound are longer in water so the sound will be louder
10. As a sound wave travels through the air
A. It will slow down causing the sound to be less intense
B. It will lose energy and its amplitude will decrease causing a fall in volume
C. It will lose energy causing the number of crests to pass a point per unit time to
decrease
D. Its amplitude will increase while its frequency will decrease
11. 1400 hertz is equivalent to ( =1400 / 1000)
A. 140 kHz
B. 14 kHz
C. 1.4 kHz
D. 0.14 kHz
12. Convert 3.5MHz into Hz ( 3.5 x 1 000 000 = 3 500 000 Hz)
A.
B.
C.
D.
350 Hz
0.35 Hz
35 000 Hz
3 500 000 Hz
13. When sound travels through air, the air particles ______.
A. vibrate along the direction of wave propagation
B. vibrate but not in any fixed direction
C. vibrate perpendicular to the direction of wave propagation
D. do not vibrate
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14. Bats detect the obstacles in their path by receiving the reflected
_____________________
A.
B.
C.
D.
infrasonic waves
radio waves
electro-magnetic waves
ultrasonic waves
15. Which of the following statements, about sound waves travelling through a medium,
is not true?
A. 100% of the energy in the sound passes completely through the medium.
B. Sound travels more efficiently through elastic materials.
C. Particles of the medium vibrate but do not change their average positions.
D. Particles of the medium transfer energy to neighbouring particles.
16. The relation between wave velocity 'v', frequency 'f ', and wavelength '' is ______.
3.
1.
2. v=f 
4.
17. The amplitude of a wave is ______.
A.
the distance the wave moves in one second
B.
the distance the wave moves in one time period of the wave
the maximum distance moved by the medium particles on either side of the
C.
mean position
D.
the distance equal to one wave length
18. Sound waves do not travel through:
A. solids
E.
B. liquids
F.
C. gases
G.
D. vacuum
H.
19. Sound waves are:
A. Longitudinal
B. Transverse
C. Partly longitudinal and partly transverse
D. Sometimes longitudinal and sometimes transverse
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20. The frequency which is not audible to the human ear is:
A. 50 Hz
B. 500 Hz
C. 5000 Hz
D. 50000 Hz
wouldn’t expect you to remember this one for test.
21. A sound source sends waves of 400 Hz. It produces waves of wavelength 2.5 m. The
velocity/speed of sound waves is:
V= f x 
V = 400 x 2.5
V=1000 m/s
A. 100 m/s
B. 1000 m/s
C. 10000 m/s
D. 3000 km/s
22. Sound and light waves both:
A. have similar wavelength
B. obey the laws of reflection
C. travel as longitudinal waves
D. travel through vacuum
23. The technique used by bats emitting high frequency sounds to find their way or to
locate food is _______.
A. SONAR
B. RADAR
C. Echolocation
D. Flapping
24. An ultrasonic wave is sent from a ship towards the bottom of the sea. It is found that
the time interval between the sending and receiving of the wave is 1.6 s. What is the depth
of the sea, if the velocity of sound in the seawater is 1400 m/s?
v=d/t (velocity= distance/time) and v=1400 m/s and time to reach the sea floor is half the
time the wave took to get there and back so 1.6/2=0.8 s
Thus
D=v x t
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= 1400 x .8
= 1120m
A. 1120 m
B. 560 m
C. 1400 m
D. 112 m
25. Which of the following is transferred during wave propagation?
A. Speed
B. Mass
C. Matter
D. Energy
26. If a vibrator strikes the water 10 times in one second, then the frequency of the wave is
_________.
A. 10 Hz
B. 0.5 Hz
C. 5 Hz
D. 0.1 Hz
27. Unit of wavelength is __________.
A. newton
B. erg
C. dyne
D. metre
28. The distance between a compression and the next rarefaction of a longitudinal wave is
__________.
A.
B. 2λ

C.
2
D.
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29. Which of the following best describes light and sound waves?
a. Light and sound are both transverse waves
b. Light and sound are both longitudinal waves
c. Light is a transverse wave; sound is a longitudinal wave
d. Light is a longitudinal wave; sound is a transverse wave
30. Sound is:
a. a wave which travels through any material or a vacuum.
b. awave which travels only through air.
c. A wave which travels through many materials but not a vacuum
d. particles which travel through most things.
31. Sound in air can best be described as a:
A. transverse pressure wave of compressions and rarefactions in air.
B. transverse displacement wave which travels through air.
C. transverse polarised pressure wave in air.
D. longitudinal wave of air compressions and rarefactions.
32. The speed of sound in air is closest to:
A 100 m/s
B 300 m/s
C 1000 m/s
D 3 x 108 m/s
33. We set up a loud speaker at the front of the room at ear level. The sound waves that
pass through the room towards you will cause the air molecules in their path to:
A.
B.
C.
D.
vibrate vertically up and down
vibrate horizontally back and forward
vibrate both vertically and horizontally
move toward you in waves
34. The ‘pitch’ of a musical note is normally given in terms of its:
A. amplitude
B. frequency
C. wavelength
D. speed
35. Which of the alternatives (A to D) in the previous question
indicates the loudness of the note? A (note however that loudness is subject
assessment of the sound intensity and amplitude is a measure of the intensity of the sound
wave)
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36. The speed of any periodic wave is given by:
A.
B.
C.
D.
the wavelength times the frequency
the wavelength times the period
the wavelength divided by the frequency
the wavelength divided by the period
37. The normal frequency range of hearing in a young person (who hasn't been to too many
rock concerts) is about: : (wouldn’t be expected to know this)
A 10 Hz to 10 kHz
B 20 Hz to 20 kHz
C 30 Hz to 30 kHz
D 100 Hz to 10,000 Hz
38. The sound level at a rather noisy party (with disco) is most likely to be: (wouldn’t be
expected to know this)
A 40 dB
B 60 dB
C 80 dB
D 100 dB
39. A student directs a beam of light from air into a rectangular Perspex block. Which of the
following diagrams best shows the path of a ray of light from the beam (note no reflected
rays are shown)?
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40. Which of the following is luminous?
A. the sun
B. the moon
C. a flower
D. all of the above
41. A beam of parallel light rays hits a plane mirror. Which statement best describes the
rays after reflection from the surface of the mirror?
A. The rays will converge to a focus
B. The rays will diverge
C. The rays will be reflected at a greater angle than the angle of incidence
D. The rays will be reflected at an equal angle to the angle of incidence
42. The figure shows the path a ray of light takes when travelling from substance 1 into
substance 2. Which letter represents the angle of refraction?
A
C
D
A. A
Substance 2
B
Substance 1
B. B
C. C
D. D
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43. Which of the following diagrams correctly represents a light ray travelling from air into
glass?
A
B
Air
Air
Glass
Glass
C
D
Air
Air
Glass
Glass
44. Which part of the eye focuses light onto the retina?
A. Lens
B. Cornea
C. Aqueous humour
D. Vitreous humour
45. Which part of the eye contains the photoreceptors?
a. Lens
b. Pupil
c. Retina
d. Optic nerve
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Consider the diagram of the eye below.
46. The letter N shows the:
A. The lens
B. The cornea
C. The pupil
D. The iris
47. Which of the following indicates the muscle that adjusts the size of the pupil?
A. M
B. P
C. N
D. O
48 When light passes through a biconvex lens the rays will:
A. converge
B. diverge
C. pass straight through without bending
D. be totally internally reflected.
49. How does the focussing power of a wide convex lens compare to a narrow one?
A. it has great focussing power
B. it a less focussing power
C. the focussing power is not related to the thickness of the lens
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50
The diagram below represents a boy facing a mirror and holding a large letter P.
The image of this letter that the body
sees in the mirror is:
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A.
C.
B.
D.
When looking into the water a coin was seen. It appeared to be floating in the
water. Compared to the image seen the actual coin would be located:
A.
At the same place as the image
B.
Directly below the image
C.
Direction above the image
D.
Below and slightly in front of the image
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