CIE A Level Physics

Topic Questions

Syllabus Edition

First teaching 2020

Last exams 2024

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7.1 Waves: Transverse & Longitudinal

11 mark

A wave has a frequency of 4 GHz.

 What is the period of the wave?

  • 25 000 μs

  • 250 ps

  • 25 ns

  • 2.5 ns

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21 mark

A light with wavelength of 600 nm has an orange colour.

 What is the frequency of this light?

  • 500 kHz

  • 500 THz

  • 180 GHz

  • 180 Hz

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31 mark

A sound wave has a frequency of 50 Hz and a speed of 330 m s–1

 If two waves have a phase difference of 60˚, what is the possible distance between two points on the wave?

  • 6.6 m

  • 2.2 m

  • 1.1 m

  • 0.03 m

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41 mark

A sound wave has a displacement y at a distance x from its source at time t.

 Which graph shows correctly the amplitude a and the wavelength λ of the wave ?

cie-ial-physics-images-7-1-e-q4-answer

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51 mark

The following are statements about waves.

1

Longitudinal waves can be polarised.

2

The amplitude of a wave is directly proportional to the energy transferred by the wave.

3

All electromagnetic waves travel at the same speed in a vacuum.

4

The frequency of infra-red light is greater than the frequency of ultra-violet light.

 

Which ones are incorrect?

  • 1, 3 and 4

  • 1, 2 and 4

  • 1, 2 and 3

  • 2, 3 and 4

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61 mark

The vertical cross-section diagram shows a water wave moving from left to right.

cie-ial-images318png

Which points on the diagram show the water moving upwards with maximum speed?

  • 1 and 3

  • 3 only

  • 1 and 4 

  • 4 only

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71 mark

The following statements are about waves. 

1

Waves can travel through free space

2

Waves can be polarised

3

Waves have a frequency inversely proportional to their wavelength

4

Waves have an intensity proportional to their amplitude

 Which ones would apply to both sound and light waves?

  • 3 only

  • 4 only

  • 1 and 4 

  • 1 and 2

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81 mark

The diagram below is a graph showing how the height of water at a point in a marina varies with time t as the waves pass the point.

cie-ial-images320png

What is the correct label for W and X?

 

 

W

X

A

B

C

D

amplitude

displacement

amplitude

displacement

period

wavelength

wavelength

period

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91 mark

Ultraviolet waves have an order of magnitude of the frequency of the longest-wavelength of 10x Hz.

What is the value of x ?

  • 19

  • 17

  • 16

  • 13

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101 mark

Which of the following statements shows that sound waves are longitudinal?

  • sound is diffracted around corners

  • sound is refracted as it passes from hot air to cold air

  • sound cannot be polarised

  • sound can be reflected from a solid surface

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11 mark

The equation below shows the speed of v waves in deep water

                      v squared equals fraction numerator g lambda over denominator 2 straight pi end fraction

 Where g is the acceleration of free fall and λ is the wavelength of the waves. The wavelength λ and the frequency f of the wave were measured. 

If the graph was to give a straight line through the origin which of the following graphs should be plotted?

  • f against λ2

  • f 2 against λ

  • f against  1 over lambda

  • f 2 against  1 over lambda

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21 mark

The graph shows two waves P and Q.

cie-ial-images338png

Wave P has an amplitude of 8 cm and a frequency 100 Hz.

 What is the amplitude and the frequency of wave Q?

 

Amplitude / cm

Frequency / Hz

A

B

C

D

4

4

2

2

300

33

300

33

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31 mark

The graph below shows two sound waves, the sound wave is a series of moving pressure variations.

cie-ial-images339png

Wave 1 has an intensity of 1.6 × 10–6 W m–2, what is the intensity of wave 2 ?

  • 3.6 × 10–6 W m–2

  • 2.4 × 10–6 W m–2

  • 3.0 × 10–6 W m–2

  • 4.5 × 10–6 W m–2

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41 mark

A light wave is incident normally on a surface of area S with an amplitude A. The power per unit area reaching the surface is P.

 If the light is focused on a smaller area of 1 third space s  , and the amplitude of wave is doubled to 2A what is the power per unit area?

  • 6P

  • 12P

  • 18P

  • 36P

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51 mark

All electromagnetic waves travel at speed c in a vacuum with a frequency f and wavelength λ.

 Which row in the table describes the wavelength and speed of electromagnetic waves with a frequency f over 2  ? 

 

Speed in a vacuum

Wavelength

A

2c

2λ

B

c

2λ

C

c

lambda over 2

D

c over 2 lambda over 2

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61 mark

Sound waves can be displayed on a cathode ray oscilloscope (C.R.O.). The graph below represents two waves seen on the screen. They are labelled P and Q as shown in the diagram

cie-ial-images340png

What is the ratio fraction numerator i n t e n s i t y space o f space s o u n d space w a v e space P over denominator i n t e n s i t y space o f space s o u n d space w a v e space Q end fraction  ?

  • fraction numerator square root of 3 over denominator 1 end fraction

  • 9 over 1

  • 1 over 1

  • 3 over 1

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71 mark

The intensity I of a sound at point Q is inversely proportional to the square of the distance x of Q from the source of the sound. This can be shown by the equation

                     I space alpha space 1 over x squared      

cie-ial-images341png            

Molecules of air at Q are a distance r from S and oscillate with amplitude 8.0 μm.

Point T is a distance 2r from S.

 What is the amplitude of oscillation of air molecules at T?

  • 4.0 μm

  • 2.0 μm

  • 2.8 μm

  • 1.4 μm

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81 mark

The graph shows a sinusoidal wave in water, travelling at a speed of 8.0 m s–1

 The maximum speed of the particles in the wave is  where a is the amplitude and f is the frequency.

 cie-ial-images342png

An object Q is floating on the water it has a mass of 2.5 × 10–3 kg

 What is the maximum kinetic energy of Q due to the wave? Assume the motion is vertical.

  • 4.1 mJ

  • 5.1 mJ

  • 39 mJ

  • 64 mJ

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91 mark

A wave has a speed of 340 m s–1 and a frequency of 500 Hz

 If two points on a wave are 0.17 m apart, what is the phase difference?

  • straight pi rad

  • fraction numerator 3 straight pi over denominator 4 end fraction r a d

  • straight pi over 4 space r a d

  • straight pi over 2 space r a d

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101 mark

The sun emits light of a particular wavelength λs. At any instant, there is a range of wavelengths from less than λs to greater than λs­ that can be observed on Earth. This is due to the Doppler effect.

 Which of the following statements would explain this Doppler effect?

  • the Sun is rotating

  • the Sun is moving toward the Earth

  • the Sun is moving away from the Earth

  • the Sun is moving at right-angles to a line joining the Sun and the Earth

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11 mark

Sound travels with a speed of 330 m s–1 in air. The variation with time of the displacement of an air particle due to a sound wave is shown below.

cie-ial-images321png

Which of the following statements about the wave is correct?

  • the wavelength of the sound wave is 1.32 m

  • the graph shows that the sound is a transverse wave

  • the frequency of the wave is 500 Hz

  • the intensity of the wave will be doubled if its amplitude is increased to 0.4 mm

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21 mark

The graph shows two light waves travelling at the same frequency.

cie-ial-images322png

Which of the following could be the phase difference between the two waves?

  • 330˚

  • 260˚

  • 220˚

  • 150˚

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31 mark

The diagram shows a wave moving along a stretched rope in the direction shown.

cie-ial-images324png

Which of the following will be the correct graph to show the variation with time t of the displacement s of the particle Q in the rope ?

cie-ial-physics-images-7-1-m-q3-answer

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41 mark

A wave is travelling through a medium at 24 m s–1 with a frequency of 15 Hz.

What is the phase difference between two points 2 m apart?

  • They are out of phase by half a cycle.

  • There is no phase difference.

  • They are out of phase by a quarter of a cycle.

  • They are out of phase by 0.8 of a cycle.

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51 mark

A plan polarised light of amplitude A is passed through a polarising filter as show in the diagram. The emerging light has an amplitude of A cos theta

 cie-ial-images330png

If the intensity of the beam is I, what is the intensity of the emerging light when θ is 60.0˚?

  • 0.866 I

  • 0.750 I

  • 0.500 I

  • 0.250 I

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61 mark

A police car siren emits a sound wave with a frequency fs of 440 Hz. The car is travelling away from an observer at a speed of 30 m s−1.

 The speed of sound is 340 m s−1.

 Which of the following is the frequency the observer hears?

  • 478 Hz

  • 460 Hz

  • 440 Hz

  • 404 Hz

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71 mark

What is the frequency, amplitude and period of the wave shown in the graph below, to 2 significant figures?

cie-ial-images331png

 

Period / s

Frequency / Hz

Amplitude / m

A

B

C

D

0.0042

0.0035

0.0031

0.0027

240

290

320

290

0.013

0.0065

0.013

0.0065

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81 mark

A sound wave with an amplitude a of 0.2 mm has an intensity of 2.5 W m–2

 If a wave with the same frequency has an amplitude of 2a what is the intensity of the wave?

  • 10.0 W m–2

  • 9.0 W m–2

  • 6.0 W m–2

  • 4.2 W m–2

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91 mark

A sound wave can be displayed on a cathode ray oscilloscope (C.R.O.). The time base is set to 5 μs mm-1.

cie-ial-images332png

What is the frequency of the sound wave?

  • 83 Hz

  • 8.3 Hz

  • 83 kHz

  • 8.3 kHz

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101 mark

The graph shows the displacement of a sound wave over time.

cie-ial-images333png 

When the intensity of the wave is halved, which graph shows the correct displacement of the wave ?

cie-ial-physics-images-7-1-m-q9-answer

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111 mark

A source of sound power P is situated in an open space. The intensity I of sound at distance r from this source is given by

                     I equals fraction numerator P over denominator 4 πr squared end fraction

How does the amplitude A of the vibrating air molecules vary with the distance r from the source ?

  • A space alpha space 1 over r

  • A space alpha space 1 over r squared

  • A space alpha space r

  • A space alpha space r squared

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