Waves Classwork
1 A sound wave moves with a speed of 320 m s–1 through air. The variation with time of the
displacement of an air particle due to this wave is shown in the graph.
displacement 0.2
/ mm
0
0 2 4 6 8 10 time / ms
–0.2
Which statement about the sound wave is correct?
A The frequency of the wave is 500 Hz.
B The graph shows that sound is a transverse wave.
C The intensity of the wave will be doubled if its amplitude is increased to 0.4 mm.
D The wavelength of the sound wave is 1.28 m.
2 A wave of frequency 15 Hz travels at 24 m s–1 through a medium.
What is the phase difference between two points 2 m apart?
A There is no phase difference.
B They are out of phase by a quarter of a cycle.
C They are out of phase by half a cycle.
D They are out of phase by 0.8 of a cycle.
3 A wave of amplitude a has an intensity of 3.0 Wm –2.
What is the intensity of a wave of the same frequency that has an amplitude 2a?
A 4.2 Wm –2 B 6.0 Wm –2 C 9.0 Wm –2 D 12 Wm –2
4 An electromagnetic wave has a wavelength that is numerically of the same order of magnitude as
the diameter of a nucleus.
In which region of the electromagnetic spectrum does the wave occur?
A gamma ray
B X-ray
C visible light
D infra-red
5 Two light waves of the same frequency are represented by the diagram.
displacement
0
0 100 200 300 400 500 600 phase angle / °
What could be the phase difference between the two waves?
A 150° B 220° C 260° D 330°
6 A sound wave has a speed of 330 m s–1 and a frequency of 50 Hz.
What is a possible distance between two points on the wave that have a phase difference of 60°?
A 0.03 m B 1.1 m C 2.2 m D 6.6 m
7 What is not an essential condition for an observable interference pattern to occur between the
waves from two sources?
A The frequencies of the two sources must be equal.
B The sources must be coherent.
C The sources must emit waves of equal amplitude.
D The waves from the two sources must overlap.
8 A cathode-ray oscilloscope (c.r.o.) is used to display the trace from a sound wave. The time-base
is set at 5 µs mm–1.
1 cm
1 cm
What is the frequency of the sound wave?
A 6.7 Hz B 67 Hz C 6.7 kHz D 67 kHz
9 A wave pulse moves along a stretched rope in the direction shown.
Which diagram correctly shows the variation with time t of the displacement s of the particle P in
the rope?
A B
s s
t t
C D
s s
t t
10 Which statement about electromagnetic radiation is correct?
A Waves of wavelength 5 × 10–9 m are high-energy gamma rays.
B Waves of wavelength 3 × 10–8 m are ultra-violet waves.
C Waves of wavelength 5 × 10–7 m are infra-red waves.
D Waves of wavelength 9 × 10–7 m are light waves.
11 Which statement describes a situation when polarisation could not occur?
A Light waves are reflected.
B Light waves are scattered.
C Microwaves pass through a metal grid.
D Sound waves pass through a metal grid.
12 Which statement about waves is correct?
A All electromagnetic waves travel at the same speed in a vacuum.
B Longitudinal waves can be polarised.
C The amplitude of a wave is directly proportional to the energy transferred by the wave.
D The frequency of infra-red light is greater than the frequency of ultra-violet light.
13 The variation with distance x of the intensity I along a stationary sound wave in air is shown by
the following graph.
0
0 5.0 10.0 15.0
x / cm
The speed of sound in air is 340 m s–1.
What is the frequency of the sound wave?
A 1700 Hz B 2270 Hz C 3400 Hz D 6800 Hz
14 Which statement about longitudinal waves is correct?
A Longitudinal waves include radio waves travelling through air.
B Particles in a longitudinal wave vibrate at right-angles to the direction of transfer of wave
energy.
C Some types of longitudinal wave can be polarised.
D Stationary waves can be produced by the superposition of longitudinal waves.
15 The order of magnitude of the frequency of the longest-wavelength ultraviolet waves can be
expressed as 10x Hz.
What is the value of x?
A 13 B 15 C 17 D 19
16 The speed v of waves in deep water is given by the equation
gλ
v2 =
2π
where λ is the wavelength of the waves and g is the acceleration of free fall.
A student measures the wavelength λ and the frequency f of a number of these waves.
Which graph should he plot to give a straight line through the origin?
A f 2 against λ
B f against λ2
C f against 1
λ
D f 2 against 1
λ
17 What, to two significant figures, are the period, the frequency and the amplitude of the wave
represented by the graph?
10
displacement
/ mm
0 time / ms
0 2 4 6 8 10 12
–10
period frequency amplitude
/s / Hz /m
A 0.0027
.00 370 0.0067
B 0.0031
.00 320 0.013
C 0.0035
.00 290 0.0067
D 0.0042
.00 240 0.013
18 A sound wave consists of a series of moving pressure variations from the normal, constant air
pressure.
The graph shows these pressure variations for two waves at one instant in time.
pressure
variation wave 2
/ 10–2 Pa wave 1
3.0
2.0
1.0
0 distance
0 1.0 2.0 3.0 /m
–1.0
–2.0
–3.0
Wave 1 has an intensity of 1.6 × 10–6 W m–2.
What is the intensity of wave 2?
A 2.4 × 10–6 W m–2
B 3.0 × 10–6 W m–2
C 3.6 × 10–6 W m–2
D 4.5 × 10–6 W m–2
19 The diagram shows a vertical cross-section through a water wave moving from left to right.
At which point is the water moving upwards with maximum speed?
A C
