1. 14 Worksheet (AS)
Data needed to answer questions can be found in the Data, formulae and relationships sheet.
1 The diagram shows a graph of the displacement of a wave.
Displacement X
Time
What property of the wave is X? [1]
A amplitude
B frequency
C period
D wavelength
2 The graph shows the displacement of particles in a sound wave. Which distance, on the graph,
represents the amplitude of the wave?
[1]
AS and A Level Physics Original material © Cambridge University Press 2010 1

2. 14 Worksheet (AS)
3 Which of the following cannot be polarised? [1]
A infrared waves
B microwaves
C sound waves
D ultraviolet waves
4 Red light has a wavelength of 684 nm. What is its frequency? [1]
2
A 2.05 × 10 Hz
B 4.39 × 105 Hz
C 4.39 × 1014 Hz
D 2.05 × 1020 Hz
5 An oscilloscope is connected to a microphone. The diagram shows the trace displayed when a note
is played.
A note is played of half the amplitude and twice the frequency. The settings of the oscilloscope
remain unchanged. Which diagram shows the trace for this note? [1]
A B
C D
AS and A Level Physics Original material © Cambridge University Press 2010 2

3. 14 Worksheet (AS)
6 Calculate the frequency of the following waves:
a red light of wavelength 6.5 × 10−7 m emitted from a light-emitting diode [2]
b ultrasound of wavelength 7.0 mm emitted by a bat. [2]
7 In a water tank, a dipper oscillating at a frequency of 30 Hz produces surface water waves of
wavelength 2.5 cm.
a Calculate the speed of the water waves. [2]
b Determine the wavelength of the waves when the frequency of the dipper is doubled. [2]
8 The graph shows the displacement of particles in a sound wave.
a Calculate:
i the period of the wave [2]
ii the frequency of the wave. [1]
b On a copy of the diagram draw a wave of the same frequency but four times the intensity. [1]
9 An oscilloscope has its time-base and Y-sensitivity (Y-gain) set on 0.5 ms cm−1 and 0.5 V cm−1,
respectively. A person whistles into a microphone connected to the oscilloscope. The trace
displayed on the oscilloscope screen is shown below.
a Determine the frequency of the sound wave. [2]
b Calculate the wavelength of the sound produced by the whistle. [2]
AS and A Level Physics Original material © Cambridge University Press 2010 3

4. 14 Worksheet (AS)
10 You can use the following equation to determine the intensity of a wave:
power
intensity =
cross - sectional area
This equation can be applied to all waves, including sound.
The intensity of sound at a certain distance from a loudspeaker is 3.5 × 10−3 W m−2.
The amplitude of the sound waves at this point is known to be 0.45 mm. Calculate:
a the power transmitted through a cross-sectional area of 8.0 × 10−5 m2 when the intensity
of sound is 3.5 × 10−3 W m–2 [2]
b the intensity of sound where the amplitude is 0.90 mm [3]
c the amplitude of the sound waves where the intensity is 5.6 × 10−2 W m−2. [3]
11 The intensity of a wave may be defined as the power transmitted per unit cross-sectional area at
right angles to the direction of travel.
a For a point source of light, explain why the intensity I at a distance r away from the source
obeys an inverse square law with distance, that is:
1
I∝ . [3]
r2
b The intensity of visible light from the Sun reaching the upper parts of our atmosphere is
about 1.4 kW m−2. The Sun has a radius of 7.0 × 108 m and is 1.5 × 1011 m from the Earth.
Calculate:
i the intensity of visible light emitted from the Sun’s surface [3]
ii the total power radiated by the Sun in the visible region of the electromagnetic
spectrum [2]
iii the intensity of light from the Sun at the planet Neptune.
(Neptune is 4.5 × 1012 m from the Sun.) [3]
Total: Score: %
40
AS and A Level Physics Original material © Cambridge University Press 2010 4