AS and A Level Physics Original material © Cambridge University Press 2010 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.

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]

Displacement X

Time

14 Worksheet (AS)

AS and A Level Physics Original material © Cambridge University Press 2010 2

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] A 2.05 × 102 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]

B

D

A

C

14 Worksheet (AS)

AS and A Level Physics Original material © Cambridge University Press 2010 3

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]

14 Worksheet (AS)

AS and A Level Physics Original material © Cambridge University Press 2010 4

10 You can use the following equation to determine the intensity of a wave:

area sectional-crosspowerintensity =

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:

21r

I ∝ . [3]

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: 40

Score: %