Page 201 - Physics Coursebook 2015 (A level)

Chapter 13: Waves
End-of-chapter questions
1 Figure 13.17 shows the screen of an oscilloscope. The time-base of the oscilloscope is set at 500 μs div−1.
Calculate the time period of the signal and hence its frequency. [3]
Figure 13.17 For End-of-chapter Question 1.
2 a
b State one major difference between microwaves and radio waves. [1]
c i Estimate the wavelength in metres of X-rays. [1]
State two main properties of electromagnetic waves. [2] ii Use your answer to i to determine the frequency of the X-rays. [1]
3 A student is sitting on the beach, observing a power boat moving at speed on the sea. The boat has a siren emitting a constant sound of frequency 420 Hz.
The boat moves around in a circular path with a speed of 25 m s−1. The student notices that the pitch of the siren changes with a regular pattern.
a Explain why the pitch of the siren changes, as observed by the student. [1]
b Determine the maximum and minimum frequencies that the student will hear. [4]
c At which point in the boat’s motion will the student hear the most high-pitched note? [1]
(Speed of sound in air = 330 m s−1)
4 Figure 13.18 shows some air particles as a sound wave passes.
P
Figure 13.18 For End-of-chapter Question 4.
a On a copy of the diagram, mark:
i a region of the wave which shows a compression – label it C [1]
ii a region of the wave which shows a rarefaction – label it R. [1]
b Describe how the particle labelled P moves as the wave passes. [2]
c The sound wave has a frequency of 240 Hz. Explain, in terms of the movement of an individual particle,
what this means. [2]
d The wave speed of the sound is 320 m s−1. Calculate the wavelength of the wave. [2]
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