Page 232 - Physics Coursebook 2015 (A level)

Cambridge International AS Level Physics
4 Figure 15.21 shows a standing wave, of frequency 400 Hz, produced by a loudspeaker in a closed tube.
piston
59.0 cm
AB
loudspeaker to signal generator
Figure 15.21 For End-of-chapter Question 4.
a Describe the movement of the air particles at:
iA [2] ii B. [1]
b The piston is slowly moved outwards. The next resonant peak is heard when the length of the column of air is 99.4 cm.
Calculate:
i the speed of the sound [4]
ii the end correction which must be applied when using this tube. [1]
5 a
b A student, experimenting with microwaves, sets up the arrangement shown in Figure 15.22.
Explain what is meant by:
i a coherent source of waves. [2]
ii phase difference. [2]
microwave microwave metal transmitter receiver plate
42.0 cm AB
Figure 15.22 For End-of-chapter Question 5.
With the metal plate at position A there is a very small signal. He slowly moves the plate back, leaving the receiver in the same position. As he does so he finds that the intensity initially rises until it becomes a maximum, then falls back to a minimum. This cycle repeats a total
of five times until the plate reaches position B, where once again there is a minimum.
i Explain why a series of maxima and minima are heard. [2]
ii Calculate the frequency of the microwaves. [5]
c Explain why there was a minimum when the plate was at position A, next to the detector. [2]
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