Question 21
Question 21 of 40
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No letter options?
Older MCQs might not have the typical A, B, C, D choices. They have choices 1, 2, 3, and a combination of them is the answer. Below is the key that maps such combinations to the answer.
A 1, 2 and 3 are correct
B 1 and 2 only are correct
C 2 and 3 only are correct
D 1 only is correct
Topics Tested
7. Waves
7.1. Progressive waves

understand and use the terms displacement, amplitude, phase difference, period, frequency, wavelength and speed

7. Waves
7.3. Doppler effect for sound waves

understand that when a source of sound waves moves relative to a stationary observer, the observed frequency is different from the source frequency (understanding of the Doppler effect for a stationary source and a moving observer is not required)