23.
An observer is moving with half the speed of light towards a stationary microwave source emitting waves at frequency 10 GHz. What is the frequency of the microwave measured by the observer? (speed of light=3×108 ms−1)
A:
10.1GHz
B:
12.1GHz
C:
17.3 GHz
D:
15.3GHz
The answer is:
C