North Carolina RADAR State Practice Exam

What is the effect of relative velocity on the Doppler shift?

1. The greater the relative velocity, the smaller the frequency shift

2. The greater the relative velocity, the greater the frequency shift

3. Relative velocity has no effect on frequency shift

4. Frequency shift is reversed at high speeds

The correct answer is: The greater the relative velocity, the greater the frequency shift

The correct answer highlights that increased relative velocity between the source of a wave and the observer results in a more significant frequency shift. This phenomenon, known as the Doppler effect, occurs when either the source of waves (such as sound or light) is moving toward or away from the observer. When the source moves closer, the waves compress, causing the frequency to increase and resulting in a higher pitch or blue shift in light. Conversely, when the source moves away, the waves stretch, leading to a decrease in frequency and a lower pitch or red shift in light. The magnitude of this frequency shift is directly proportional to the relative velocity of the source and observer; as this velocity increases, so does the shift. This understanding is crucial as it applies in various fields, including astronomy, radar, and medical imaging, where measuring frequency shifts can provide valuable information about the movement and speed of objects. Low relative velocities would yield smaller shifts, while high velocities would lead to pronounced shifts, thus reinforcing the principle that the greater the relative velocity, the greater the frequency shift.