Question

question 7 of 28
how are radar and an approaching siren alike? how are they different?
a. both exhibit the doppler effect, but radar uses radio, and the siren uses sound waves.
b. both use sound waves, but the doppler effect can be observed only with radar.
c. both use sound waves, but the doppler effect can be observed only in the approaching siren.
d. both exhibit the doppler effect, but radar uses sound waves, and the siren uses radio.

Explanation:

The Doppler effect is the change in frequency of a wave in relation to an observer who is moving relative to the wave source. Radar uses radio waves and a siren uses sound waves. Both exhibit the Doppler effect. For example, when a police car with a siren approaches, the frequency of the sound (pitch) seems higher (Doppler effect for sound). Radar (which uses radio waves) also shows the Doppler effect (e.g., in speed - detection, the change in frequency of the reflected radio waves indicates the speed of the object).

Answer:

A. Both exhibit the Doppler effect, but radar uses radio, and the siren uses sound waves.