Question

Which of the following is correct?
A. Doppler effect in sound and light is asymmetric.
B. Doppler effect in sound and light is symmetric.
C. Doppler effect in sound is asymmetric and in light it is symmetric.
D. Doppler effect in sound is symmetric and in light it is asymmetric.

Answer 1

The Doppler Effect is the shift in wave frequency that occurs when a wave source moves relative to its observer. It was discovered by Christian Johann Doppler, who characterised it as the process of starlight increasing or decreasing as a function of the star's relative velocity.

Complete answer:
The Doppler Effect affects both light and sound. When a sound item approaches you, for example, the frequency of the sound waves rises, resulting in a higher pitch. When it moves away from you, however, the frequency of the sound waves lowers and the pitch falls. The Doppler Effect may be seen in the drop in pitch of ambulance sirens as they pass by, as well as the shift in red light. The Doppler Effect, which was discovered by Edwin Hubble, causes the cosmos to expand. In the disciplines of astronomy and space technology, it is extremely useful.

In physics, the Doppler effect is described as a rise (or reduction) in the frequency of sound, light, or other waves when the source and observer move closer (or further) together. Waves produced by a source are compressed as they move towards an observer. Waves generated by a source travelling away from an observer, on the other hand, extend out.

In sound, the Doppler effect is asymmetric. Even if the relative velocities are the same in both situations, the change in frequency is dependent on whether the source or observer is moving.Since light waves are electromagnetic, the Doppler effect in light is symmetric (do not require medium).

Hence, the correct answer is option C.

Note: The change in pitch perceived as a vehicle with a horn approaches and recedes from an observer is a frequent example of Doppler shift. The received frequency is greater during the approach, identical at the time of passing by, and lower during the recession as compared to the emitted frequency.