Question

As a train approaches us, the frequency or shrillness of its whistle increases. This phenomenon can be explained by
1. Charles’s Law
2. Faraday’s law
3. Doppler Effect
4. Archimedes Principle

Answer 1

Correct Answer - Option 3 : Doppler Effect

The correct answer is Doppler Effect.

• The Doppler effect is the change in frequency of a wave in relation to an observer who is moving relative to the wave source.

• The phenomenon is named after the Austrian physicist Christian Doppler, who described the phenomenon in 1842.
• A common example of Doppler shift is the change of pitch heard when a vehicle sounding a horn approaches and recedes from an observer.
• We find that as the train approaches us, the frequency (or shrillness) of its whistle increases and when the train goes away from us, then the frequency of its whistle decreases. This happens due to the doppler effect.