The sound of the whistle of an approaching train increases while for a train going away it decreases. This phenomenon is an example of
The phenomenon where the sound of a whistle increases as a train approaches and decreases as it moves away is an example of Doppler effect. It occurs due to the relative motion between the source (train) and the observer (listener), causing a change in the perceived frequency of sound waves.
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The phenomenon where the sound of a whistle of an approaching train increases in pitch while it decreases for a train moving away is known as the Doppler effect. This effect occurs due to the relative motion between the source of sound (the train) and the observer (a person standing on the platform).
As the train approaches, the sound waves are compressed, resulting in a higher frequency and perceived pitch (this is called a blueshift). Conversely, as the train moves away, the sound waves are stretched, causing a lower frequency and perceived pitch (this is called a redshift). The Doppler effect is not only observed with sound but also with electromagnetic waves such as light, which astronomers use to determine the velocities of stars and galaxies.
Understanding the Doppler effect is crucial in various fields, including transportation, meteorology, and astronomy, for interpreting relative motion and velocity based on observed frequency shifts.