Question

A. The phenomena of apparent change in
frequency of sound heard by the observer due
to relative motion between the source and
observer is called Doppler effect.
Ex: 1) When a whistling train is approaching a
station, for a peroson standing on the
platform, the frequency of sound appear to
increase because the train is in relative
motion with respect to observer​

Answer 1

Answer:

A common example of Doppler shift is the change of pitch heard when a vehicle sounding a horn approaches and recedes from an observer. Compared to the emitted frequency, the received frequency is higher during the approach, identical at the instant of passing by, and lower during the recession.