Here, VS=0,Vob=18(185)=5ms−1
Frequency, fdirect=(320320−5)640=630Hz
freflected=(320320+5)640=650Hz
Thus, beat frequency, fbeat=650−630=20Hz
An observer is riding on a bicycle and moving towards a hill at 18kmh−1. He hears a sound from a source at some distance behind him directly as well as after its reflection from the hill. If the original frequency of the sound as emitted by source is 640Hz and velocity of the sound in air is 320ms−1, the beat frequency between the two sounds heard by observer will be _____ Hz.
Held on 25 Jul 2022 · Verified 6 Jul 2026.
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Work through every JEE Main Waves & Oscillations PYQ, year by year.