A bus is moving with a velocity of `5 ms^(-1)` towards a huge wall. The drive sounds a horn of frequency 165Hz. If the speed of sound in air is 335 m//s, the number of beats heard per second by a passenger on the bus will be

Options

A. 3
B. 4
C. 6
D. 5

Answer

D

Explanation

As the observer is moving with the source. Apparent frequency of reflected wave
`n' = (v + v_(s))/(v-v_(s)) n = (335 + 5)/(335-5) xx 165 = 170`
`:.` No. of beats `=170-165 = 5`