Let `vv_s` be the speed of the source emitting waves, n the actual frequency of the source of sound, v the speed of the sound in the medium and n' the frequency of sound waves as percevied by a stationary observer to whom the source of sound is approaching. The formula to calculate for n' is

Options

A. `n'=n(1-vv_s/vv)`
B. `n'=n//(1-vv_s/vv)`
C. `n'=n//(1+vv_s/vv)`
D. `n'=n`

Answer

B

Explanation

When source approaches observer, the apparent frequency,`n'=(V/(V-V_(s)))xxn`
`n'=n/(((V-V_(s)))/V)`
`n'=n/((1-V_(s)/V))`