Question

An observer moves towards a stationary source of sound, with a velocity one-fifth of the velocity of sound. What is the percentage increase in the apparent frequency?
A. `5%`
B. `20%`
C. zero
D. `0.5%`

Answer 1

Correct Answer - B
`f=f_0((v_S+v_O)/(v_S))=f_0[(v+(v)/(5))/(v)]=(6)/(5)f_0`
Percentage increases
`=[((6)/(5)f_0-f_0)/(f_0)]xx100=20%`