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?

Options

A. 0.05
B. 0.2
C. Zero
D. 0.005

Answer

B

Explanation

When observer moves towards stationary source then apparent frequency
`n' = [(v + v_(0))/(v)] n = [(v + v//5)/(v)]n = (6)/(5)n = 1.2 n`
Increment in frequency = 0.2n so percentage change in frequency = `(0.2n)/(n) xx100` = 20%