An observer moves towards a stationary source of sound with a velocity one-fifth of the velocity of sound. The percentage change in the apparent frequency is

Step-by-step solution

By Doppler's effect ν ' ν = c + ν 0 c (where c is the velocity of sound) ν ' ν = v + v / 5 v = 6 5 ∴ Fractional increase = ν ' - ν ν = ν ' ν - 1 = 6 5 - 1 = 1 5 ∴ Percentage increase = 100 5 = 20   %