An observer moves towards a stationary source of sound with a speed `((1)/(5))`th of the speed of sound. The wavelength and frequency of the source emitted are `lamda` and f, respectively. The apparent frequency and wavelength recorded by the observer are, respectively.

Options

A. `1.2f, 1.2lambda`
B. `1.2f, lambda`
C. `f, 1.2lambda`
D. `0.8f, 0.8lambda`

Answer

B

Explanation

Source of stationary `rArr lambda`= constant & `f'=(v+v_s)/v f =(1+v_s/v)f=(1+1/5)f=1.2f`