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

Options

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

Answer

C

Explanation

When observer moves towards stationary source then
f. ` = ((V + U_(0))/(V)) `f
`f ((V + (V)/(5))/(V)) ` f
f. = 1.2 f .
Wavelength is not affected by the motion of observer.
Correct choice is c.