An observer starts moving with uniform acceleration `a` towards a stationary sound source emitting a whistle of frequency `n`. As the observer approaches source, the apparent frequency, head by the observer varies with time as

Options

A.
B.
C.
D.

Answer

B

Explanation

For observer approaching a stationary source
`n'=(v+v_0)/(v)n` and given `v_0=atimplies n'=((an)/(v))t+n` This is the equation of straight line with positive intercept `n` and positive slope `((n)/(v))`.