Question

Apparent frequencies of source are $n_1,n_2$ when observer approaches and recedes with a velocity $50m{s}^{-1}$ with respect to the stationary source. Apparent frequencies of the source are $n_3,n_4$ when the same source of sound approaches and recedes with same velocity $50m{s}^{-1}$with respect to stationary observer.

If velocity of sound in air is $350m{s}^{-1}$, the increasing order of apparent frequencies is :

• A. $n_1,n_2,n_3,n_4$
• B. $n_1,n_2,n_4,n_3$
• C. $n_4,n_3,n_2,n_1$
• D. $n_2,n_4,n_1,n_3$

Answer 1

Answer: (D)

$n_2,n_4,n_1,n_3$

$n_1=\left(\frac{V+V_o}{V}\right)n$

$n_2=\left(\frac{V-V_o}{V}\right)n$

$n_3=\left(\frac{V}{V-V_s}\right)n$

$n_4=\left(\frac{V}{V+V_s}\right)n$

$n_2,n_4,n_1,n_3$ are increasing order.