Question

Two stationary sources P and Q produce sounds of equal frequency of \(170\,Hz\). The velocity with which an observer has to move from source P towards source Q such that 8 beats are heard per second by the observer is:

• A. \(20\,ms^{-1}\)
• B. \(16\,ms^{-1}\)
• C. \(4\,ms^{-1}\)
• D. \(8\,ms^{-1}\)

Hint:

For two equal-frequency sources and a moving observer: \[ f_b=\frac{2fu}{v}. \] This shortcut is very useful in Doppler beat problems.

Answer 1

The Correct Option is D