Question

An engine whistling at a constant frequency n₀ and moving with a constant velocity goes past a stationary observer. As the engine crosses him, the frequency of the sound heard by him changes by a factor f. The actual differences in the frequencies of the sound heard by him before and after the engine crosses him is

(a) 1/2n₀(1 - f²)

(b) 1/2n₀((1 - f²)/f)

(c) n₀(1 - f/1 + f)

(d) 1/2n₀(1 - f/1 + f)

Answer 1

The correct option  (b) 1/2n₀((1 - f²)/f)