Question

A tuning fork of frequency 512 Hz is vibrated with a sonometer wire and 6 beats per second are heard. The beat frequency reduces if the tension in the string isslightly increased. The original frequency of vibration of the string is

(a) 506 Hz

(b) 512 Hz

(c) 518 Hz

(d) 524 Hz.

Answer 1

The correct answer is (a) 506 Hz

EXPLANATION: 

The frequency of beats ν = |ν₁-ν₂| = 6 Hz where ν₁ = 512 Hz, ν₂ = frequency of sonometer. Thus ν₂ is either 506 or 518 Hz. 

When the tension in the string is slightly increased the frequency of the sonometer slightly increases. Since the beat frequency reduces it means ν₂<ν₁ so ν₂ is 506 Hz. Option (a).