The fundamental frequency of a sonometer wire is 100 Hz. If a weigth of 3 kg is added to the hanger, the frequency of the wire is doubled. What was the initial load on the hanger ? [ The weight of the hanger is included in the load . ]

Options

A. `0.5` kg wt
B. 2 kg wt
C. 3 kg wt
D. 1 kg wt

Answer

D

Explanation

`n = 1/2 sqrt(T/m) i.e. n propto sqrtT`
` n_(2)/n_(1) = 2/1 = sqrt(T_(2)/T_(1)) :. T_(2) = 4T_(1)`
` :. T_(2) = 4 ` kg. wt. and `T_(1) = 1 ` kg. wt .