Question

A sonometer wire under a tension of 10 kg weight is in unison with tuning fork of frequency 320 Hz. To make the wire vibrate in unison with a tuning fork of frequency 256 Hz, the tension should be altered by

• A. 3.6 kg decreased
• B. 3.6 kg increased
• C. 6.4 kg decreased
• D. 6.4 kg increased

Answer 1

The correct option is A 3.6 kg decreased

frequency in a sonometer is given as $f=\frac{v}{2l}\sqrt{\frac{T}{\mu }}$

$\frac{f_1}{f_2}=\sqrt{\frac{T_1}{T_2}}$

$\frac{320}{256}=\sqrt{\frac{10\times g}{T_2}}$

$\frac{5}{4}=\sqrt{\frac{10\times g}{T_2}}$

$T_2=\frac{16}{25}\times 10gN$

$T_2=6.4kg$

Tension to be decreased by 3.6 kg.