Question

A string of length 1m and mass 2 x 10-5 kg is under tension T. When the string vibrates two successive harmonics are found to occur at frequencies 750 Hz and 1000 Hz. The value of tension is ___ Newton.

Answer 1

The correct answer is 5.
$\frac{V}{2l}=1000-750$
$\frac{V}{2l}= 250$
$V=2\times(1)\times250$
$V=500\,m/s$
$\sqrt{\frac{T}{m}}=500$
$T=(500)^2\,m$
$=500\times500\times2\times10^{-5}=25\times2\times10^{-1}=5N$