Question

Two identical wires are stretched by same tension of $100N$ and each emits a note of frequency $200cycles/sec.$ The tension in one wire is increased by $1N.$ Calculate the number of beats heard per second when the wires are plucked simultaneously.

Answer 1

$t_b=\mid f_1-f_2\mid$
$f=\frac{v}{2l}=\frac{1}{2l}\sqrt{\frac{T}{\mu }};\frac{df}{t}=\frac{1}{2}\frac{dT}{T}$
$df=\frac{1}{2}\frac{dT}{T}\times f=\frac{1}{2}\frac{1}{100}\times 200=1$