Question

A string of length $36cm$ was in unison with a fork of frequency $256Hz$. It was in unison with another fork when the vibrating length was $48cm$, the tension being unaltered. The frequency of second fork is

• A. $212Hz$
• B. $320Hz$
• C. $384Hz$
• D. $192Hz$

Answer 1

The correct option is D $192Hz$

$f=\frac{v}{2L}$
$v=f\left(2L\right)$
$=256\times 2\times 36$
$=18432cm/s.$

wave velocty remains same
$f=\frac{v}{2L}$
$=\frac{18432}{2\times 48}$
$=192Hz.$