Question

A stretched sonometer wire resonates at a frequency of 350 Hz and the next higher frequency of 420 Hz. The fundamental frequency of this wire is

• A. 350 Hz
• B. 5 Hz
• C. 70 Hz
• D. 170 Hz

Answer 1

The correct option is C 70 Hz

Given sonometer vibrates at;

$f_1=\frac{nv}{2L}=350Hz{f}_2=\frac{(n+1)v}{2L}=420Hz$

Now, $f_2-f_1$, we get

$\frac{(n+1)v}{2L}-\frac{nv}{2L}=420-350[\frac{v}{2L}=70Hz]\downarrow$

This is the fundamental frequency

Hence option (C) is correct