A metal wire of linear mass density of `9.8g//m` is stretched with a tension of `10 kg-wt` between two rigid support `1meter` apart. The wire passes at its middle point between the poles of a permanent magnet, and it vibrates in resonance when carrying an alternating current of frequency `n`. the frequency `n` of the alternating source is

Options

A. 50 Hz
B. 100 Hz
C. 200 Hz
D. 25 Hz

Answer

a

Explanation

The wire will vibrate with the same frequency as that
of source. This can be considered as an example of
forced vibration.
`T=10xx9.8 N=98 ` n and `m=9.8 xx 10^(-3)`kg `m^(-1)`
Frequency of wire `f=1/(2L) sqrt((T/m))=1/(2xx1) sqrt((98)/(9.8xx10^(-3)))`
= 50 Hz