A mctal wire of linear mass density 9.8 /m is stretched with a tension of 10 kg wt between two rigid supports 1 metre apart. The wire passes at its middle point between the poles of a permanent magnet and it vibreates in resonance when carrying an alternating current of frequency n. the frequency n of alternating source is :

Options

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

Answer

A

Explanation

At resonance `V_(1) = V_(2) `
`rArr n = (1)/(2l) sqrt((T)/(m)) rArr = (1)/(2xx 1) sqrt((10xx 9.8)/(9.8 xx 10^(-3))) `
`rArr n = 50 `Hz
Correct choice is (a)