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

Explanation

Here, `m=9.8gm^(-1)=9.8xx10^(-3)kgm^(-1),`
`T=10kgwt=10xx9.8N, l=1m`
`v_(1)=(1)/(2l)sqrt((T)/(m))=(1)/(2xx1)sqrt((10xx9.8)/(9.8xx10^(-3)))=50Hz`