A ring of radius 0.1m is made out of thin metallic wire of area of cross section `10^(-6)m^(2)`. The ring has a uniform charge of `pi` coulombs. Find the change in the radius of the rig when a charge of `10^(-8)C` is placed at the center of the ring. Young's modulus of the metal is `2xx10^(11)Nm^(-2)`.

Explanation

Wthe the magnetic field is swiched the tension increase . The lenth of wire .
` Y = (T/A) //(Deltal/L)`
` or AL = (TI)/(TA)= (iaB) //(Ypi r^(2)`
`2 pi xx Delta r = (iaB 2pi a )//(Y pi r^2 ) ` .