A stretchable conducting ring is in the shape of a circle. It is kept in a uniform magnetic field (B) that is perpendicular to the plane of the ring. The ring is pulled out uniformly from all sides so as to increase its radius at a constant rate `(dr)/(dt) = V` while maintaining its circular shape. Calculate the rate of work done by the external agent against the magnetic force when the radius of the ring is `r_(0)`. Resistance of the ring remains constant at R.

A stretchable conducting ring is in the shape of a circle. It is kept

1.	A stretchable conducting ring is in the shape of a circle. It is kept in a uniform magnetic field (B) that is perpendicular to the plane of the ring. The ring is pulled out uniformly from all sides so as to increase its radius at a constant rate `(dr)/(dt) = V` while maintaining its circular shape. Calculate the rate of work done by the external agent against the magnetic force when the radius of the ring is `r_(0)`. Resistance of the ring remains constant at R.
Answer» Correct Answer - `(4pi^(2)B^(2)r^(2)v^(2))/(R)`

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