A long straight solenoid of cross-sectional diameter `d = 5 cm` and with `n = 20` turns per one cm of its length has a round turn of copper wire of cross-sectional area `S = 1.0 mm^(2)` tightly put on its winding. Find the current flowing in the turn if the current in the solenoid winding is increased with a constant velocity `dotI = 100 A//s`. The inductance of the turn is to be neglected.

Explanation

The e.m.f induced in the turn is `mu_(0) n dotI pi (d^(2))/(4)`
The resistance is `(pi d)/(S) rho`.
SO, the current is `(mu_(0) n I S d)/(4 rho) = 2 m A`, where `rho` is the resistivity of copper.