A conducting circular loop is placed is a uniform magnetic field B =0.20 T with its plane perpendicular to the field . Somehow, the radius of the loop starts shrinking at a constant rate of `1.0 mm s^(-1)`. Find the induced emf in the loop at an instant when the radius is 2 cm.

Explanation

Let the radius be r at time be r at time t
The flux of the magnetic field at this instant is `Omega = pir^2B`
Thus, `(dOmega)/(dt) = 2pirB(dr)/(dt)`
The induced emf when r= 2
0 cm is, therefore, `varepsilon = 2pi(2cm)(0
02 T) (1
0 mm s^(-1) =2
5 muV`.