A certain elastic conducting material is stretched into a circular loop. It is placed with its plane perpendicular to a uniform magnetic field B = 0 . 8 T . When released the radius of the loop starts shrinking at a constant rate of 2 cm s – 1 . The induced emf in the loop at an instant when the radius of the loop is 10 cm will be ______ mV .

Step-by-step solution

According to the Faraday's law of electromagnetic induction, the emf induced in a conducting loop is given by, e = - d ϕ d t , here, t is time and ϕ = B A is magnetic flux. Here, e = d ϕ d t = d B A d t = B d π r 2 d t = B π 2 r d r d t = 2 × π × 0 . 1 × 0 . 8 × 2 × 10 - 2 ≈ 10   mV (rounded off)