Question 162: Electromagnetic Induction

Question

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 cms$$^{-1}$$. The induced emf in the loop at an instant when the radius of the loop is 10 cm will be __________ mV.

Accepted Answer

$E M F=\frac{d}{d t}\left(B \pi r^{2}ight)$
$=2 \mathrm{~B} \pi \mathrm{r} \frac{\mathrm{dr}}{\mathrm{dt}}=2 	imes \pi 	imes 0.1 	imes 0.8 	imes 2 	imes 10^{-2}$
$=2 \pi 	imes 1.6=\mathbf{1 0 . 0 6}~[$ rounding off $\mathbf{1 0 . 0 6}=\mathbf{1 0}]$

Electromagnetic Induction

Integer / Numeric Answer Type