Q 12-06-081JEE MainJEE Main 2023 (12 Apr, Shift 1)Easy
A conducting circular loop is placed in a uniform magnetic field of $0.4\ \text{T}$ with its plane perpendicular to the field. Somehow, the radius of the loop starts expanding at a constant rate of $1\ \text{mm s}^{-1}$. The magnitude of induced emf in the loop at an instant when the radius of the loop is $2\ \text{cm}$ will be ______ $\mu$V.
Numerical value type. Enter your answer.
Answer: 50
$\varepsilon=B\cdot2\pi r\dfrac{dr}{dt}=0.4\times2\pi\times0.02\times10^{-3}\approx5.0\times10^{-5}\ \text{V}=50\ \mu\text{V}$.
Solution by Sreeraj P, M.Sc Physics