Question

The emf induced in the circuit is :

• A. $2\pi a^2{B}_0$
• B. $\pi a^2{B}_0$
• C. $\frac{a^2{B}_0}{2}$
• D. $\frac{\pi a^2{B}_0}{2}$

Answer 1

Answer: (B)

$\pi a^2{B}_0$

Since the flux exists only in the circular region.

the flux through the circuit=$\varphi =B.A=\pi a^2{B}_{0}t(\because B=B_{0}t)$

Thus induced emf=$-\frac{d\varphi }{dt}=-\pi a^2{B}_0$