Q. A magnetic field of $2 \times 10^{- 2}T$ acts at right angles to a coil of area $100\ cm^{2}$ with 50 turns. The average emf induced in the coil is $0.1\ V$, when it is removed from the field in time $T$. The value of $t$ is
A) $0.1\ sec$
B) $0.01\ sec$
C) $1\ sec$
D) $20\ sec$
Explanation
(a) $e = - \frac{N\left( B_{2} - B_{1} \right)A\cos\theta}{\Delta t}$
$\Rightarrow 0.1 = \frac{- 50 \times (0 - 2 \times 10^{- 2}) \times 100 \times 10^{- 4} \times \cos{0{^\circ}}}{t}$
$\Rightarrow t = 0.1\ sec$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.