Q. A coil has an area of $0.05\ m^{2}$ and it has 800 turns. It is placed perpendicularly in a magnetic field of strength $4 \times 10^{- 5}Wb/m^{2}$, it is rotated through $90{^\circ}$ in $0.1\ sec$. The average e.m.f. induced in the coil is
A) $0.056\ V$
B) $0.046\ V$
C) $0.026\ V$
D) $0.016\ V$
Explanation
(d) $e = - \frac{NBA(\cos{\theta_{2} - \cos\theta_{1}})}{\mathrm{\Delta}t}$
$= - \frac{800 \times 4 \times 10^{- 5} \times 0.05\left( \cos{90{^\circ} - \cos{0{^\circ}}} \right)}{0.1} = 0.016\ V$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.