Q. A coil having 500 turns of square shape each of side 10 cm is placed normal to magnetic field which is increasing at 1 T$s^{- 1}$. The induced emf is
A) 0.1 V
B) 0.5 V
C) 1 V
D) -5 V
Explanation
(d) The magnetic flux through area A placed in magnetic field B is
$\phi = BA\cos\theta$
given, $\theta = 0{^\circ},\ B = 1\ {Ts}^{- 1},$
$\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ A = (10)^{2}{cm}^{2} = 10^{- 2}m^{2}$
$\therefore\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \phi = 1 \times 10^{- 2}$
By Faraday’s law, induced emf is
$\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ e = - N\frac{\mathrm{\Delta}\phi}{\Delta t}$
$\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ = - 500 \times 10^{- 2} = - 5\ V$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.