Q. A current passing through a coil of self inductance of 2mH changes at the rate of 20${mAs}^{- 1}$. The emf induced in the coil is
A) $10\ \mu V$
B) $40\ \mu V$
C) $10\ mV$
D) $40\ mV$
Explanation
(d) By Faraday’s second law, induced emf
$e = - \frac{Nd\phi}{dt}\ which\ gives\ e = - L\frac{dI}{dt}$
$\therefore\ \left| e\left| = \right.\ \right.\ 2 \times 10^{- 3} \times 20 \times 10^{- 3}V = 40\mu V$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.