Q. The mutual inductance between a primary and secondary circuits is $0.5\ H$. The resistances of the primary and the secondary circuits are $20\ ohms$ and $5\ ohms$ respectively. To generate a current of $0.4\ A$ in the secondary, current in the primary must be changed at the rate of
A) $4.0\ A/s$
B) $16.0\ A/s$
C) $1.6\ A/s$
D) $8.0\ A/s$
Explanation
(a) $e_{2} = M\frac{di_{1}}{dt} \Rightarrow i_{2}R_{2} = M\frac{di_{1}}{dt} \Rightarrow 0.4 \times 5 = 0.5 \times \frac{di_{1}}{dt}$
$\Rightarrow \frac{di_{1}}{dt} = 4\ A/\sec$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.