Question

The current flowing through the primary coil of mutual inductance 8 H is reduced to zero in ${10}^{-3}$s. As a result of which a $24\times {10}^3$ V is induced in the secondary. The initial current through the primary is _____A.

• A. 2
• B. 1
• C. 4
• D. 3

Answer 1

The correct option is D 3

Given,

$M=8H$

$dI=I_2-I_1=-I_{1}A$

$dt={10}^{-3}s$

$\epsilon =24\times {10}^{3}V$

The induced emf $\epsilon$ in the secondary coil is,

$\epsilon =-M\frac{dI}{dt}$

$24\times {10}^3=\frac{8\times I_1}{{10}^{-3}}$

$I_1=\frac{24}{8}A$

$I_1=3A$