Question

For a current carrying inductor, emf associated is 20mV. Now, current through it changes from 6A to 2A in 2s. The coefficient of mutual inductance is

• A. 20 mH
• B. 10 mH
• C. 1mH
• D. 2 mH

Answer 1

Answer: (B)

10 mH

Answer 2

$\left|e\right| = L \frac{dI}{dt}$
Here, $e = 20 mV = 20 \times10^{-3} V$
$\frac{dI}{dt} = \frac{6-2}{2} = 2 \frac{A}{s }$
$L = ?$
$\Rightarrow 20 \times10^{-3} = L \times 2$
$\therefore \, \, \, L= 10 \times10^{-3} H = 10 \, mH$