Question

A coil of self inductance $2H$ carries a $2A$ current. If direction of current is reversed in $1sec$., then induced emf in it:

• A. $-8V$
• B. $8V$
• C. $-4V$
• D. $Zero$

Answer 1

The correct option is B $8V$

We know that

$E=\frac{ldi}{dt}=0$

Since current of 2 amperer reverses in 2 second

E.M.F. developed is

$E=L\times \frac{2-(-2)}{1}$

$E=2H\times 4A{s}^{-1}$

$E=8v$

Hence (B) is correct answer