Question

An emf of $16V$ is induced in a coil having inductance $4H$, if current in coil is $2A$ (at that moment), then the rate of change of energy stored in solenoid

• A. $30J/s$
• B. $32J/s$
• C. $64J/s$
• D. $8J/s$

Answer 1

The correct option is B $32J/s$

Given, $\epsilon =16V,L=4H$
energy stored in solenoid $\epsilon =\frac{1}{2}L{i}^2$
On differentiate the above equcation,
$\frac{d\epsilon }{dt}=Li\frac{di}{dt}\to \left(\frac{Ldi}{dt}\right)i$
where, $L\frac{di}{dt}=\epsilon$
Hence,
$=16\times 2=32J/s$