Question

An inductor with an inductance of $3.00H$ and a resistance of $7.00\Omega$ is connected to the terminals of a battery with an emf of $12.0V$ and negligible internal resistance. Find the initial rate of increase of current in the circuit.

Answer 1

In the initial stage the inductor will acts like a open circuit and all the voltage drop across the inductor will be equal to the e.m.f of battery

$E=L{\left(\frac{di}{dt}\right)}_0$
${\left(\frac{di}{dt}\right)}_0=\frac{E}{L}=\frac{12}{3}=4A/s$