RL-circuits

An RL circuit essentially includes a resistor and an inductor either in series or parallel.

Consider a series RL circuit connected with a constant source of emf and a switch; here, the source is assumed to have zero internal resistance.

When the switch is closed, the current increases in the circuit, which leads to a potential difference across the resistor and inductor.

By applying Kirchhoff's loop rule, the rate of increase of current in the circuit can be determined.

Since the current was initially zero, the initial rate of change of current equals emf over inductance. Hence, the greater the inductance, the slower the current increases.

Over time, as the current increases in the circuit, the rate of current change approaches zero, finally leading to a steady state.

In this state, the final current in the circuit equals emf over resistance and does not depend on inductance. The same current is obtained even if the inductor is removed from the circuit.