When a DC current is passed through an inductor, initially, the inductor opposes the change in current flow. According to Faraday’s law of electromagnetic induction, an induced electromotive force (emf) is generated in the inductor that opposes the change in current. This property causes the inductor to resist sudden changes in current, behaving momentarily as if it were an open circuit. As a result, when DC is first applied to an inductor, there is a transient period where the current rises slowly over time as the inductor’s magnetic field builds up.
In a steady-state scenario where DC is continuously applied across an inductor, the inductor allows current to flow through it with minimal opposition once the transient period has passed. The inductor stores energy in its magnetic field as long as current flows through it. The amount of current that flows through the inductor is limited primarily by its resistance (if any) and the voltage applied.
When current passes through an inductor in a DC circuit, the inductor resists sudden changes in current due to its property of self-inductance. This resistance manifests as a voltage drop across the inductor proportional to the rate of change of current (di/dt). In a purely DC circuit with no changes in current, the inductor essentially behaves like a wire with negligible impedance, allowing current to flow unimpeded.
If a DC current is suddenly applied across an inductor, the inductor initially opposes this change by generating a high voltage spike to maintain the continuity of current flow. This phenomenon is characterized by Lenz’s law, which states that the induced voltage opposes the change in current. Over time, this induced voltage diminishes as the inductor’s magnetic field stabilizes, allowing the DC current to flow steadily through the circuit.
In summary, in a DC circuit, an inductor allows current to flow through it once steady-state conditions are reached, while initially resisting changes in current due to its inherent property of self-inductance. Inductors are crucial components in DC circuits for applications such as filtering, energy storage, and controlling the rate of current change.