What is the purpose of an inductor in an RL circuit?

When current flows through an inductor, a magnetic field is generated around the coil. The strength of this magnetic field is directly proportional to the current passing through the inductor. The key behavior of an inductor is its ability to oppose changes in current. If the current through the inductor is increasing, the inductor generates an induced voltage that acts against the rise in current. Conversely, when the current is decreasing, the inductor generates a voltage that opposes the decrease.

The primary purposes of an inductor in an RL circuit are:

Energy storage: When a voltage is applied across an inductor, it stores energy in its magnetic field. This energy can be later released back into the circuit when the applied voltage changes or when the inductor's magnetic field collapses.

Inductance and reactance: Inductance is the property that quantifies an inductor's ability to store energy in the form of a magnetic field. It is measured in henries (H). Inductors provide a reactance (inductive reactance, XL) to the circuit, which is an opposition to the flow of alternating current (AC). The reactance of an inductor increases with frequency.

Filter and frequency-dependent behavior: In an AC circuit, the inductor's reactance increases with increasing frequency. This characteristic makes inductors useful in filtering out certain frequencies in electronic circuits, allowing them to pass low-frequency signals more easily.

Phase shifting: In an AC circuit, the voltage across an inductor lags behind the current by 90 degrees. This phase difference can be utilized in various applications, such as in phase-shifting circuits and in impedance matching.

Inductors find numerous applications in electronics and electrical engineering, including in power supplies, transformers, chokes, and various filtering and signal conditioning circuits.