What happens to the voltage across an inductor when the current flowing through it changes?

When the current flowing through an inductor changes, the voltage across the inductor responds in a specific way due to the inductor's property of opposing changes in current. This behavior is rooted in Faraday’s law of electromagnetic induction, which states that a changing magnetic field creates an electromotive force (EMF).

As the current through the inductor starts to change, the inductor generates a voltage that opposes that change. This effect creates a lag in the voltage relative to the current. In other words, the voltage does not respond instantaneously to the change in current; rather, it takes time for the voltage to adjust according to the rate of change of the current. This relationship illustrates the inductive reactance present in the circuit, demonstrating that inductors do not permit sudden changes in current and thus create a phase difference between current and voltage.

This characteristic is vital in many applications, including filtering and energy storage in power supplies, where managing the timing of current flow is crucial for the overall performance of an electronic system.