What type of circuit element opposes rates of change of current?

The element that opposes rates of change of current is the inductor. Inductors are components that store energy in a magnetic field created by the flow of current through a coil of wire. When the current through an inductor changes, the inductor generates a counter electromotive force (back EMF) that acts to oppose that change. This behavior is described by Faraday's law of electromagnetic induction, which states that the voltage induced in a coil is proportional to the rate of change of current passing through it.

Inductors are used in various applications, including filtering, energy storage, and in timing circuits, where their ability to resist changes in current can help stabilize the operation. This contrasts with other circuit elements, which serve different purposes. For example, resistors dissipate energy as heat and do not inherently oppose changes in current—they provide a consistent opposition based on their resistance value. Capacitors, on the other hand, oppose changes in voltage, not current. Lastly, voltage sources provide a constant voltage but do not have the characteristics that would cause them to oppose changes in current flow.