What do capacitors oppose a change in?

Capacitors are components in electrical circuits that primarily oppose changes in voltage. When a voltage is applied across a capacitor, it stores electrical energy in an electric field. When the voltage changes, the capacitor reacts by either charging or discharging to maintain a stable voltage across its plates. This ability to maintain a constant voltage makes capacitors essential in various applications, such as filtering, timing circuits, and energy storage.

In contrast, while capacitors have effects on current due to their charging and discharging behavior, it is the change in voltage that they fundamentally respond to. The more quickly the voltage changes, the greater the current that flows into or out of the capacitor until it reaches a new steady state. Understanding this voltage opposition is critical for designing circuits that require stable voltage levels during transient conditions.