What type of electrical component consists of two or more conductive surfaces separated by an insulator?

A capacitor is an electrical component that consists of two or more conductive surfaces, known as plates, which are separated by an insulating material called a dielectric. When a voltage is applied across these plates, an electric field forms, allowing the capacitor to store electrical energy. This ability to store energy relative to the voltage across its plates makes capacitors essential in many electronic circuits, where they are used for filtering, decoupling, energy storage, and timing applications.

Resistors are components that limit the flow of current in a circuit and do not store energy. Potentiometers are variable resistors that can adjust resistance in a circuit but do not contain separate conductive surfaces separated by an insulator. Oscillators generate a repeating waveform and may use capacitors and inductors in their design, but they themselves are not defined as components with conductive surfaces separated by an insulator. Thus, the characteristics of a capacitor make it the correct answer to the question.