What device is used to store electrical energy in an electric field?

A capacitor is a device utilized for storing electrical energy in an electric field. It consists of two conductive plates separated by an insulating material called a dielectric. When a voltage is applied across the plates, an electric field develops, allowing the capacitor to hold a charge. This property of capacitors makes them essential in various applications, such as filtering signals in electronic circuits, smoothing out fluctuations in power supplies, and even in timing applications.

In contrast, a transformer is designed to transfer electrical energy between two or more circuits through electromagnetic induction, without storing energy. A rectifier serves the purpose of converting alternating current (AC) into direct current (DC), rather than storing energy. A rheostat is a variable resistor that adjusts current flow and can be used to control the brightness of lights or speed of motors, but it does not store electrical energy like a capacitor does.