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

A capacitor is the correct device for storing electrical energy in an electric field. It consists of two conductive plates separated by an insulating material called a dielectric. When voltage is applied across the plates, an electric field develops in the dielectric, resulting in the storage of energy. This energy can be released when needed, making capacitors crucial for various applications such as filtering, signal coupling, and energy storage in power supplies.

In contrast, inductors store energy in a magnetic field when electrical current flows through them. Transformers function to transfer electrical energy between two or more circuits through electromagnetic induction, largely transforming voltage levels, rather than storing energy. Resistors, on the other hand, do not store energy; instead, they dissipate energy as heat in a circuit, serving the purpose of controlling current and voltage levels. Thus, among the options, the capacitor is the only component specifically designed to store energy in an electric field.