Which device is used to store electrical energy in an electrostatic field?

The correct choice is a capacitor, which is a device specifically designed to store electrical energy in an electrostatic field. When a voltage is applied across the terminals of a capacitor, an electric field is created between the conductive plates, allowing the capacitor to accumulate and hold electrical charge. The amount of charge stored is proportional to the voltage applied and the capacitance value of the capacitor, which is measured in farads.

Capacitors are commonly used in various electronic circuits for functions such as filtering, coupling, and energy storage. Their ability to quickly release stored energy also makes them essential in applications like power supply smoothing and timing circuits.

In contrast, other devices in the list function quite differently. Resistors dissipate electrical energy as heat and are used to limit current flow. Inductors store energy in a magnetic field when current flows through them, while transformers transfer electrical energy between circuits through electromagnetic induction, but they do not store energy.