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

The device commonly used to store electrical energy in an electric field is a capacitor. A capacitor consists of two conductive plates separated by an insulating material called a dielectric. When voltage is applied across the plates, an electric field forms between them, causing positive charge to accumulate on one plate and negative charge on the other. The amount of energy that a capacitor can store is proportional to the square of the voltage across the plates, as given by the formula ( E = \frac{1}{2}CV^2 ), where ( E ) is the stored energy, ( C ) is the capacitance, and ( V ) is the voltage.

In contrast, resistors are primarily used to limit current and dissipate energy as heat rather than store energy. Inductors store energy in a magnetic field when current flows through them, which is a different principle than that of a capacitor. Transformers are used to change voltage levels in AC circuits through electromagnetic induction and do not store electrical energy. Therefore, the characteristics and function of a capacitor make it the correct choice in this context.