The main function of a capacitor in a circuit is to store energy and isolate signals. It is an electronic component that can be used to store charge and can store charge between two metal plates. Through the action of an electric field, a capacitor can store charge between two connected objects. A capacitor has two terminals and a dielectric constant, which refers to the relative capacitance capacity of the medium. If the dielectric constant of the medium is larger, then the capacitance of the capacitor will also be larger.