When the switch in a DC circuit is closed, the electrical circuit is closed and the direct electrical current flows through the circuit. The closed switch creates an electrical field within the circuit. The switch also determines the direction in which an electrical current flows.
A switch is used in an electrical circuit to open or close the circuit. A closed switch creates a closed circuit. When a switch is opened, the circuit is opened as well and the flow of the direct electrical current stops as electrons begin to move in random directions throughout the circuit's wire.
In a direct electrical current, electric charge maintains a constant unidirectional flow from areas of high potential to those of low potential. As the circuit begins, the negatively charged electrons accumulate pressure at the negative end of the wire, and as a result, are forced to the opposite, positively charged end of the wire. This pressure is known as potential energy, or voltage. The number of electrons in an electric circuit is the circuit's current, which is measured in amperes. A direct current requires a power source such as a battery or generator to supply the circuit's energy and a conductor such as metal wire.