When a voltage is connected across a wire, an electric field is produced in the wire. Metal wire is a conductorA material which allows charge to move easily through it.. Some electrons around the metal atoms are free to move from atom to atom.
These electrons experience a force which moves them through the wire, causing a movement of charged particles, or current.
Figure caption,
Electrons moving through a wire
Electrical energy is transferred to the electrons each time they pass through the battery.
The battery may be connected to a circuit with components, such as lamps or resistors. When electrons pass through the component, work is done. Some of the energy of the electrons is transferred to the component. This causes a difference in energy across the component, which is known as an electrical potential differenceThe potential difference (or voltage) of a supply is a measure of the energy given to the charge carriers in a circuit. Units = volts (V). This is the voltage between two points that makes an electric current flow between them. (p.d.)