Mains electricity and alternating current

• Electricity can flow either as direct or alternating current, and is used in homes to power electrical appliances.
• The National Grid distributes electricity throughout the country.
• An electric current is the movement of electrically charged particles, for example, electrons moving through a wire or ions moving through a solution.
• A direct current flows in only one direction.
• On a voltage-time graph, a direct current would appear as a straight horizontal line at a constant voltage.
• Car batteries, dry cells and solar cells all provide a direct current (dc) that only flows in one direction.
• An alternating current regularly changes direction.
• On a voltage-time graph, an alternating current would appear as a curve alternating between positive and negative voltages.
• The positive and negative values indicate the direction of current flow.