Circuits need power sources such as batteries. Wires are connected to both the positive and negative ends of the battery (or cell). Circuits contain other electrical components such as bulbs and motors, which allow the electricity to pass through them. Electricity will only flow and travel around a circuit that is complete. They cannot have any gaps or else the electricity cannot pass through and there must be no short circuits.
The basic parts of a circuit include: the battery, the wire(s), the bulb(s), buzzer(s), motor(s) and switches (on and off). When the switch is open, there is a gap in the circuit. This means that the switch is off, and that electricity cannot pass around the circuit. When the switch is closed, the electricity can travel around the circuit as the switch is on. If you add more batteries to a circuit, this will increase the power source (electrical energy) and will make the bulb a lot brighter. The more bulbs you add to a simple circuit, the less the electrical energy, which will make the bulbs a lot dimmer. Motors rotate when electrical energy is flowing around the circuit. Common electrical appliances include: refrigerators, freezers, washing machines, dishwashers, microwaves, ovens, hairdryers, toasters, vacuum cleaners etc.
Take a look at some of our wonderful robins explaining their circuits.