Electricity can flow round a circuit. A simple circuit has a cell (often called a battery), wires and a component such as a bulb, buzzer or motor. The circuit must be a complete loop with no gaps, joined to both ends of the cell, or the electricity cannot flow and the bulb will not light.
A switch makes a gap in the circuit. When the switch is open, the loop is broken and the bulb goes off. When it is closed, the loop is complete and the bulb lights. Adding more cells makes a bulb brighter; adding more bulbs to the same loop makes each one dimmer. Mains electricity from plugs is very dangerous: never poke anything into a socket.
Worked example
A bulb is joined to a cell with one wire only. Why does it not light?
- Electricity needs a complete loop.
- With one wire there is a gap.
Answer:Add a second wire to close the loop, and it will light.
Key words
- circuit
- a complete loop that electricity flows round
- cell
- stores energy and pushes electricity round a circuit
- switch
- opens or closes a gap in a circuit
- component
- a part of a circuit, like a bulb or buzzer
New questions every time.
NGSS-referenced: 4-PS3-2