Electricity is energy that can make bulbs shine, buzzers buzz and motors spin. To work, it must flow all the way round a loop called a circuit.
Mains and batteries
Mains electricity comes from wall sockets. It is very strong and can badly hurt or even kill you, so always be careful. A battery (or cell) is small and much safer, storing electricity we can carry, like in a torch.
| Mains (wall socket) | Battery / cell |
|---|---|
| Very strong and dangerous | Small and much safer |
| Stays in the wall | You can carry it |
| Powers big things (kettle, telly) | Powers small things (torch, toy) |
Staying safe
Never poke anything into a socket, keep water away from plugs, and never touch pylons or wires on poles. If a plug or wire looks broken, tell a grown-up.
A simple complete circuit
A circuit needs three things joined together: a cell, some wires, and a bulb, so electricity can flow out of one end of the cell, through the bulb, and back into the other.
What makes a bulb light?
When the loop is complete, electricity flows from the cell, through the wires, through the thin metal thread inside the bulb. That thread gets so hot it glows. Break the loop and the glow stops.
Conductors and insulators
Materials that let electricity flow through are conductors — most metals, like copper and steel, which is why wires are made of metal. Materials that do not are insulators: plastic, wood, glass and rubber, used to coat wires safely.
| Conductors (let electricity through) | Insulators (do not) |
|---|---|
| copper, steel, iron, gold | plastic, wood, rubber, glass |
Switches
A switch is a gap you can open and close. On (closed) joins the loop and the bulb lights. Off (open) breaks the loop and the bulb goes dark.