School › Electricity › Ages 10–11
Circuits, conductors and insulators
What current is, why circuits must be complete, conductors and insulators, series and parallel circuits, and safety. With a conductor-tester experiment.
Read
An electric current is a flow of electric charge. In metal wires the charge is carried by tiny particles called electrons. A battery gives the energy that pushes the current round the circuit.[1]
Current only flows when there is a complete loop, a closed circuit, from the battery through the components and back. A switch breaks or completes the loop.[2]
Materials that let electricity flow easily are conductors: metals such as copper, because they contain electrons that can move freely. Materials that do not let it flow are insulators: glass, rubber and plastic. That is why electric cables are copper wire inside a plastic or rubber coat.[5]
In a series circuit the components are in one single loop, and the same current goes through each of them. In a parallel circuit each component has its own branch and gets the full voltage of the battery. Houses are wired in parallel, so each lamp or appliance can be switched on and off on its own.[3]
Mains electricity is much stronger than a battery and is dangerous. Never poke anything into sockets or appliances, keep appliances away from water, never touch them with wet hands, keep out of substations and never fly kites near overhead lines.[6]
Try it: Conductor or insulator?
You need
- A 3 V battery pack (2 × AA) in a holder
- A small bulb (or LED) in a holder
- Three wires with crocodile clips
- Test objects: steel spoon, aluminium foil, coin, wooden lolly stick, plastic ruler, rubber band, paper, glass marble, string
Safety
Use batteries only, never mains. If a wire or battery gets hot, disconnect it. Do not put the clips straight onto each other for long (that is a short circuit).
What to do
- Build a circuit: battery, bulb and wires, but leave a gap between two crocodile clips.
- Touch the two clips together: the bulb should light. This checks your circuit works.
- Predict for each object: will the bulb light? Write it down.
- Clip each object into the gap, one at a time. Does the bulb light?
- Sort your objects into conductors and insulators. What do the conductors have in common?
Play: Conductor or insulator?
Does it let electricity flow? Sort each material.
Your best score is kept only on this device. Nothing is sent anywhere.
Quiz
Other ages: Ages 6–7 · Ages 15–16