Simple electrical circuits — Science, 7–10 years
Electric current can travel around a complete path. A battery pushes charge through wires and a component, such as a bulb, can use the energy.
A complete path
A simple circuit is a complete loop for electric current. It can include a battery, wires, a switch and a bulb. When the loop is closed, current can travel all the way round and the bulb may light; when there is a gap, it cannot.
Why a circuit is needed
People wanted to make light, sound and movement happen reliably, instead of relying on a spark or a lucky contact. The useful question was how to give electricity a controlled route from a source and back again. The circuit idea solves this and also lets a switch stop or start the flow.
Making one bulb light
Take a 1.5-volt battery, two wires and a small bulb. Touch one wire from the battery's positive end to the bulb's metal tip, and the other from the bulb's metal side to the negative end. The loop is now complete, so current can flow and the bulb lights; remove one wire and it goes out.
The battery does not push through air
A common mistake is to connect both wires to the same end of a battery and expect the bulb to light. It feels reasonable because both wires touch the battery, but they do not make a route through the bulb from one end to the other. The circuit needs two different battery terminals and no gap in the loop.
Circuits in everyday life
A bicycle light, doorbell and torch all use circuits. Pressing a doorbell closes a circuit for a moment, sending current through a part that makes sound. In a home, switches and safety devices control circuits, but mains electricity can be dangerous and must not be tested with homemade connections.
Keep exploring
Other languages
Loading MyLeoNes™…