Simple electric circuits — Physics, 7–10 years
A circuit is a complete path that lets electric current travel and make a device work. Physics, 7–10 years.
A complete path
Electric current can travel around a closed loop. A simple circuit has a power source, wires and a device such as a lamp. If there is a gap anywhere in the loop, current cannot complete its journey and the lamp stays off.
Why the loop matters
Early electrical experiments needed to answer a practical problem: how can a source make a lamp or motor work at a distance? The answer is a complete conducting path. This idea lets us find faults quickly: look for a broken wire, loose connection or empty battery.
Lighting one lamp
Connect the positive end of a 1.5-volt battery to one lamp terminal with a wire. Connect the other lamp terminal to the battery's negative end. The loop is closed, so the lamp lights. Remove one wire: the loop opens and the lamp goes out.
The common mix-up
A battery touching one side of a lamp can look as if it should be enough, especially because batteries have energy. But energy needs a complete route into the lamp and back to the battery. One contact is not a circuit, so the lamp stays off.
Switches and devices
A light switch opens or closes a circuit, so it controls whether current reaches the lamp. Torches, doorbells and many toys use the same basic arrangement. Homes use more complex circuits, so electrical repairs should be done by trained adults.
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