How switches work

Recognise that a switch opens and closes a circuit, controlling whether a lamp lights or a buzzer sounds

ages 8 to 98 practice questionsvideo included

What a learner can do afterwards

Explain that a closed switch completes the circuit (current flows) and an open switch breaks it (current stops)
Demonstrate adding a switch to a circuit and using it to control a bulb or buzzer
Relate the switch concept to everyday switches in the home

1 · Read

You already know a bulb only lights up when its circuit is complete. The electricity that moves round that whole loop is called current. A switch is a tiny gap in the wire that you control. Close the gap and the circuit is whole. Open the gap and the circuit breaks.

Close the switch: the gap is filled, current flows, and the bulb lights up.

Open the switch: the gap breaks the loop, so the bulb stays dark.

Try it together

Every wall switch in your home hides this same gap. Flip it up and the circuit closes, so the light turns on. Flip it down and the circuit opens, so the light turns off.

Good to know

You never touch bare wires to turn something on or off. The switch does that job safely, whether it is a lamp, a buzzer, or a doorbell button.

A closed switch completes the circuit and an open switch breaks it. That gap is how switches at home control lamps and buzzers.

2 · Watch

3 · Play

step 1 of 6

Last time you hunted a loop for gaps, because one gap anywhere keeps the bulb dark. The class torch lights now, but the only way to turn it off is to pull a wire off the cell.

Zoe wants a proper on and off. What does a switch add to the torch?

Try it yourself

Open and close the switch, and watch the gap you control do its job.

Take it off screen

Print a worksheetA4 with an answer key page for grown-ups. No screen, no internet.

Where it sits

Learn first

Will the bulb light up?

This opens up

More batteries, brighter bulb

Where this leads

Jobs that lean on this skill. Follow one to see everything it is built on.

Baker Chemist Mechanical Engineer Physicist Car Mechanic Electrical Engineer

Then practise

8 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.

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