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💡 How Switches Work

Flick a switch and the light comes on — but how? Discover how a switch opens and closes the loop in a circuit to turn things on and off.

3
lessons
~15 min
to learn
🔬 Science
subject
Ages 6–12
level
Start the course →

What you’ll learn

  1. Open and Closed CircuitsTell the difference between an open circuit (off) and a closed circuit (on).A closed circuit is a complete loop with no gaps, so electricity flows and the bulb lights up. An open circuit has a gap, so the electricity stops and the bulb goes dark. Closed means on, open means off.
  2. What a Switch DoesUnderstand that a switch opens or closes a gap in a circuit to turn it on and off.A switch is a component that makes or breaks a gap in the loop. When it is open, the circuit is off. When you close it, the loop completes, electricity flows, and the bulb lights up. Switches let us control circuits without touching the wires.
  3. Switches All Around UsRecognise switches in everyday life and explain that they all open and close circuits.Switches come in many shapes — wall switches, buttons, toggles, and remote controls — but they all do the same job. Each one opens and closes a circuit to turn something on or off. A switch puts you in control of the electricity.

Questions this course answers

What is a closed circuit?

A closed circuit is a complete loop with no gaps, so electricity flows and the bulb lights up.

Why does the bulb go dark in an open circuit?

An open circuit has a gap in the loop. Electricity cannot cross the gap, so it stops and the bulb goes dark.

What does a switch do in a circuit?

A switch makes or breaks a gap in the loop, letting you turn the circuit on and off.

When you close a switch, what happens to the bulb?

Closing the switch completes the loop, so electricity flows all the way round and the bulb lights up.

Why are switches useful?

A switch lets you open and close a circuit again and again without unclipping any wires.

What do a wall switch and a doorbell button have in common?

Switches come in many shapes, but they all do the same job: opening and closing a circuit.

Grounded in trusted sources

  • BBC Bitesize
  • Britannica Kids
  • The Physics Classroom
  • Khan Academy

Every Wunder lesson is built from real, reputable sources — never invented.

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