Unit 1 · What's going on? 5 minAge 8+
A complete loop
Electrons need a path back home. That's a circuit.
Read first: Resistance
A circuit is a loop. Electrons leave the battery from the negative side, travel through your wires and parts, and come back to the positive side. If the loop is broken anywhere, nothing works.
When the loop is closed, electrons can flow and the LED lights up. When it's open — say, a switch is off, or a wire fell out — the electrons have nowhere to go and everything stops.
Why does the LED stop glowing when you turn the switch off?
Now you understand…
- A circuit is a closed loop.
- Open the loop anywhere → nothing works.
- A loop with no parts in it is a short — never do that on purpose.
Now meet the parts that live inside your loop, one at a time.