Boxi Learn › Science › Stage 1 · Observe and Say
Light the bulb: why it needs a loop
SCI-3 Energy changes form but is never made or lostSCI-5 Change one thing, watch one thingX-1 Guess, then check
What many people think
One wire from the battery to the bulb is enough to light it.
The idea
A bulb lights only when there is an unbroken loop from one end of the battery, through the bulb, and back to the other end.
Explain it
A friend says one wire from the battery should light the bulb. Use your finger to trace the path and show them where it stops.
Try at home
With a grown-up, use one 1.5 V battery, a small torch bulb and two wires with bare ends. Light it, then add a gap and test a spoon, foil, a pencil lead and a rubber band. Only small batteries: never wall sockets.