LightMySky

Will the bulb light up?

Identify whether or not a lamp will light in a simple series circuit, based on whether the lamp is part of a complete loop with a battery

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What a learner can do afterwards

  • Predict whether a lamp will light by tracing the circuit for a complete loop
  • Explain that a gap anywhere in the circuit breaks the loop and the bulb won't light
  • Identify the fault in a non-working circuit (e.g. loose wire, missing connection)

The lesson

To know if a bulb will light up, trace the circuit like a path. Start at the cell, follow each wire, and check that the path connects all the way back to the cell. If the path is complete, the bulb lights. If there's a break anywhere, it won't.

cellwirebulbwire
Trace it with your finger: cell, wire, bulb, wire, and back to the cell. Every step connects, so this bulb lights.
cellwiregapwirebulb
This loop has a gap between two wires. Even though the rest connects fine, the bulb will not light.
Try it together

Zara looks at her circuit: a cell, two wires, and a bulb. She traces the loop with her finger, cell to wire to bulb to wire and back to the cell. Every connection touches the next one, so she knows the bulb will light before she even flips it on.

Good to know

A gap doesn't have to be a missing wire. Sometimes a wire looks connected but isn't quite touching. Check every single connection, not just most of them, since one gap anywhere stops the whole loop.

To predict if a bulb lights, trace the whole loop from the cell and back to the cell. One gap anywhere, and it stays off.

Watch it

Where it sits

Where this leads

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

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.

Will the bulb light up? · Science, ages 8 to 9 · LightMySky