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More batteries, brighter bulb

Associate the brightness of a lamp or volume of a buzzer with the number and voltage of cells used in a series circuit

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What a learner can do afterwards

  • Describe the pattern: more cells (or higher voltage) = brighter bulb / louder buzzer
  • Explain that more cells provide more energy to the circuit
  • Predict the effect of changing the number of cells on a component's behaviour

The lesson

Every circuit needs energy to make things happen. A battery, or cell, is what pushes that energy around the circuit. Use one cell, and you send one push of energy to the bulb. Add a second cell in a line with the first, and you send two pushes at once.

1 cell12 cells23 cells3
More cells push more energy through the bulb, so it glows brighter.
Try it together

Zara connects one cell to a bulb and it glows softly. She adds a second cell in the same line. The bulb jumps to a much brighter glow, because two cells are now pushing energy into it together.

Good to know

Cells can also be strong or weak. This strength is called voltage. A higher-voltage cell pushes more energy than a lower-voltage one, even if you don't add any extra cells.

Good to know

The same idea works for a buzzer. More cells, or higher-voltage cells, push more energy through the buzzer, so it sounds louder.

More cells, or higher voltage, means more energy pushed through the circuit, so the bulb shines brighter and the buzzer sounds louder.

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.

More batteries, brighter bulb · Science, ages 10 to 11 · LightMySky