S3.10.2 For the adult
Cells and voltage
Why do some torches use two or three cells?
What this chapter teaches
Voltage is the push that makes a current flow, in volts. Cells joined + to − add their volts, so a bigger push gives a bigger current and a brighter bulb. A cell turned the wrong way cancels one.
Three questions to ask
There is no one right wording. Listen for the idea.
- What is the difference between voltage and current?
- Why does a torch with three cells give a brighter light than one with one cell?
- What happens if one cell in a line is turned the wrong way?
After the chapter, the learner can
- Explain voltage as the push that makes current flow
- Predict how adding cells changes the brightness of a bulb
What they copy into their notebook
Voltage is the push, in volts. Cells in a line add their volts. A bigger push means a bigger current and a brighter bulb. A voltmeter goes across a part.