S3.10.4 For the adult
Resistance
How can I make a bulb dimmer, like the dimmer on a lamp?
What this chapter teaches
Resistance, in ohms, is how much a part slows the current. A longer or thinner wire has more, and pencil lead is graphite with a high resistance. Current equals voltage divided by resistance, and a current through a resistance warms it.
Three questions to ask
There is no one right wording. Listen for the idea.
- Why does a longer piece of pencil lead make a bulb dimmer?
- What happens to the current when the resistance in a loop goes up?
- Why does a thin bulb filament glow while the wires stay cool?
After the chapter, the learner can
- Explain resistance as how much a part slows the current
- Make a dimmer from pencil lead in a circuit
- Explain why wires get warm when current flows
What they copy into their notebook
Resistance is how much a part slows the current, in ohms. Longer or thinner wire has more. Current = voltage ÷ resistance. Current warms a resistance.