Resistance
Physics: IB Diploma Higher Level, topic 4.7.2
Resistance
Resistance is a measure of how difficult it is for current to flow through a component.
Charge flow
- When charge flows in an electric circuit, the size of the current is affected by two things:
- The resistance: If the resistance is increased, the current will decrease.
- The potential difference: If the potential difference is increased the current will increase.
Units - Ohms
- Resistance is measured in ohms, Ω.
Measuring Resistance
We calculate the resistance using R = Δ V/I. We calculate potential difference using a voltmeter and current using an ammeter at the same time.
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Potential difference across a component
- To measure the resistance of a component (e.g. lamp or resistor), measure the potential difference across the component.
Current through a component
- Use an ammeter to measure the current flowing through a component.
Resistance
- The longer the wire, the higher the resistance.
Test yourself on Resistance
Resistance is a measure of the...
Which variables affect the size of a current?
What would you use to measure the potential difference across a component?
What effect will increasing the current through a filament bulb have on the graph?