Resistance
Applied Science: BTEC Level 3 National Extended Diploma, topic 3.7.3
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 = V/I. We calculate potential difference using a voltmeter and current using an ammeter at the same time.
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 potential difference across a component?
What effect will increasing the current through a filament bulb have on the graph?