1. Resistance By the end of this lesson, you will be able to…
Explain how a resistor works.
Describe uses of resistors
Today’s Activities
Concept cartoon – The Long Wire
Practical – effects of using different lengths of wire on current

2. If you have longer wires going to the lamp, it will be brighter.
The length of the wires doesn’t make any difference to the lamp.
If you have shorter wires going to the lamp, it will be brighter.

3. Measuring the current flowing through wires of different lengths.
Length of wire (cm)
Current (A) 10 20 30

4. Resistance
This is where all the components in a circuit oppose the flow of electricity.
Resistor
Wire
Current flow
Longer wires provide more resistance to the flow of current, reducing the brightness of the bulbs in that circuit.

5. Uses of Resistors
Some resistors (including bulb filaments, heating wires, elements in kettles / heaters / geysers / stoves) can heat up to provide useful output energy.
A light bulb such as a torch bulb, contains a resistance wire called a filament which heats up to be white hot when connected in a circuit.