Length of a wire
I can explain why longer wires have a higher resistance than shorter wires.
Length of a wire
I can explain why longer wires have a higher resistance than shorter wires.
Lesson details
Key learning points
- The longer a wire, the greater its resistance.
- Electric current in a wire is a flow of electrons moving through the spaces between ‘atoms’ (metal ions).
- Doubling the length of a wire doubles its resistance.
- Doubling the length of a wire doubles the number of ‘atoms’ (metal ions) in the way of the flow of electrons.
- The resistance of a (uniform) wire is proportional to its length.
Common misconception
Many pupils are likely to still use the terms current, voltage and resistance interchangeably.
Repeatedly question pupils about each term and challenge them to use each one correctly throughout their explanations, both written and verbal.
Keywords
Resistance - Resistance is a measure of how hard it is for current to flow.
Metal ion - A metal ion is formed when a metal atom loses one or more electrons and has a positive charge.
Electron - Electrons are the charges in conductors that flow to give an electric current.
Proportional - Two variables are proportional if one changes as a multiple of the other.
Equipment
Constantan, or nichrome wire, SWG 30-40, metre rules, crocodile clips, electrical leads, ammeters capable of measuring current in milliamps, 3V batteries, wire cutters.
Content guidance
- Risk assessment required - equipment
Supervision
Adult supervision required
Licence
This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).
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