Push the same voltage through a thin wire and a thick wire and very different currents flow. The wire that lets less through has more resistance, and one tidy ratio captures exactly how much.
Resistance is the ratio of the potential difference across a component to the current through it: R = V divided by I, measured in ohms. A longer wire has more resistance; a thicker wire has less.
Resistance is the ratio of the potential difference across a component to the current through it.
Unit: the ohm. A longer wire has more resistance; a thicker (wider) wire has less.
Change the p.d. across a resistor and watch the current and the resistance ratio.
Four quick checks. Each correct answer earns XP and lights this skill on your star map.
Resistance is defined as...
The unit of resistance is the...
Compared with a short wire of the same material and thickness, a longer wire has...
Compared with a thin wire, a thicker wire of the same length and material has...
Resistance depends on the dimensions of the wire as well as the material.
A potential difference of 12 V drives a current of 0.50 A through a resistor. Find its resistance.
Resistance is voltage divided by current, R = V divided by I, not the other way round. A longer wire has more resistance, and a thicker (wider) wire has less.
Unlocks once the four checks above are done. Worth more XP, written in the style of Paper 2.
A 12 V supply drives 0.50 A through a resistor. Its resistance is...
A current of 2.0 A flows through a 6.0 Ω resistor. The p.d. across it is...
A wire is replaced by one of the same material and thickness but twice the length. Its resistance...
Resistance is mapped. Keep the chain going.