When the potential difference across a component increases from 2.0 V to 8.0 V, the current in it increases from 0.10 A to 0.40 A. What is the resistance of the component?
4.0 Ω4.0\ \Omega4.0 Ω, because the potential difference increased by a factor of four
20 Ω20\ \Omega20 Ω, because the resistance falls as the current in it increases
20 Ω20\ \Omega20 Ω, because the ratio of p.d. to current is the same for both readings
80 Ω80\ \Omega80 Ω, because the two values of resistance must be added together
82 exam-style questions on AQA GCSE Physics 2.1 Current, potential difference and resistance, covering 2.1.1 Standard circuit diagram symbols, 2.1.2 Electrical charge and current, 2.1.3 Current, resistance and potential difference, and 2.1.4 Resistors. Each one has a worked solution and a mark scheme showing where the marks go.