A technician tests a fixed resistor in a model railway controller. The potential difference across the resistor is 4.0 V and the current through it is 0.20 A.
A 30 Ω resistor is then connected in series with the fixed resistor, and the potential difference across the combination is set to 12 V.
Both resistors stay at constant temperature.
Calculate the current through the combination.
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.