A student sets up a circuit to investigate how the speed of a small DC motor varies with voltage.
The DC power supply available to the student only has fixed voltage settings (3 V, 6 V, 9 V, and 12 V).
Describe how the student could modify the circuit by adding a single standard component so they can continuously vary the voltage across the motor.
59 exam-style questions on Edexcel GCSE Physics 10.2 Resistance, covering 10.2.1 Current in a circuit and conservation at junctions, 10.2.2 Resistance and variable resistors, 10.2.3 Series and parallel resistance, 10.2.4 I–V characteristics of components, and 10.2.5 LDRs and thermistors. Each one has a worked solution and a mark scheme showing where the marks go.