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. Each one has a worked solution and a mark scheme showing where the marks go.