A student wants to use a low-current control circuit to switch a high-current mains appliance on and off safely. Which device should the student use to achieve this?
a diode
a relay
a light-dependent resistor (LDR)
a transformer
136 exam-style questions on CIE IGCSE Physics 4.3 Electric circuits, covering 4.3.1a Circuit diagrams and circuit components, 4.3.2a Series circuits, 4.3.2b Parallel circuits, 4.3.2c Current and potential difference in circuits, 4.3.2d Combined resistance of resistors in parallel, and 4.3.3 Action and use of circuit components. Each one has a worked solution and a mark scheme showing where the marks go.