A light-dependent resistor (LDR) is used in a circuit to control a piece of equipment automatically. What might this circuit be used for?
turning on street lights when it becomes dark.
sounding a warning buzzer when a room becomes too warm.
triggering a security alarm when a pressure pad is stepped on.
switching on a central heating system at a specific time of day.
67 exam-style questions on CIE IGCSE Physics 4.3.3 Action and use of circuit components. Each one has a worked solution and a mark scheme showing where the marks go.