A street lamp is switched on automatically when it gets dark. The circuit contains a light-dependent resistor (LDR) joined end to end with a fixed resistor and a switching unit. The switching unit turns the street lamp on when the current in the circuit falls below a set value.
Explain how the circuit switches the street lamp on as it gets dark.
The fixed resistor is replaced by one with a larger resistance. Explain the effect this has on the light level at which the street lamp switches on.
Give one advantage of using an LDR rather than a time switch to control the street lamp.
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.