A light-dependent resistor (LDR) and a fixed resistor of resistance 2.0 kΩ2.0\ \text{k}\Omega2.0 kΩ are connected in series with a 6.0 V battery.
A voltmeter is connected across the fixed resistor. The circuit is used to detect changes in light intensity.
The Table shows the resistance of the LDR at three light intensities.
Table
| Light intensity | Resistance of LDR in kΩ\text{k}\OmegakΩ |
|---|---|
| dark | 58 |
| dim | 10 |
| bright | 4.0 |
Describe how the resistance of the LDR depends on the light intensity.
Calculate the current in the circuit when the light is bright.
Calculate the reading on the voltmeter when the light is bright.
The light intensity changes from bright to dark.
Explain what happens to the reading on the voltmeter.
42 exam-style questions on OCR GCSE Physics 3.2 Simple circuits, covering 3.2.1 Series and parallel circuits, 3.2.2 Circuit symbols and circuit diagrams, 3.2.3 Current, potential difference and resistance, 3.2.4 Ohm's law, 3.2.5 Ohmic and non-ohmic resistors, 3.2.6 Designing circuits to investigate resistance, 3.2.7 Linear and non-linear circuit components, 3.2.8 Current-potential difference graphs for components, 3.2.9 Resistance in series and parallel, 3.2.10 Series and parallel circuit problems, 3.2.11 Circuits for measurement and testing, 3.2.12 Power transfer in circuit devices, and 3.2.13 Energy and power in resistor circuits. Each one has a worked solution and a mark scheme showing where the marks go.