Physics (AS & A Level) · May / June 2026 · Paper 14 · Question 34

A variable resistor and a light-dependent resistor (LDR) are connected in series. The resistance R of the variable resistor is adjusted so that, when light falls on the LDR, the combined resistance of the two resistors remains the same. Which graph could represent the variation of R with the intensity of light that is incident on the LDR?

1. AGraph A: R increases with light intensity (curve rising from origin)
2. BGraph B: R decreases with light intensity (curve falling)
3. CGraph C: R decreases linearly with light intensity
4. DGraph D: R constant with light intensity

As printed in the paper