# A student is investigating how the resistance of a light dependent resistor (LDR) changes. The student places the LDR in a bright room and then moves it into a dark cupboard. Explain what happens to the resistance of the LDR and how this affects the current in the circuit when the LDR is moved into the dark cupboard, compared to when it was in the bright room.

> OCR A-Level Physics A (H556) — 3.4 Materials · Explain · 5 marks

> An LDR is connected in series with a battery and an ammeter. The LDR is first placed in a brightly lit room, then moved into a dark cupboard.

## Mark scheme (5 marks)

1. The resistance of the LDR increases when moved into the dark cupboard
2. Because the LDR has less light falling on it / lower light intensity
3. The greater resistance makes it harder for current to flow / opposes the flow of charge
4. The current in the circuit decreases
5. Correct linked reasoning — as resistance increases, current decreases because voltage (potential difference) of the battery stays the same / using V = IR logic verbally

## Key terms

- [light dependent resistor (LDR)](https://www.gradenine.co.uk/glossary/light-dependent-resistor-ldr)
- [resistance](https://www.gradenine.co.uk/glossary/resistance)
- [current](https://www.gradenine.co.uk/glossary/current)

## Related

- [Revision notes for OCR A-Level Physics A (H556)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

---
Source: [GradeNine](https://www.gradenine.co.uk/q/a-student-is-investigating-how-the-7659087b) · Published by Druglandscape Ltd.