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Edexcel A-Level Physics LDR Resistance

Practise Edexcel A-Level Physics LDR resistance with light intensity, conduction electrons, circuit current and fixed-resistor power.

Syllabus
Pearson Edexcel International Advanced Subsidiary/Advanced Level
Course
Physics XPH11/YPH11
Level
AS

Exam points

  • predict LDR resistance, current and voltmeter changes as incident light intensity varies
  • explain fixed-resistor power changes using LDR electron number, resistance and voltage share

2.4.80 - Illumination effects on LDR resistance question 1

[Maximum number: 4]

Resistors are included in circuits that are used as potential dividers.

The circuit shown below includes a light dependent resistor (LDR). The battery has no internal resistance.

Figure for Question 2.4.80 - Illumination effects on LDR resistance question 1 — Edexcel A-Level Physics AS

As the light intensity incident upon the LDR decreases, the power dissipated in the fixed resistor decreases.

Explain why the power in the fixed resistor decreases. Your answer should include reference to the electrons in the LDR.

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