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Energy and voltage in circuits

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Question 8

A student investigates how the resistance of a light-dependent resistor (LDR) varies with light intensity.

a.

Describe the circuit symbol for a light-dependent resistor (LDR).

[1]
b.

The student uses voltmeter and ammeter readings to find the resistance at each light level. One set of readings is shown below.

Light Intensity (lux\text{lux}lux)Voltmeter reading (V\text{V}V)Ammeter reading (mA\text{mA}mA)
1208.41.35

State the equation linking voltage, current, and resistance.

[1]
c.

Show that the resistance of the LDR at 120 lux120\ \text{lux}120 lux is about 6200 Ω6200\ \Omega6200 Ω.

[2]
d.

Another student takes measurements for two more light-sensitive components, X and Y. The graphs show the results.

Graphs of Resistance against Light Intensity for Component X and Component Y

Compare the results for component X and component Y.

[6]

Energy and voltage in circuits Questions

  1. IGCSE
  2. /Physics
  3. /Energy and voltage in circuits