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GCSE Standard Questions: Electricity in the Home

Q7. (a) Complete the sentence:

The current through an ohmic conductor is directly proportional to the _ _ _ _ _ _ _ across the component, provided that the _ _ _ _ _ _ _ remains constant.

[2 marks]

(b) The graph shows a 'current – potential difference' graph for a filament lamp.

Explain how the resistance of a filament lamp changes as the potential difference across it increases.

[3 marks]

(c) Many householders are replacing their filament lamps with LED lamps which are more energy efficient. What does more energy efficient mean?

[1 mark]

(d) A Light Dependent Resistor (LDR) is used to turn on an outside lamp when it gets dark.

Part of the circuit is shown below:

 

(i) The light intensity decreases. What happens to the potential difference across the LDR and the current in the LDR?

[2 marks]

(ii) What is the resistance of the LDR when the potential difference across it is 4 V?

Give a reason for your answer.

[2 marks]

(iii) Calculate the current through the LDR when the resistance of the LDR is 5000 Ω. Give your answer to 2 significant figures.

[4 marks]

(Total 14 marks)