# GCSE Standard Questions: Electric Circuits

Q8. Marion investigated how the current in a filament lamp varied with the potential difference across the filament lamp.

(a) This shows part of the circuit used:

Complete the circuit by adding an ammeter and a voltmeter. (Use the correct circuit symbols).

[3 marks]

(b) Here is a graph showing some of the results:

Marion then reversed the connections to the power supply and obtained negative values for the current and potential difference.

(i) Draw a line on the graph above to show the relationship between the negative values of current and potential difference.

[2 marks]

(ii) Write down the equation which links current (I), potential difference (V) and resistance (R).

[1 mark]

(iii) Using the data from the graph, determine the resistance of the filament lamp when the potential difference across it is 1.0 V.

[4 marks]

(c) Robin did the same investigation. The ammeter he used had a zero error.

What is meant by a zero error?

[1 mark]

(Total 11 marks)