# GCSE Standard Questions: Electric Circuits

Q12. Barry and Cisco investigate the resistance of a wire. They tape a length of wire to a metre ruler and connect it to a resistance meter using crocodile clips.

Take a look at their results.

 Length of wire (cm) Resistance (Ω) Attempt 1 Attempt 2 Attempt 3 Mean 25 8.8 8.3 8.5 8.533 50 16.2 16.1 16.4 16.4 75 23.5 23.8 18.7 23.7 100 30.8 31.1 31.0 31.0

(a)

(i) Describe the pattern shown by these results. Use data in your answer.

[2 marks]

(ii) The students made two mistakes when they recorded their results and completed the table. Identify the mistakes and explain what they should have done.

[2 marks]

(iii) The students have correctly handled an anomaly in their results.

Identify the anomaly and explain how it was correctly handled.

[2 marks]

(iv) The students plan to plot a graph of mean resistance against length. What would you expect a graph of these results to look like?

[2 marks]

(b)

(i) The actual mean resistance values are more than expected. Suggest two possible errors with the experiment.

[2 marks]

(ii) For one of the errors, suggest how the experimental procedure could be improved.

[1 mark]

(Total 11 marks)