08. The Resistance
Jill set up this circuit. She measured the current in the circuit for different pieces of wire. Each wire was the same thickness, and was made of the same kind of metal. The wires were different lengths. She kept the power pack set on the same voltage each time. The table shows her results.
1 a Look at the table of Jill’s results. Which result may be a mistake?
b Explain why you chose this result.
c Calculate the average current for each length of wire. Ignore the incorrect result that you identified in part a.
d Draw a line graph to show Jill’s results. Plot the length of wire on the horizontal axis, and the average current on the vertical axis.
2 Look at the statements below.
a Which one is not a correct conclusion for Jill’s investigation?
b Which of these is the best conclusion? Explain your answer.
A The current is biggest when the wire is shortest.
B The longer the wire, the lower the resistance.
C The shorter the wire, the higher the current.
D The longer the wire, the lower the current. This means that the longer the wire, the higher the resistance.
3 a Which factor or factors did Jill change in her investigation?
b Which factors did she keep the same?
c Was Jill’s test fair? Explain your answer.
4 This graph shows the results of Asif’s investigation.
a What was Asif investigating?
b Which factors should he have kept the same to make his test fair?
c Write a conclusion for Asif’s investigation.
Can you...
> present data as a graph
> draw a conclusion
> explain why a test was fair
