A student is given a reel of constantan wire, a metre rule, a battery, a switch, an ammeter, a voltmeter and connecting leads with crocodile clips. The student wants to find out how the resistance of the wire depends on the length of wire used.
Describe a method the student could use. Your answer should include the measurements the student would take and how the results would be used to find the relationship.
The student finds that 60 cm of the wire has a resistance of 3.6 Ω. Calculate the resistance of 25 cm of the same wire.