Ohm’s Law

Find a resistance from a V–I graph

Wire the circuit yourself: the ammeter in series with the wire, the voltmeter across it, the rheostat to vary the current and the key to switch it. Then take five settings of the rheostat and read the current and the p.d. off the two meters at each one. Plot V against I and the gradient is the resistance of the wire. Nothing on the bench will tell you what a needle says; that part is yours.