Ohm’s law

Procedure

1. Keep the supply off. Identify the resistor and select meter ranges suited to the circuit.
2. Build a series path through the ammeter, rheostat, and resistor. Put the voltmeter across the resistor.
3. Start at a low voltage. Close the switch briefly, note V and I as a pair, then open it.
4. Change the rheostat setting and collect at least five pairs of readings. Keep the resistor from overheating.
5. Plot V against I and draw a best-fit straight line. Use its slope to report R in ohms.

Precautions

1. Work at low voltage with a current limit; build a real circuit under teacher supervision.
2. Keep the ammeter in the series path, never directly across the supply. Open the switch between readings.