Ohm's Law Lab — 3D Experiment
This is the textbook Ohm's-law experiment rebuilt as a precise 3D laboratory. The switch, rheostat, ideal ammeter and resistor form one series path, while the ideal voltmeter is connected only across the resistor. Each recorded setting adds a matched V–I point to the graph.
How to use this simulation
- Close or open the switch and adjust the rheostat to change the current
- Choose a 10 Ω, 15 Ω or 20 Ω resistor and vary the ideal DC supply
- Record individual meter readings or run the six-setting automatic experiment
- Orbit and zoom the 3D circuit to verify every meter connection
What to look for
- The ammeter sits in series and reads the same current that passes through the resistor
- The voltmeter's blue branch is parallel to the resistor and draws no current
- Every recorded point lies on a straight I–V line through the origin
- V/I remains equal to the chosen resistance at every rheostat setting
- The reciprocal graph slope agrees with the resistor value selected in the laboratory
The physics behind it
With negligible source resistance, an ideal ammeter and an ideal voltmeter, the series current is I = ε/(R + Rₕ). The voltmeter reads only the drop across the resistor under test, V = IR. Holding that resistor at 25 °C keeps R constant, so I is directly proportional to V. Plotting I vertically against V horizontally gives a straight line through the origin whose slope is ΔI/ΔV = 1/R; the reciprocal of the fitted slope therefore returns the resistor's value.