Can you describe an experiment to demonstrate Ohms Law?

Answer 1

You need a d.c. variable-voltage supply, a voltmeter, an ammeter, and a resistive load. The voltmeter must be connected in parallel with the resistive load, and the ammeter in series.

Gradually increase the voltage across the load, in discrete (uniform) steps. For each step, note the values of voltage and corresponding current.

Use your results to plot a graph, with voltage along the horizontal axis, and current along the vertical axis.

If the resulting graph is a straight line, then the load is 'linear' or 'ohmic', and obey's Ohm's Law. If the resulting graph is a curve, then the load is 'non-linear' or 'non-ohmic', and does NOT obey Ohm's Law.

The reciprocal of the slope of the graph, at any point along its length, represents the resistance at that point. For a straight-line graph, the resistance will be constant (obeying Ohm's Law); for a curved-line graph, the resistance will vary along its length (does no obey Ohm's Law).

Remember that Ohm's Law is not a universal law, in other words not all loads obey Ohm's Law - these include metals such as tungsten (used to make the filaments of incandescent lamps), electrolytes, and most solid state devices, such as diodes, etc.