State Ohm's law ? How can it be verified experimentally ? Does it hold good under all conditions ? Comment.

Explanation

Ohm.s law: At constant temperature, the current flowing through a conductor is directly proportional to the potential difference across its ends. Experiment to verify ohm.s law:
(i) Close the key, so that current begins to flow in the circuit. (ii) Note down the potential difference (V) across the conductor PQ of resistance R shown by the voltmeter and the corresponding current (I) shown by the ammeter.

(iii) Now move the knob of rheostat so that the current in the circuit increases. (iv) Again note down the potential difference (V) across the conductor R in the voltmeter and current in the circuit shown by ammeter. (v) Repeat the experiment five times by increasing the current in the circuit by moving the knob of the rheostat in steps. Plot a graph between V and I by taking V along X- axis along. We get a straight line passing through From orgin

From the graph between V and I, we conclude that I = V, which is Ohm.s law. Hence Ohm.s law is verified experimentally. Ohm.s law does not hold under all conditions. Ohm.s law does not hold for non-ohmic material such as electrolyte.