Ohm's Law And Their Limitation

Ohm's law

     "For a fixed metal conductor,the temperature and other conditions remaining constant,the current through it is proportional to the potential difference between it's end".
V ~ I
V = IR
V/I = R
Where R is the resistance

The linear relationship is not applicable for all non-metallic conductor.

Limitations of Ohm's Law

Ohm's law does not apply under the following conditions

1) Electrolytes where enormous gases are produced on either electrode.
2) Non-Linear resistors like vaccum radio valve,gas filled tube,semiconductors.
3) Arc lamp.
4) Metal which get heated up due to flow of current through.
5) Appliances like Metal rectifier,Crystal detector etc. in which operation is depend upon the direction of current.