Limitations of ohm's law
Dear Student,
1.Ohm's law is valid for conductors only at a constant temperature. The resistance of a conductor increases with temperature. Therefore, for changing temperature the V-I graph for a conductor will be non-linear.
2.In case of insulators ohm's law is not followed at all because insulators do not conduct at all.
3.Ohm's law is not followed by semiconductors. The V-I graph has a steep rising at a particular voltage, which indicates that the material begins to conduct properly only after a certain voltage.
Regards