Question

ohm's law is valid only when

Answer 1

Ohm's law is valid only when there is constant temperature..

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Answer 2

In some Conditions Ohm's Law is Valid

Ohm’s law is valid at all temperature unless the temperature changes the state of the matter.But the temperature should be constant when you apply this law.

For eg. you are applying a gradual increase in potential difference across a resistor. By ohm’s law the current through the resistor should have linear relationship with potential difference ie

I= V/R. , I = v *(1/R) , R = resistance is constant so let us take 1/R = a .Now I= a*V ,which is a linear equation.

But if the temperature changes when you are varying the potential, the resistance changes with temperature so now 1/R is not a constant and Current will not have linear relationship with potential. Thus the Ohm’s law breaks.