__Ohm’s Law:__

When a certain potential difference or voltage is applied across a conductor, Current will flow through the conductor. The great German scientist **Dr. George Simon Ohm** discovered a definite relationship between applied voltage and current which was considered afterward as **Ohm’s law**.

Let us take the voltage difference or potential difference between the ends of the conductor material be ‘**V**‘ and the current flowing through it be ‘f’ then according to Ohm’s law.

I∝V

or, V/I=constant

This constant is known as the **resistance** of the conductor material and it is denoted by ‘**R**‘.

∴ V/I = R

Ohm’s law holds good where temperature, pressure, and other physical conditions don’t change. It doesn’t hold good for electrolytes are lamps, semiconductors, vacuum tube radio valves, gas-filled tubes, transistors, etc.