Ohm’s Law 

The basic law governing the flow of current was discovered by G S Ohm in 1828. Imagine a conductor through which a current I is flowing and let V be the potential difference between the ends of the conductor. 

Then Ohm’s law states that 

V ∝ I

or,     V = R I

where the constant of proportionality R is called the resistance of the conductor. The SI unit of resistance is ohm and is denoted by the symbol Ω. The resistance R not only depends on the material of the conductor but also on the dimensions of the conductor.