Ohm's law states that the current through a conductor between two points is directly proportional to the potential difference across the two points. Introducing the constant of proportionality, the resistance , one arrives at the usual mathematical equation that describes this relationship:
I = V / R
I is the current through the conductor in units of amperes V is the potential difference measured across the conductor in units of volts R is the resistance of the conductor in units of ohms .
More specifically, Ohm's law states that the R in this relation is constant, independent of the current.