Ohm’s law states that the current through a conductor between two point is proportional to the potential difference across the points. This principle introduces the constant of proportionality, the resistance, one arrives at the usual mathematical equation that describes this relationship.

I = V/R

Where

I is the current

V is the potential different across the conductor

R is the resistance

Ohm’s law states that the R is this relation with constant independence of the current.

In physics, the term Ohm’s law is also used to refer to various generalizations of the law originally formulated by Ohm.

J = σE

Where

J is the current density

E is the electric field

σ is the conductivity