# Current Density Conductance and Conductivity

## Current Density Conductance and Conductivity:

Current Density (J)- It is defined as the amount of current flowing per unit area of the conductor at a particular point, provided the area is held perpendicular to the direction of the current.

Let ‘I’ be the current distributed uniformly over the cross-sectional area A of the conductor, then

Current density, J is a vector quantity. Its direction is the direction of motion of the positive charge. The S.I. unit of current density if ampere/metre2.

Conductance (G)- The inverse of resistance is called conductance of the conductor i.e.

The S.I. unit of conductance is mho or siemen (S).

Conductivity (σ)- The inverse of resistivity is called the conductivity of the conductor i.e.

The S.I. unit of conductivity is mho-m-1 or siemen-m-1.