**Current density **at a point in a conductor is defined as the amount of current flowing per unit area of the conductor around that point provided the area is held in a direction normal to the current.

Let I be the current distributed uniformly across a conductor of cross-sectional area A. The magnitude of the current density for all points on that cross-section of the conductor is

J=I/A

Current density is a vector quantity. Its direction is the direction of motion of positive charge. Continue reading “Current Density, Conductance And Electrical Conductivity”