Question

Define current density and write expression for current density in terms of drift velocity

Answer 1

Current density. ... The current density vector is defined as a vector whose magnitude is the electric current per cross-sectional area at a given point in space, its direction being that of the motion of the charges at this point.

Answer 2

According to the theory of electromagnetism, current density is a vector quantity the magnitude of which is equal to the electric current per unit area of cross-section at a particular point in space.

Since it is a vector quantity, it also has a direction which is equal to the motion of the charges at that point.

The expression of current density in terms of drift velocity is given as follows:

I=Anevd

where, I- current density,

A,n and e- constants,

Vd- drift velocity.