Question

Write an expression for the displacement current.

Answer 1

By integral form of modified Maxwell's equations, we have:

${\oint }_{\partial S}B\cdot d\ell ={\mu }_0{\int }_S(J+{ϵ}_0\frac{\partial E}{\partial t})\cdot dS$

Where the displacement current density is given by:

$J_D={ϵ}_0\frac{\partial E}{\partial t}$

The above integral states that, the line integral of magnetic field around any loop is equal to ${\mu }_0$ times the surface integral of the total current density.