Question

In electromagnetic wave, according to Maxwell, changing electric field gives _______.

• A. stationary magnetic field
• B. conduction current
• C. eddy current
• D. displacement current

Answer 1

Answer: (D)

displacement current

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 (free current plus displacement current) over any open surface which has the loop as its boundary.

Thus, it is clearly seen that a changing electric field gives rise to displacement current.