What is called displacement current?

If the rate of change of electric field across the plates of a parallel plate capacitor is $E$ and the displacement current is $I$,then the area of one plate of the capacitor is ($\varepsilon_{0}$ is permittivity of free space).

Write Maxwell's equations.

The source of a time-varying magnetic field may be:
$(A)$ A permanent magnet
$(B)$ An electric field changing linearly with time
$(C)$ Direct current
$(D)$ A decelerating charged particle
$(E)$ An antenna fed with a digital signal
Choose the correct answer from the options given below:

Imagine a world where free magnetic charges exist. In this world,a circuit is made with a $U$-shape wire and a rod free to slide on it. $A$ current carried by free magnetic charges can flow in the circuit. When the circuit is placed in a uniform electric field $E$ perpendicular to the plane of the circuit and the rod is pulled to the right with a constant speed $v$,the magnetic $emf$ in the circuit and the direction of the corresponding current,arising because of changing electric flux will be ($l$ is the length of the rod and $c$ is the speed of light).

The displacement current through the plates of a parallel plate capacitor of capacitance $30 \mu F$ is $150 \mu A$. The capacitor is charged by a source of varying potential at the rate of: (in $Vs^{-1}$)