What is called displacement current?

$A$ parallel plate capacitor is charged to $60\,\mu C$. Due to a radioactive source,the plate loses charge at the rate of $1.8 \times 10^{-8}\, C/s$. The magnitude of the displacement current is:

$A$ parallel plate capacitor with circular plates of radius $R$ is being charged as shown. At the instant shown,the displacement current in the region between the plates enclosed between $\frac{R}{2}$ and $R$ is given by

$A$ circular parallel plate capacitor of radius $R$ and spacing $d$ is being charged by a constant current $I_D$. Find the magnetic field between the plates at a distance $r$ from the axis,where $r > R$.

$A$ displacement current of $4.0 \text{ A}$ can be set up in the space between two parallel plates of a $6 \text{ }\mu\text{F}$ capacitor. The rate of change of potential difference across the plates of the capacitor is nearly $\alpha \times 10^6 \text{ V/s}$. The value of $\alpha$ is . . . . . . .

$A$ parallel-plate capacitor with circular plates is being discharged. The radius of the circular plates is $10 \ cm$. $A$ circular loop of radius $20 \ cm$ is concentric with the capacitor and located halfway between the plates. If the electric field between the plates is changing at the rate of $3.6 \times 10^{12} \ V/(m \cdot s)$,then the displacement current through the loop is (Assume $\frac{1}{4 \pi \varepsilon_0} = 9 \times 10^9 \ N \cdot m^2/C^2$) (in $A$)