Who obtained electromagnetic waves for the first time in the laboratory?

The charge on a parallel plate capacitor varies as $q = q_0 \cos(2\pi \nu t)$. The plates are very large and close together (area $= A$,separation $= d$). Neglecting the edge effects,find the displacement current through the capacitor.

How are radio waves produced?

The voltage between the plates of a parallel plate capacitor of capacity $1 \ \mu F$ is changing at the rate of $4 \ V/s$. The displacement current in the capacitor is: (in $\mu A$)

Give the equation that relates the speed of light $c$,the permeability of free space ${\mu _0}$,and the permittivity of free space ${\epsilon _0}$.

$A$ parallel plate capacitor with plate area $A$ and plate separation $d$ is charged by a constant current $I$. $A$ plane surface of area $A/2$,parallel to the plates,is drawn between the plates. The displacement current through this area is