What was used to detect the radio waves?

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

The existence of electromagnetic waves was first predicted by the scientist .......

Which scientist first time produced electromagnetic waves in laboratory?

What suggestion was made to correct the discrepancies in Ampere's circuital law?

$A$ parallel plate capacitor of area $A = 16 \ cm^2$ and separation between the plates $10 \ cm$ is charged by a $DC$ current. Consider a hypothetical plane surface of area $A_0 = 3.2 \ cm^2$ inside the capacitor and parallel to the plates. At an instant,the current through the circuit is $6 \ A$. At the same instant,the displacement current through $A_0$ is . . . . . . $mA$.