How are radio waves produced?

Which of the following produces electromagnetic waves?

$A$ parallel plate capacitor is completely immersed in a liquid of resistivity $\rho = 0.25 \, \Omega m$ and relative permittivity $\epsilon_r = 80$. If the plates of the capacitor are connected to an alternating voltage source of $V = V_0 \sin(\omega t)$ at a frequency of $f = 0.4 \, GHz$,then the ratio of the amplitudes of the displacement current $(I_d)$ and conduction current $(I_c)$ is:

Who discovered for the first time that a changing electric field can produce a magnetic field?

$A$ parallel plate capacitor with plate area $A$ and separation between the plates $d$ is charged by a constant current $i$. Consider a plane surface of area $A/2$ parallel to the plates and drawn symmetrically between the plates. The displacement current through this area will be:

If the rate of change in electric flux between the plates of a capacitor is $9 \pi \times 10^3 \text{ Vm s}^{-1}$,then the displacement current inside the capacitor is (in $\mu \text{A}$)