According to Maxwell,when do charges emit electromagnetic waves?

If $\varepsilon_0$ denotes the permittivity of free space and $\phi_{E}$ is the flux of the electric field through the area bounded by the closed surface,then the dimensions of $\left(\varepsilon_0 \frac{d \phi_{E}}{dt}\right)$ are that of

The source of displacement current is . . . . . . .

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 $\mu \text{A}$)

What is the phase difference between the space current and the capacitive displacement current produced when radio waves pass through the ionosphere?

Which scientist first time produced electromagnetic waves in laboratory?