Electromagnetic Waves question bank (Physics)

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

An electromagnetic wave, whose wave normal makes an angle of $45^{\circ}$ with the vertical, travelling in air strikes a horizontal liquid surface. While travelling through the liquid it gets deviated through $15^{\circ}$. What is the speed of the electromagnetic wave in the liquid, if the speed of electromagnetic wave in air is $3 \times 10^8 \mathrm{~m} / \mathrm{s}$ ? $\left(\sin 30^{\circ}=0 \cdot 5, \sin 45^{\circ}=\frac{1}{\sqrt{2}}\right)$