$A$ parallel plate capacitor of capacitance $20 \; \mu F$ is being charged by a voltage source whose potential is changing at the rate of $3 \; V/s$. The conduction current through the connecting wires, and the displacement current through the plates of the capacitor, would be, respectively:

An electromagnetic wave of frequency $100 \text{ MHz}$ propagates through a medium of conductivity $\sigma = 10 \text{ mho/m}$. The ratio of maximum conducting current density to maximum displacement current density is . . . . . . . $\left[ \text{Take } \frac{1}{4 \pi \epsilon_0} = 9 \times 10^9 \text{ Nm}^2/\text{C}^2 \right]$

An insulator plate is passed between the plates of a capacitor. Then the displacement current

Match List-$I$ with List-$II$ and choose the correct answer from the options given below:
| List-$I$ | List-$II$ |
| :--- | :--- |
| $A$. Gauss's law of magnetostatics | $I$. $\oint \vec{E} \cdot d\vec{a} = \frac{1}{\epsilon_0} \int \rho dV$ |
| $B$. Faraday's law of electromagnetic induction | $II$. $\oint \vec{B} \cdot d\vec{a} = 0$ |
| $C$. Ampere's law | $III$. $\oint \vec{E} \cdot d\vec{l} = -\frac{d}{dt} \int \vec{B} \cdot d\vec{a}$ |
| $D$. Gauss's law of electrostatics | $IV$. $\oint \vec{B} \cdot d\vec{l} = \mu_0 I$ |

The electric field through an area of $2 \ m^2$ varies with time as shown in the graph. The greatest displacement current through the area is at $t = ..... \ \mu s$.

The existence of electromagnetic waves was experimentally confirmed by