Five capacitors, each of capacitance ' $C$ ' are connected as shown in the figure. The ratio of equivalent capacitance between P and R and the equivalent capacitance between P and Q is

The function of a dielectric in a capacitor is

Three capacitors are connected to a battery as shown in figure. The ratio of charge on capacitors $\mathrm{C}_3$ and $\mathrm{C}_1$ is

The capacity of air filled parallel plate capacitor is $\mathrm{C}_0$. One-half of the space between the plates is filled with a dielectric constant ' K ' as shown in figure. The new capacity becomes $\mathrm{C}_{\mathrm{n}}$. The ratio $\mathrm{C}_{\mathrm{n}}$ to $\mathrm{C}_0$ is