Two identical electric point dipoles have dipole have dipole moments ${\overrightarrow{\mathrm{p}}}_1=\mathrm{p}\hat{\mathrm{i}}$ and ${\overrightarrow{\mathrm{p}}}_2=-\mathrm{p}\hat{\mathrm{i}}$ and are held on the $\mathrm{x}$-axis at distance '$\mathrm{a}$' from each other. When released, they move along the $\mathrm{x}$-axis with the direction of their dipole moments remaining unchanged. If the mass of each dipole is '$\mathrm{m}$', their speed when they are infinitely far apart is :

Arrangement of charges are shown in the figure. Flux linked with the closed surface $P$ and $Q$ respectively are ________ and ________ .

A parallel plate capacitor having plates of area $S$ and plate separation $d$, has the capacitance $C_1$ in air. When two dielectrics of different relative permittivity $\left({\epsilon }_1=2 \text{and} {\epsilon }_2=4\right)$ are introduced between the two plates as shown in the figure, the capacitance becomes $C_2$. The ratio $\frac{C_2}{C_1}$ is, 

In the figure is shown a system of four capacitors connected across a $10 \mathrm{V}$ battery. The charge that will flow from switch S when it is closed is:

In the figure, a capacitor is filled with dielectrics. The resultant capacitance is

The effective capacity in the following figure between the points $P$ and $Q$ will be