Two capacitors $C_1$ and $C_2$ have an equal amount of energy stored in them. What is the ratio of potential differences across their plates?

A parallel plate capacitor has rectangular plates with dimensions $6.0 \mathrm{cm}\times 8.0 \mathrm{cm}$. If the plates are separated by a sheet of Teflon $\left(K=2.1\right)$ $1.5 \mathrm{mm}$ thick, how much energy is stored in the capacitor when it is connected to a $12 \mathrm{V}$ battery?

The capacity and the energy stored in a parallel plate condenser with air between its plates are, respectively, $C_0$ and $W_0$. If the air between the plates is replaced by the glass (dielectric constant$=5$). Find the capacitance of the condenser and the energy stored in it.

A capacitor of capacitance $10 \mu \mathrm{F}$ is connected to battery of emf $20 \mathrm{V}$. Without disconnecting the source a dielectric ($K=4$) is introduced to fill the space between the two plates of the capacitor. Calculate the charge before the dielectric was introduced.

A capacitor of capacitance $10 \mu \mathrm{F}$ is connected to battery of emf $20 \mathrm{V}$. Without disconnecting the source a dielectric ($K=4$) is introduced to fill the space between the two plates of the capacitor. Calculate the charge after the dielectric is introduced.

Find the equivalent capacitance of the combination of capacitors between the points $A$ and $B$ as shown in the figure. Also, calculate the total charge that flows in the circuit when a $100 \mathrm{V}$ battery is connected between the points $A$ and $B$.

Three capacitors each of capacitance $9 \mathrm{pF}$ are connected in series. What is the total capacitance of the combination?