Two charged capacitors have their outer plates fixed and inner plates connected by a spring of force constant $k$. The charge on each capacitor is $q$. Find the extension in the spring at equilibrium.

The insulated plates of a charged parallel plate capacitor (with small separation between the plates) are approaching each other due to electrostatic attraction. Assuming no other force to be operative and no radiation taking place,which of the following graphs approximately shows the variation with time $(t)$ of the potential difference $(V)$ between the plates?

Two parallel plate capacitors with different plate separations but the same capacitance are connected in series to a battery. Both capacitors are filled with air. The quantity that is $NOT$ the same for both the capacitors when they are fully charged is:

What is the energy density of a parallel plate capacitor with area $A$ and charge $Q$?

The capacitance of a parallel plate capacitor is $12 \ \mu F$. If the distance between the plates is doubled and the area of the plates is halved,then the new capacitance will be ... $\mu F$.

$A$ parallel plate capacitor has $1\,\mu F$ capacitance. One of its two plates is given $+2\,\mu C$ charge and the other plate,$+4\,\mu C$ charge. The potential difference developed across the capacitor is......$V$