A parallel plate capacitor with capacitance C is charged to a potential V. It is then disconnected from the battery and the distance between the plates is doubled. What happens to the energy stored in the capacitor?

An electric dipole is placed at an angle of $30^\circ$ with an electric field of intensity $2 imes {10^5}N/C.$ It experiences a torque equal to 4 Nm. Calculate the charge on the dipole if the dipole length is 2 cm:-