A parallel plate capacitor of capacitance $C$ is connected to a battery and is charged to a potential difference $V$. Another capacitor of capacitance $2C$ is similarly charged to a potential difference $2V$. The charging battery is now disconnected and the capacitors are connect in parallel to each other in such a way that the positive terminal of one is connected to the negative terminal of the other. The final energy of the configuration is

A $2\,\mu F$ capacitor is charged to $100$ $volt$ and then its plates are connected by a conducting wire. The heat produced is……..$J$

A body of capacity $4\,\mu \,F$ is charged to $80\,V$ and another body of capacity $6\,\mu \,F$ is charged to $30\,V$. When they are connected the energy lost by $4\,\mu \,F$ capacitor is…….$mJ$

A parallel plate capacitor after charging is kept connected to a battery and the plates are pulled apart with the help of insulating handles. Now which of the following quantities will decrease?

If $E$ is the electric field intensity of an electrostatic field, then the electrostatic energy density is proportional to