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

A $5\, \mu F$ capacitor is charged fully by a $220\,V$ supply. It is then disconnected from the supply and is connected in series to another uncharged $2.5\;\mu F$ capacitor. If the energy change during the charge redistribution is $\frac{ X }{100} \;J$ then value of $X$ to the nearest integer is$.....$

The insulated spheres of radii ${R_1}$ and ${R_2}$ having charges ${Q_1}$and ${Q_2}$ respectively are connected to each other. There is

A capacitor of capacitance $C$ is charged to potential difference $V_0$. Now this capacitor is connected to an ideal inductor. When $25\%$ of energy of capacitor is transferred to inductor then at that time what will be potential difference across capacitor

A parallel plate capacitor is charged to a certain potential and the charging battery is then disconnected. Now, if the plates of the capacitor are moved apart then:

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 connected to another battery and is charged to potential difference $2V$. The charging batteries are now disconnected and the capacitors are connected 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