List of top Physics Questions on electrostatic potential and capacitance asked in BHU UET

An $8\, \mu F$ capacitor is connected across $220\,V, 50 \,Hz $ line. What is the peak value of the charge through capacitor?

A parallel plate capacitor having a plate separation on $2\, mm$ is charged by connecting it to a $300\, V$ supply. The energy density is: