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

The distance between the plates of a parallel plate capacitor is $4 \ mm$ and the potential difference is $60 \ V$. If the distance between the plates is increased to $12 \ mm$,then:

$A$ parallel plate capacitor was made with two rectangular plates,each with a length of $l=3 \ cm$ and breadth of $b=1 \ cm$. The distance between the plates is $d=3 \ \mu m$. Out of the following,which are the ways to increase the capacitance by a factor of $10$?
$A. l=30 \ cm, b=1 \ cm, d=1 \ \mu m$
$B. l=3 \ cm, b=1 \ cm, d=30 \ \mu m$
$C. l=6 \ cm, b=5 \ cm, d=3 \ \mu m$
$D. l=1 \ cm, b=1 \ cm, d=10 \ \mu m$
$E. l=5 \ cm, b=2 \ cm, d=1 \ \mu m$
Choose the correct answer from the options given below:

Which of the following statements is true when the distance between the plates of a parallel plate capacitor is increased?

The force acting on a charged particle placed between the plates of a charged parallel plate capacitor is $F$. If one plate of the capacitor is removed,then the force acting on the same particle will become:

Does the capacitance of a parallel plate capacitor depend on the potential difference $(V)$ between its plates?