parallel-plate capacitor

Question

The plates of a particular parallel-plate capacitor are uncharged. Is the capacitor of this capacitor zero? explain.

Answer 1

No.  The capacitance depends only on the geometry of the capacitor and the properties of the dielectric material between the conductors.  Even if uncharged, it still has capacity to hold charge, which is the true meaning of capacitance.  It is like an empty jar.  The empty jar can still hold water, whether it is filled or not.  Now if you were to apply voltage across the capacitor, then it would charge up in proportion to the applied voltage (q = CV).

 

For a parallel-plate capacitor,

 

C = epsilon * A / d,

 

where A is the area of a plate, d is the separation distance between plates, and epsilon is the electric permitivity of the dielectric material between the plates.