A parallel-plate vacuum capacitor has 6.02J of energy stored in it. The separation between the plates is 3.70mm . If the separation is decreased to 1.00 mm,

A) what is the energy now stored if the capacitor was disconnected from the potential source before the separation of the plates was changed?

B)What is the energy now stored if the capacitor remained connected to the potential source while the separation of the plates was changed?

a. 1.63J

b. 22.27J

Explanation:

From the expression used in relating  the capacitance of a capacitor to the area and  distance stated below

from the question, the plates was not changed only the distance was varied. Since distance affect the capacitance, we can conclude that

we can also conclude that the new capacitance will have a value of

a. if the capacitor was disconnected from the potential source before the separation, we can conclude that the charge remain the same

Hence from

earlier

b. if the capacitor remain connected before the separation, the voltage remain constant

Hence