Aparallel-plate air capacitor is made from two plates 0.210 m square, spaced 0.815 cm apart. it is connected to a 120 v battery. if the plates are pulled apart to a separation of 1.63 cm , suppose the battery remains connected while the plates are pulled apart. part a what is the capacitance?

at the beginning:

when the plates are pulled apart:

Explanation:

The capacitance of a parallel-plate capacitor is given by

where

k is the relative permittivity of the medium (for air, k=1, so we can omit it)

is the permittivity of free space

A is the area of the plates of the capacitor

d is the separation between the plates

In this problem, we have:

is the area of the plates

is the separation between the plates at the beginning

Substituting into the formula, we find

Later, the plates are pulled apart to , so the capacitance becomes

option number c is the right answer.

answera compound;