CK-12-Physics - Intermediate

http://www.ck12.org Chapter 16. Electric Potential

FIGURE 16.12

A capacitor with a dielectric.

FIGURE 16.13

The capacitor without a dielectric inserted.

The net effect is that the electric field of the capacitor is reduced along with the voltage across the capacitor, since
V=Ex. By decreasing the voltage, the plates acquire more charge once they are reconnected to the battery. A
dielectric, therefore, increases capacitance. The amount of increase depends upon the material of the insulator.
The dielectric material increases the capacitanceCof the capacitor by a factor ofk, called thedielectric constant
(particular to each dielectric material). The resulting capacitance of the capacitor is then→C=kε 0 Ad. The
permittivity of the material is typically defined asε=kε 0 , wherek>1.