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Relative Dielectric Constant
The factor ε_{0} is the dielectric constant of free space and has a value of 8.854 x 10^{12} farads per m in the rationalized MKS system of units. This is also the capacitance of a meter cube of free space when the field is uniform. The dielectric constant of air and other gaseous dielectrics is slightly higher than that of free space and in nearly all cases this slight difference is neglected. However, the dielectric constant of liquid and solid dielectrics is appreciably greater than that of free space. The ratio of the dielectric constant of a material to that of free space is known as the relative dielectric constant k_{r}. Therefore, Eq. 232 becomes modified to
Typical values of dielectric constants are shown in Table 21.
Liquid and solid dielectrics have higher dielectric constants than free space because of an orientation of electric dipoles, a phenomenon known as dielectric polarization, and explained in Section 222.


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