 |
|
| A B C D E F G H I J K L M N O P Q R S T U V W X Y Z |
| • HOME • ABOUT • CATEGORIES • USE OF TEXT AND IMAGES • NEWSLETTER   
|
permittivity (ε)
The ratio of the electric displacement in a medium to the intensity of the electric field producing it. It is important for electrical insulators used as dielectrics.
If two charges q1 and q2 are separated by a distance r in a vacuum, the force F between the charges is given by:
In this statement of Coulomb's law using SI units, ε0 is called the electric constant, or, in older terminology, the absolute permittivity of free space. It has the value 8.854 × 10-12 F m-1.
If the medium between the charges is anything other than a vacuum the equation becomes
and the force between the charges is reduced. ε is the absolute permittivity of the new medium. The relative permittivity (εr ) of a medium, formerly called the dielectric constant, is given by εr = ε / ε0.
Related category
• ELECTRICITY AND MAGNETISMAlso on this site:
Encyclopedia of Alternative Energy & Sustainable Living
Encyclopedia of History