| 单词 | permittivity |
| 释义 | permittivity Symbol 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: F = Q1Q2/r24πε0 In this statement of Coulomb's law using SI units, ε0 is called the absolute permittivity of free space, which is now known as the electric constant . 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: F = Q1Q2/r24πε 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 |
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