Electrical Engineering ⇒ Topic : Absolute and Relative Permittivity
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Maninder
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Absolute and Relative Permittivity Permittivity is the property of a medium and affects the magnitude of force between two point charges. The greater the permittivity of a medium, the lesser the force between the charged bodies placed in it and vice-versa. Air or vacuum has a minimum value of permittivity. The absolute (or actual) permittivity ε0 (Greek letter 'epsilon') of air or vacuum is 8.854 x 10-12 F/m. The absolute (or actual) permittivity ε of all other insulating materials is greater than ε0. The ratio ε/ε0 is called the *relative permittivity of the material and is denoted by εr i.e. Obviously, εr for air would be ε0/ε0 = 1. Permittivity of a medium plays an important role in electrostatics. For instance, the relative permittivity of insulating oil is 3. It means that for the same charges (Q1 and Q2) and distance (d), the force between the two charges in insulating oil will be one-third of that in air [See eq. (i)} | |
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