# What is the di-electric constant?

Mar 1, 2014

The permittivity of a substance is a characteristic which describes how it affects any electric field set up in it. A high permittivity tends to reduce any electric field present. We can increase the capacitance of a capacitor by increasing the permittivity of the dielectric material.

The permittivity of free space (or a vacuum), ε0, has a value of 8.9 × 10-12 F m-1.

The permittivity of a material is usually given relative to that of free space and it is known as relative permittivity or dielectric constant εr(ω). Thus, the dielectric constant is the property of an electrical insulating material (a dielectric).

Dielectric constant (relative permittivity) εr(ω)

ε(ω): Permittivity

ε0:permittivity of free space (or a vacuum),

The dielectric constant is an expression of the extent to which a material concentrates electric flux. As the dielectric constant increases, the electric flux density increases, if all other factors remain unchanged. This enables objects of a given size, such as sets of metal plates, to hold their electric charge for long periods of time, and/or to hold large quantities of charge. Materials with high dielectric constants are useful in the manufacture of high-value capacitors.