The property of the material that measures the resistance offered to the formed electric field or an ongoing electric field is known as permittivity. It is represented by the Greek letter epsilon, ϵ. It informs about the number of charges needed to generate a unit of electric flux for a given medium.
Permittivity = electrical displacement / electric field intensity
SI unit of electrical permittivity = Farad/meter
The least value of permittivity is found in a vacuum. This permittivity in a vacuum is known as the permittivity of free space or electric constant and is denoted by ϵ0 with the value 8.85✕ 1012 Farad/meter. Dielectric materials also possess permittivity properties as they have an electric field. Permittivity in dielectrics is dimensionless, represented by the ratio of absolute permittivity to the electric constant, and is denoted by
εr = ε / εo
where, ϵr is the relative permittivity
ϵ is the absolute permittivity of that material
ϵ0 is the electric constant
Coulomb’s law states that the twopoint charges q1 and q2 separated by distance r in free space have some magnitude of the electrostatic force between them. This force can be calculated by using relative permittivity. Using the ratio of the electrostatic force between these twopoint charges to the vacuum electrostatic force between the same twopoint charges is given by
Fa = q1 q2 / 4 π εo r2
Fr = q1 q2 / 4 π εo εr r2
Permeability of the material is the ability to allow the formation of magnetic fields or magnetic field lines of force. Thus, it tells about the material’s magnetizing properties when subjected to the magnetic field. In simpler words, we can define permeability as the extent of penetration of a magnetic field in a material or the conducting power of a material to conduct magnetic field lines. It is denoted by the Greek letter mu, μ.
SI unit of permeability = H/m or TmA1, where H is Henry
The dimensional formula of permeability = MLT2A
Permeability = magnitude of magnetic induction (B) / intensity of magnetic field (H)
The free space permeability is referred to as the permeability constant, given by μ0 = 4𝝅×107 H/m. It is a second rank tensor for anisotropic medium and is a scalar quantity. Permeability plays a significant role in classifying the magnetizing property of a medium. For example, if the magnetic permeability is less than μ0, the material is diamagnetic. Similarly, if the magnetic permeability is greater than μ0, then the material is said to be paramagnetic.


















In physics, permittivity and permeability both are significant in the electrical field and magnetic field respectively. They difference between them is described as under

















