What is Dielectric Constant?

It is also known as Relative permittivity. If two charges q ₁ and q ₂ are separated from each other by a small distance r. Then by using the coulombs law of forces the equation formed will be

———— 2.6

In the above equation is the electrical permittivity or you can say it, Dielectric constant.

If we repeat the above case with only one change i.e. only change in the separation medium between the charges. Here some material medium must be used. Then the equation formed will be.

——2.7
Now after division of equation 2.6 with equation 2.7 we get…
——2.8

In the above figure
is the Relative Permittivity. Again one thing to notice is that the dielectric constant is represented by the symbol(K) but permittivity by the symbol

Now after the division third equation is created. Its we describe this equation then the new definition can be made from this. i.e.
It is the ratio of the force of communication between the two point charges separated from each by a distance using air/Vacuum as a medium to the force of communication between the same charges placed at the same distance and using some material medium.
Faraday has done many experiments on this topic. He found that When we insert some insulating material in the space present between the plates of a capacitor , having its plates fully charged then the capacitance of the capcitor will increase definitely.

Values of dielectric constant varies with the change in materials. Some of the examples of materials is shown below in the table