Question

Why electric field inside a dielectric decreases due to polarisation?

Answer 1

The electric field inside a dielectric decreases due to polarization because of the way the dielectric material responds to the applied electric field.

Here’s how it works in simple terms:

1. Polarization of the dielectric: When you apply an electric field to a dielectric material, the electric field causes the positive and negative charges within the dielectric to shift slightly. This shift creates tiny dipoles (pairs of positive and negative charges) within the material. This process is called polarization.
   

1. Opposing electric field: The newly formed dipoles create their own electric field. Importantly, the direction of this field is opposite to the applied electric field. This is because the negative charges in the dipoles are attracted to the positive part of the applied field, and the positive charges are attracted to the negative part.
   

1. Reduction in the total field: The electric field created by these induced dipoles (the polarization field) acts in the opposite direction to the original electric field. As a result, the total electric field inside the dielectric is reduced. The reduction depends on how strong the polarization is, which in turn depends on the dielectric constant of the material.
   

1. Dielectric constant: The degree to which the dielectric reduces the internal electric field is quantified by the dielectric constant (also called the relative permittivity) of the material. A material with a higher dielectric constant polarizes more strongly, which leads to a greater reduction of the electric field inside it.
   

In summary, the electric field inside a dielectric decreases because the material polarizes in response to the applied electric field, and the resulting opposing field from the dipoles reduces the net field inside the dielectric.