dielectric

What is Dielectric Constant?

When Dielectric slab is placed between parallel plate, the ratio of the applied electric field strength to the strength of the reduced value of electric field capacitor is called Dielectric Constant that is:




E is always less than or equal to E.

Where Eo is dielectric

And E is net field  

The larger the dielectric constant, the more charge can be stored. Completely filling the space between capacitor plates with a dielectric increases the capacitance by a factor of the dielectric constant:

C = κ Co, where Co is the capacitance with no dielectric between the plates.
 

Write the Dielectric constant for materials

Dielectric constant for selected materials (~300 K except where indicated)




Dielectric Strength

For an insulating material, the dielectric strength is that ,without breaking down maximum electric field strength that it can withstand intrinsically, that is, without experiencing failure of its insulating properties is known as DielectricStrength.



State the names and uses of material with  dielectric strength

Name and Uses of materials with high dielectric strength are:


for electric motor windings mica is used and its stator bars.


The glass and porcelain are widely used for high voltage transformers and transmission line connectors


Naphtha or Paraffin Oil is used when it is necessary.
 



Dielectric Polarisation

When an external electric field is applied to a dielectric material, its behavior can be determined and is known as Dielectric Polarizationthat can be understood by the displacement of charges(positive and negative) when an electric field is applied

The main task of the dielectric polarization is to relate macroscopic properties to microscopic properties. Where macroscopic property can be dielectric constant to polarizability

Polarization occurs through the action of an electric field or other external factors, such as mechanical stress in the case of piezoelectric crystals (piezoelectric crystals are those solid material which accumulates electric charge within them). Dielectric Polarization can also arise spontaneously in pyroelectric crystals, particularly in ferroelectrics(Ferroelectricity is a property of certain materials that have a spontaneous electric polarization that can be reversed by the application of an external electric field).