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Dielectrics is considered one of the most asked concept.
45 Questions around this concept.
When the air in a capacitor is replaced by a medium of dielectric constant K, the capacity,
In the absence of an applied electric field in nonpolar dielectric materials, charges are arranged in such a way that
In polar materials, dipole moment of all dipoles in the absence of electric field is
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The dielectric constant k of an insulator cannot be :
Dielectric: A dielectric is an insulating material in which all the electrons are tightly bounded to the nuclei of the atoms and no free electrons are available for the conduction of current. They are non-conducting materials. They do not have free charged particles like conductors have. They are of two types.
1. Polar : The centre of +ve and –ve charges do not coincide. Example HCl, , They have their own dipole moment
2. Non-Polar : The centers of +ve and –ve charges coincide. Example They do not have their own dipole moment.
When a dielectric slab is exposed to an electric field, the two charges experience force in opposite directions. The molecules get elongated and develops a surface charge density . This leads to development of an induced electric field Ep , which is in opposition direction of external electric field Eo . Then net electric field E is given by
This indicates that net electric field is decreased when dielectric is introduced.
The ratio is called dielectric constant of the dielectric. Hence, Electric field inside a dielectric is
.
This is irrespective of the thickness of the dielectric slab,i.e., whether it fills up the entire space between the charged plates or any part of it.
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