PRESENTATION ON DIELECTRIC MATERIALS AND INTERNAL FIELD

1. DIELECTRIC MATERIALS AND
INTERNAL FIELD
M.VINOTHINI
22ECR232

2. COMPONENTS
Internal field
Clausius Mossotti’s equation
Dielectric Loss
Causes Of Dielectric Loss
Uses Of Dielectric Material In Capacitors
Types Of Capacitors and Their Dielectrics
Advantages And Applications of Dielectric Materials in Capacitors

3. Internal fields
• In dielectric solids, the atoms or
molecules experience not only the
external applied electric field but also
the electric field produced by the
dipoles.
• The resultant electric field acting on the
atoms or molecules of dielectric
substance is called the local field or an
internal field.

4. Consider a dielectric material and is subjected to external field of intensity
E1. The charges are induced on the dielectric plate and the induced electric
field intensity is taken as E2. Let E3 be the field at the center of the material.
E4 be the induced field due to the charges on the the spherical cavity. The
total internal field of the material is

5. Now consider the Electric field intensity applied E1
Here the charge is induced due to the induced field so the electric
flux density D changes to the electric polarization P
Since we have considered that the specimen is non polar dielectric material, at
the center of the specimen the dipole moment is zero and hence the electric field
intensity at the center is zero due to symmetric structure.

6. Now consider a circle from the center of the dielectric material. In order to calculate
the electric field intensity E4 on the surface of spherical cavity, the polarization
should be calculated by resolving it into two components,
The charge changes to dq where the area of cross section changes to
ds
The Electric field intensity E is given by
Substituting the values RQ and QS in the surface area we
get,
The polarization P is the induced charge per unit area

7. Substituting all the values in the electric field intensity on the spherical
cavity E4
Integrating with in the limits 0 to π,
The total electric field is given by
The Internal field obtained is given as

8. Clausius Mossotti’ s equation:
It gives the relation between the dielectric constant and the ionic polarizability of
atoms in dielectric material. If there are N number of atoms, the dipole moment per
unit volume which is called Polarization is given by
From internal field
The relation between polarization and dielectric constant
From the above two equations we get,

9.  Dielectric Loss refers to the Loss of energy that goes into heating a Dielectric material in
a varying, electric field.
 It tends to depend mainly on the Dielectric material and the frequency.
 Dielectric Loss is measured using the Loss of tangent which is also commonly referred to
as tan delta (tan δ).
In conduction loss, a flow of charge through the material
causes energy dissipation.
 Dielectric loss is the dissipation of energy through the
movement of charges in an alternating electromagnetic field
as polarisation switches direction.
Causes of dielectric loss:
Dielectric loss:

10. Dielectric materials are used in capacitor to increase the capacitance of
the capacitor.
1.Ceramic Capacitors
1. Dielectric Material: Ceramic (usually made from barium
titanate or other metal oxides).
2. Uses: Widely used in high-frequency applications, bypass
capacitors, and decoupling circuits.
2.Electrolytic Capacitors
1. Dielectric Material: Aluminium oxide (anodized layer on
aluminium plates).
2. Uses: Mainly used in power supply circuits due to their
high capacitance values.
3.Film Capacitors
1. Dielectric Materials: Polyethylene terephthalate (PET),
Polypropylene (PP), or Polytetrafluoroethylene (PTFE).
2. Uses: Used in audio applications, motor-run capacitors,
and high-temperature environments.
Uses of Dielectric Materials in Capacitors:
Types of Capacitors and Their
Dielectrics:

11. •Increased Capacitance: Dielectrics allow for
higher capacitance values in compact sizes,
maximizing energy storage capacity.
•Voltage Endurance: Dielectric materials
enhance the capacitor's ability to withstand
high voltages without breakdown.
•Low Losses: Good dielectrics minimize
energy loss through heat dissipation, making
capacitors more efficient.
Advantages of Dielectric Materials in Capacitors:

12. 1.Power Electronics: Capacitors in power
converters, inverters, and motor drives.
2.Audio Systems: Coupling and filtering
capacitors in audio equipment.
3.Radio Frequency (RF) Circuits: Capacitors for
coupling, tuning, and impedance matching.
4.Energy Storage: Supercapacitors with high
dielectric constants for quick energy release.
Applications of Capacitors with Dielectric
Materials:

13. THANK YOU
SUBMITTED BY :
M.VINOTHINI
22ECR232