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1. DIELECTRIC

2. What is Dielectrics?
dia - passing through
electric - electric field
WILLIAM WHEWELL – a scientist and a philosopher
from the 19th century

3. DEFENITION OF DIELECTRIC
Dielectric is an insulating material of very poor
conductor of electric current.

4. What is the difference between dielectric
and insulator?
The material which stores the electrical energy in an
electric field is known as the dielectric material,
whereas the material which blocks the flow of
electrons is known as the insulators.

5. PROPERTIES OF DIELECTRICS
Insulating ability
- Dielectrics prevent the flow of electric current and are valued for their high electrical
resistance.
 Polarization
- Dielectrics can be polarized by an applied electric field, leading to the alignment of charges
within the material.
 Permittivity and susceptibility
- Permittivity refers to a material's ability to permit the electric field, while susceptibility
measures the degree of polarization.

6. Types of Dielectrics
Linear vs. non-linear dielectrics
- Linear dielectrics exhibit a proportional response to the applied electric field,
while non-linear dielectrics show a more complex relationship.
Homogeneous vs. heterogeneous dielectrics
- Homogeneous dielectrics have uniform properties throughout, whereas
heterogeneous dielectrics have variations in composition.

7. CLASSIFICATION OF DIELECTRIC

8. POLAR DIELECTRICS
Assymetric arrangement of atoms, which means centers of gravity
of positive and negative charges don’t coincide, even in absence of
external field.
Polar dielectrics are polar compounds that do not conduct
electricity.
Ex. Ammonia, and HCI

9. NONPOLAR DIELECTRICS
Symmetric arrangement of atoms, which means centers of gravity
of positive and negative charges coincide in absence of external
electric field.
Nonpolar dielectrics are nonpolar compounds that cannot conduct
electricity.
Ex. Benzene, methane, carbon dioxide

11. POLARIZATION
When a dielectric material is placed in an electric field, the
positive and negative charges within the atoms or
molecules are separated, creating an electric dipole
moment. This phenomenon is known as polarization.

12. Polarization Mechanisms
Orientation polarization
- Polarization due to the alignment of molecules with an external electric field.
 Electronic polarization
- Polarization caused by the displacement of electrons within atoms or
molecules.
 Ionic polarization
- Polarization resulting from the movement of ions in response to an electric
field.

13. ELETRONIC POLARIZATION
In atoms or molecules, electrons can be displaced
from their equilibrium positions, creating an induced
dipole moment.

14. DIELECTRIC IN AN ELECTRIC FIELD
 Dipole moment: p = q x d
 Note that p, the electric
dipole moment, is a vector: it
has direction.
 Where q is the (absolute
value of the) charge of
electron cloud that was
displaced.

15. IONIC POLARIZATION
Ionic polarization occurs in ionic compounds, in which the
oppositely charged ions move in opposite directions under the
influence of the electric field to produce a net dipole moment in
them.
This type of polarization typically occurs in ionic crystal elements
such as NaCl, KCl, and LiBr.

16. IONIC POLARIZATION
To undergo ionic polarization, a material must
have an ionic structure, it must be composed of
cations and anions.
This ion pair already possesses a dipole moment
before the application of the electric field.

17. The applied field causes the bond to
stretch.
IONIC POLARIZATION
Reverse field: this field causes compression of
the bond and thus decrease the dipole
moment.

18. ORIENTATIONAL POLARIZATION
Oriental polarization occurs in polar substannces. These substamce
exhibit dipole moment even in the absence of external electric field.
When such materials are subjected to an external electric field, the
permanent molecular dipoles rotate about their axis of symmetry to
align with the applied field.
Ex: H2O in its liquid form

19. ORIENTAL POLARIZATION
Some molecules possess a permanent dipole there is always a separation of charge within the
molecule, even in the absence of an electric field. The example shown here is H2O.

20. ORIENTAL POLARIZATION
Consider a material containing many such
dipoles. In naturally non- polar materials
like water, the dipoles are randomly
arranged as a result of thermal motion.
Therefore the dipole moments from
different molecules cancel out and the net
polarization is zero.

21. ORIENTAL POLARIZATION
The dipoles rotate in order to align with
the electric field. As a result, they also
align with each other. Dipole moments
no longer cancel out, and the material
develops a net polarization.

22. SPACE CHARGE POLARIZATION
The space charge, or interfacial polarization, is produced by the separation of mobile positively
and negatively charged particles under an applied field, which form positive and negative space
charges in the bulk of the material or at the interfaces between different materials.

23. Dielectrics in Capacitors
A capacitor is a device used for storing charge. It normally consists of two conducting plates
with a dielectric material between them, although an “empty capacitor” – one with a vacuum
between the plates – may also be used in some applications.
Capacitors consist of two conductive plates separated by a dielectric, storing energy in an
electric field.

24. DIELECTRIC CONSTANT
The dielectric constant of a material provides a measure of its effect on a
capacitor. It is the ratio of the capacitance of a capacitor containing the dielectric
to that of an identical but empty capacitor.
Permittivity is a quantity that describes the effect of a material on an electric
field: the higher the permittivity, the more the material tends to reduce any field
set up in it.

25. Dielectric Strength
 Dielectric strength is the ability of a material to withstand electric
stress without undergoing breakdown.
Factors affecting dielectric strength
- Factors include material purity, temperature, and thickness.

26. DIELECTRIC LOSS
Dielectric loss is the dissipation of energy through the movement of charges in
an alternating electromagnetic field as polarization switches direction.

27. Dielectric Breakdown
Dielectric breakdown is the sudden failure of a dielectric material, leading to
the loss of its insulating properties.
Factors influencing breakdown strength
- Factors include material composition, temperature, and applied electric field
strength.

28. APPLICATION OF DIELECTRICS
 A major use of dielectrics is in fabricating capacitors. These have
many uses including storage of energy in the electric field between
the plates, filtering out noise from signals as part of a resonant
circuit, and supplying a burst of power to another component.

29. SUMMARY
Dielectrics are electrical insulators that support charge.
The properties of dielectrics are due to polarization.
There are three main mechanisms by which polarization arises on the microscopic scale: electronic (distortion of
the electron cloud in an atom), ionic (movement of ions) and orientational (rotation of permanent dipoles).
A capacitor is a device that stores charge, usually with the aid of a dielectric material. Its capacitance is defined
by Q = C V
The dielectric constant κ indicates the ability of the dielectric to polarize. It can be defined as the ratio of the
dielectric’s permittivity to the permittivity of a vacuum.
The dielectric constant is also affected by structure, as this affects the ability of the material to polarize.
Polar dielectrics show a decrease in the dielectric constant as temperature increases.
Dielectric loss is the absorption of energy by movement of charges in an alternating field, and is particularly high
around the relaxation and resonance frequencies of the polarization mechanisms.
Sufficiently high electric fields can cause a material to undergo dielectric breakdown and become conducting.

30. THANK YOU!
SANA MAY NATUTUNAN KAYO