UNIT I
Dielectric Properties of Insulating Materials
Parameters of Dielectric material
Introduction to Polar and Non- Polar dielectric materials
Mechanisms of Polarizations-Electronic, Ionic and
Orientation Polarization
Clausius Mossotti Equation,
Piezo-Electric, Pyro-Electric & Ferro-Electric Materials
Dielectric loss and loss tangent
Dielectric Material:
The material which are insulators and can store energy
with minimum dissipation are called as dielectric material
Dielectric material are capable of storing electrical charges
Dielectric material mainly used in capacitor, cables etc.
All dielectric material insulating material but all insulating
material are not dielectric
Dielectric material can be polarized by the application of
electric field
Electric flux Density (D):
Electric flux density is defined as charge per unit area and
it has same units of dielectric polarization.
Electric flux density D at a point in a free space or air in
terms of Electric field strength is
D0 0 E - - (1)
At the same point in a medium is given by
D E - - (2)
, Parameters of Dielectric
Dipole Moment
Dielectric constant
Polarization
Polarizability
Dipole Moment :
An electric dipole comprises of two equal and opposite
point charges that are separated by a distance d. The
resulting dipole moment, µ is expressed as
The product of magnitude of either of the charges and
separation distance b/w them is called Dipole moment.
µe = q . d coul – m
All dielectrics are electrical insulators and they are mainly
used to store electrical energy.
Deybe = 3.336X10-30 Cm
Dipole moment is a vector originated from negative charge
towards positive charge.
Dielectric Constant:
Dielectric Constant is the ratio between the permittivity of the
medium to the permittivity of free space.
r
0
Consider a parallel plate capacitor having area of each plate is
a . and distance between the plate is d .
, 𝑎∈0
𝐶 =
𝑑
∈ = 𝑝𝑒𝑟𝑚𝑖𝑡𝑡𝑖𝑣𝑖𝑡𝑦 𝑜𝑓 𝑓𝑟𝑒𝑒 𝑠𝑝𝑎𝑐𝑒
If the space is filled with dielectrics ,
Then the capacitance of capacitor is
given by
𝒂∈𝟎 ∈𝒓
C= 𝒅
𝐶
∈𝑟 =
𝐶
Since, it is the ration of same quantity, it is unit less .
For any dielectric material the value of dielectric is always
greater than 1.
The value of dielectric constant is independent of siza or shape
of the dielectric material
Polarization:
The process of producing electric dipoles by an electric field is
called polarization in dielectrics
=
Unit 𝐶 𝑟
=
𝑟
= 𝑐⁄𝑚
Dielectric Properties of Insulating Materials
Parameters of Dielectric material
Introduction to Polar and Non- Polar dielectric materials
Mechanisms of Polarizations-Electronic, Ionic and
Orientation Polarization
Clausius Mossotti Equation,
Piezo-Electric, Pyro-Electric & Ferro-Electric Materials
Dielectric loss and loss tangent
Dielectric Material:
The material which are insulators and can store energy
with minimum dissipation are called as dielectric material
Dielectric material are capable of storing electrical charges
Dielectric material mainly used in capacitor, cables etc.
All dielectric material insulating material but all insulating
material are not dielectric
Dielectric material can be polarized by the application of
electric field
Electric flux Density (D):
Electric flux density is defined as charge per unit area and
it has same units of dielectric polarization.
Electric flux density D at a point in a free space or air in
terms of Electric field strength is
D0 0 E - - (1)
At the same point in a medium is given by
D E - - (2)
, Parameters of Dielectric
Dipole Moment
Dielectric constant
Polarization
Polarizability
Dipole Moment :
An electric dipole comprises of two equal and opposite
point charges that are separated by a distance d. The
resulting dipole moment, µ is expressed as
The product of magnitude of either of the charges and
separation distance b/w them is called Dipole moment.
µe = q . d coul – m
All dielectrics are electrical insulators and they are mainly
used to store electrical energy.
Deybe = 3.336X10-30 Cm
Dipole moment is a vector originated from negative charge
towards positive charge.
Dielectric Constant:
Dielectric Constant is the ratio between the permittivity of the
medium to the permittivity of free space.
r
0
Consider a parallel plate capacitor having area of each plate is
a . and distance between the plate is d .
, 𝑎∈0
𝐶 =
𝑑
∈ = 𝑝𝑒𝑟𝑚𝑖𝑡𝑡𝑖𝑣𝑖𝑡𝑦 𝑜𝑓 𝑓𝑟𝑒𝑒 𝑠𝑝𝑎𝑐𝑒
If the space is filled with dielectrics ,
Then the capacitance of capacitor is
given by
𝒂∈𝟎 ∈𝒓
C= 𝒅
𝐶
∈𝑟 =
𝐶
Since, it is the ration of same quantity, it is unit less .
For any dielectric material the value of dielectric is always
greater than 1.
The value of dielectric constant is independent of siza or shape
of the dielectric material
Polarization:
The process of producing electric dipoles by an electric field is
called polarization in dielectrics
=
Unit 𝐶 𝑟
=
𝑟
= 𝑐⁄𝑚
