Download (4Mb) - Etheses - Saurashtra University

Chapter V Dielectric Study of ……
-
dipole moment of a molecule exhibited in the absence of external electric
field.
Irrespective of the results obtained in the study of electrical properties
of materials, its polarity can be judged from the chemical structure of its
molecules. An experimental definition of the dipole moment µ leads to very
important conclusions regarding the structure of the molecules of materials.
The atom has a positively charged nucleus surrounded by an electron cloud.
Due to symmetry in non-polar dielectric substance, in the absence of electric
field, the centers of positive and negative charges coincide. As a result of this
l = 0 in the molecules of non-polar dielectric material and hence µ = 0.
Conversely, the asymmetric molecules are always polar dielectric.
Figure: 5.2 Formation of dipole in non-polar dielectric in electric field.
Figure (5.2) shows formation of dipole in non-polar dielectric material
when placed in electric field. When an electric field is applied, the centers of
positive and negative charges are separated from each other due to the
influence of electric force acting on them in mutually opposite directions. This
induces an electric dipole.
Figure: 5.3 Molecules structure of (a) KI, (b) CO2 and (c) H2O.
The mono-atomic molecules (He, Ne, Ar, Kr, Xe) and molecules
consisting of two identical atoms linked by a homo-polar bond (H2, N2, Cl2) are
189