(a) Explain briefly, using a proper diagram, the difference in behaviour of a conductor and a dielectric in the presence of external electric field.
(b) Define the term polarization of a dielectric and write the expression for a linear isotropic dielectric in terms of electric field.
(a) For the conductor ;
Since the internal electric field is equal and opposite to the external field in a conductor the net electric field inside the conductor is zero.
For dielectric ;
Due to the alignment of atomic dipoles (permanent or induced ) along the electric field, the net electric field within the dielectric decreases and do not cancel.
(b) The net dipole moment developed per unit volume in the presence of an external electric field is called the polarization ()
Where
is the electric susceptibility of the dielectric medium.