Polarization of dielectrics
Criteria Polar Non-Polar
Centers of positive and negative charges
The centers are separated even in the absence of external electric field
The centers coincide
Dipole Moment
Permanent dipole moment
No permanent dipole moment
Examples
Dielectrics in External Electric Field
Hydro Chloric Acid ( HCl ) and Water ( H 2 O )
The individual dipole moments tend to align with the field . They develop a net dipole moment in the direction of the field .
Oxygen ( O 2 ) and Hydrogen ( H 2 )
Positive and negative charges get displaced . They develop an induced dipole moment as a restoring force against the direction of electric field .
Polarization of dielectrics
A dielectric develops a net dipole moment in the presence of an external field . The dipole moment per unit volume is called polarization and is denoted by P . For linear isotropic dielectrics ( substances where induced dipole moment is in the direction of the field and is proportional to the field strength ),