The dipole moment per unit volume is called polarization.
The alignment of the dipole moments of the permanent or induced dipoles with the direction of the applied electric field is called polarisation.
- There is an excess negative charge in one of the two extremely thin surface layers and an excess equivalent positive charge in the other.
- The induced charges on the surfaces of the dielectric are due to these layers.
- These charges are not free, but each is bound to a molecule lying in or near the surface. That is why these charges are called bound charges or fictitious charges.
- Within the remaining dielectric, the net charge per unit volume remains zero.
- Thus, although the dielectric is polarized, yet as a whole, it remains electrically neutral.