Electric Dipole :-
‘ A system of charges, equal in magnitude and opposite in nature, which are placed vary close to each other is called electric dipole’
In fig. an electric dipole is shown. It is made up of two point charges +q and –q which are kept at 2a distance apart.
The distance between two charges is called ‘dipole length’ and the line joining the two charges of dipole is called axis of dipole.
Electric dipole moment :-
‘the product of magnitude of either charges of dipole and length of dipole is called electric dipole moment’
It is denoted by p . If the distance between two charges +q and –q of the dipole is 2a then magnitude of electric dipole moment is
P = q×2a = 2qa
Thus, electric dipole moment is a vector quantity. Its direction is form negative charge to positive charge of dipole.
Unit: in SI system the unit of electric dipole moment is ‘ Coulomb × metre’