Dipole Moment

It is a vector quantity whose magnitude is equal to the product of charge (q) and separation between the charges (2a).

p = q x 2a  or  |p| = q2a

• Its SI unit is Coulomb-metre (C-m).

• Its direction is from -q to +q.

• The dipole field at large distances falls off as 1/r³.

• The direction of the dipole field depends not only on distance r but also on the angle between the position vector r and the dipole moment p.

• Point dipole - When the dipole size 2a becomes zero, the charge q becomes infinity in such a way that the product p = q x 2a is finite then, it is said to be a point dipole or an ideal dipole.