The **electric dipole moment** of a given charge distribution is a measure of the separation between the positive and negative charges in the system. The dipole moment is the first term in a multipole expansion. Electric dipole moment is measured in Coulomb-meters (C m) in the SI system. Electric dipole moment is a vector quantity. Given two point charges of equal magnitude *q* and separation **d** (the displacement vector pointing towards the positive charge), the electric dipole moment is equal to

More generally, for a distribution of charge *ρ*, the electric dipole is equal to

where **r** is the position vector and **r _{0}** is any given point. For a collection of point charges, the dipole moment is equal to

An electric dipole placed in an electric field will experience a torque equal to

and will have potential energy

The electric potential at a point at a distance **r** from a dipole will be