# Explain what is electric dipole moment?

An electric dipole is characterised by a vector quantity $left( overrightarrow{p} right),$ called the electric dipole moment which is defined by

$overrightarrow{p}=qleft( 2overrightarrow{a} right)=2q,overrightarrow{a}$

Where $2overrightarrow{a}$ is the vector displacement from the negative to the positive charge?

Electric dipole moment is thus the product of the magnitude of either of the charges and the vector displacement from the negative to the positive charge.

Clearly, the electric dipole moment $overrightarrow{p}$ is directed from the negative to the positive charge.

Dimensional Formula of p

As $p=qtimes 2a$ and $q=left[ AT right]$ and $2a=left[ L right],$ dimensional formula of p is $left[ {{M}^{0}}{{L}^{1}}{{T}^{1}}{{A}^{1}} right].$

Units of p

(i) The SI unit of p is Coulomb metre (C m)

(ii) The practical unit of p is called debye (D)