 # Explain what is electric dipole moment?

An electric dipole is characterised by a vector quantity$$\vec{p}$$called the electric dipole moment which is defined by

$$\vec{p}= q\times2\vec{a}$$

where

q – The magnitude of the charge

2a – The separation between two charges

An electric dipole is created by the combination of equal and opposite charges by a separation of a certain distance.

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 $$\vec{p}$$ is directed from the negative to the positive charge.

Dimensional Formula of p

The direction of the dipole moment is always from the negative charge to the positive charge.  The dimensional formula of an electric dipole is

The dimensional formula of magnetic or electric dipole moment is given by,

[M0 L1 TI1]

Where,

• M = Mass
• I = Current
• L = Length
• T = Time

Units of p

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

(ii) The practical unit of p is called debye (D) (0) (0)