define electric dipole moment,
A dipole is simply defined as a system of two equal and opposite charges separated by a small distance. Every dipole possesses a dipole moment, which is defined as a product of charge and distance between two opposite charge. It is a vector quantity. Following is the figure of a dipole
Here, two equal and opposite charges q and (-q) are separated by a small distance 2a. The dipole moment of this dipole will be
Thus we can say that in a dipole, the positive and the negative charges are present separately. In molecules, a dipole is generated due to the difference in the electronegativities of the atoms forming the molecule.