p^ is an unit vector which represents the direction of an electric dipole from negative charge to the positive charge. Why only in the direction from negative charge to the positive charge? What is the actual direction of p^ or the electric dipole? please explain in deep...
The actual direction of dipole moment is from -ve to +ve.
The reason that the electric dipole moment is directed from negative to positive is because of the definition of dipole moment:
q: charge ( charge of an electron , its is negative) .
d: distance from the origin of coordinates to the charge is positive .
Therefore , the product of -ve ( q ) and +ve (d) quantity will always be negative .
If you have a negative and positive charge, this relation gives you the direction from negative to positive.
Hope it helps !!