What is Electric Dipole Moment?

An electric dipole is a system formed by a pair of equal and opposite point charges (+q and -q) separated by a small, finite distance (often denoted as 2a or d). Molecules like HCl or H₂O are common examples, where one atom is slightly positive and the other is slightly negative.

The electric dipole moment (symbolized by the vector p) is a measure of the strength and orientation of this dipole. It quantifies the overall polarity of the system.

• Definition: The electric dipole moment is defined as the product of the magnitude of either charge (q) and the vector representing the separation distance (d) between them.
• Formula: p = q × d (or p = q × 2a)
• Vector Direction: The electric dipole moment is a vector quantity. Its direction is defined by convention to point from the negative charge (-q) to the positive charge (+q).
• Conceptual Meaning: A non-zero dipole moment indicates a separation of positive and negative charge centers. A larger dipole moment means the charge separation is greater (either the charges are larger or they are farther apart), resulting in a more "polar" system. If the positive and negative charge centers are in the same place (like in a N₂ or O₂ molecule), the dipole moment is zero.