Electric Dipole

Definition

An electric dipole is a separation of positive and negative electric charges within a system, typically a pair of equal and opposite charges separated by a small distance. This separation of charges creates an electric field and potential that are fundamental to understanding various phenomena in electromagnetism.

5 Must Know Facts For Your Next Test

1. The electric dipole moment is a vector quantity that describes the magnitude and direction of the separation between the positive and negative charges.
2. Electric dipoles can be created by the unequal distribution of electrons in a molecule, such as in water (H2O) or carbon dioxide (CO2).
3. The electric field of an electric dipole varies with the inverse cube of the distance from the dipole, unlike the inverse square law for a point charge.
4. Electric dipoles experience a torque when placed in an external electric field, which tends to align the dipole with the field.
5. The potential energy of an electric dipole in an external electric field is given by the dot product of the dipole moment and the electric field.

Review Questions

• Explain how an electric dipole creates an electric field and how this field differs from the field of a point charge.
  • An electric dipole consists of a pair of equal and opposite electric charges separated by a small distance. This separation of charges creates an electric field that varies with the inverse cube of the distance from the dipole, unlike the inverse square law for a point charge. The electric field lines of a dipole form a pattern that is more complex than the radial field of a point charge, with the field lines originating from the positive charge and terminating on the negative charge.
• Describe the potential energy of an electric dipole in an external electric field and how this energy depends on the orientation of the dipole.
  • The potential energy of an electric dipole in an external electric field is given by the dot product of the dipole moment and the electric field. This means that the potential energy is minimized when the dipole moment is aligned with the external field, and maximized when the dipole moment is perpendicular to the field. As a result, an electric dipole will experience a torque that tends to align it with the external electric field, in order to minimize its potential energy.
• Analyze how the electric field and potential of an electric dipole vary with distance and how this differs from the behavior of a point charge.
  • The electric field of an electric dipole varies with the inverse cube of the distance from the dipole, in contrast to the inverse square law for a point charge. This means that the electric field of a dipole falls off more rapidly with distance than the field of a point charge. Similarly, the electric potential of a dipole varies with the inverse square of the distance, compared to the inverse linear dependence for a point charge. These differences in the distance dependence of the field and potential are important for understanding the behavior of electric dipoles in various electromagnetic phenomena.

Related terms

Electric Charge:

The fundamental property of matter that causes it to experience a force when placed in an electric field. Charges can be positive or negative.

Electric Field:

A vector field that describes the force exerted on a positive test charge by an electric charge or charges at a given point in space.

Electric Potential:

The amount of work required to move a unit positive charge from infinity to a specific point in an electric field.