Define electric dipole and electric dipole moment.

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Jasmine Grover

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What is an Electric Dipole?

An electric dipole is a pair of equal and opposite electric charges separated by a small distance. This separation between the charges creates a dipole moment, which is a measure of the strength of the electric dipole.

Define electric dipole moment.

The dipole moment is defined as the product of the magnitude of one of the charges and the separation distance between the charges, multiplied by a unit vector pointing from the negative charge to the positive charge.

Mathematically, the electric dipole moment (p) is given by the formula:

μ = Q × r

where Q is the magnitude of the electric charge, and r is the distance between two charges.

Electric Dipole

Electric Dipole

The electric dipole moment is a vector quantity, meaning that it has both magnitude and direction.

  • The direction of the dipole moment is from the negative charge to the positive charge, and its magnitude depends on the strength of the charges and the distance between them.
  • Electric dipoles are important in many areas of physics and engineering, including electromagnetism, quantum mechanics, and molecular biology.
  • They are used to describe the behavior of electric fields in different materials and in different situations, and are also important in the design of electrical devices and in the study of chemical bonding.

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CBSE CLASS XII Related Questions

  • 1.
    A charged particle $+q$ in an electric field $\vec{E}$ experiences a force in the direction of the electric field. As a result, its kinetic energy changes. Similarly, the charged particle also experiences a force when it moves in a magnetic field $\vec{B}$. But this magnetic force is perpendicular to both velocity $\vec{v}$ of the charged particle and the magnetic field $\vec{B}$, so it cannot change the kinetic energy of the charged particle. Consider two charged particles 1 and 2 of masses $m$ and $\frac{m}{2}$ having charges $-q$ and $+2q$ respectively. They are accelerated from rest through the same potential difference $V$ and acquire kinetic energy $K_1$ and $K_2$. Then they enter in a region of uniform magnetic field $\vec{B}$ perpendicular to their velocities.


      • 2.
        Consider a cylindrical conductor of length \( l \) and area of cross-section \( A \). Current \( I \) is maintained in the conductor and electrons drift with velocity \( \vec{v}_d \, (|\vec{v}_d| = \frac{eE}{m} \tau) \), where symbols have their usual meanings. Show that the conductivity of the material of the conductor is given by \[ \sigma = \frac{n e^2 \tau}{m}. \]


          • 3.
            An electric field $\vec{E}$ is established across the ends of a cylindrical conductor of length L and area of cross-section A. Discuss how electrons attain an average velocity, independent of time. Hence, obtain a relation between current in the conductor and this ‘average velocity’ of electrons.


              • 4.
                An astronomical telescope consists of two converging lenses. One of them of large aperture and large focal length is called objective lens and the other one, of smaller focal length and smaller aperture is called the eyepiece. It is used to see distant objects which are not seen clearly with naked eyes. The image formed by the objective lens acts as an object for the eyepiece and the final image produced by the eyepiece is magnified.


                  • 5.
                    With the help of a labelled diagram, explain the principle, construction and working of an a.c. generator.


                      • 6.
                        Derive an expression for the capacitance of a parallel plate capacitor of plate area A and plate separation d with air present between the plates.

                          CBSE CLASS XII Previous Year Papers

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