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.
    Two small identical metallic balls having charges \( q \) and \( -2q \) are kept far at a separation \( r \). They are brought in contact and then separated at distance \( \frac{r}{2} \). Compared to the initial force \( F \), they will now:

      • attract with a force \( \frac{F}{2} \)
      • repel with a force \( \frac{F}{2} \)
      • repel with a force \( F \)
      • attract with a force \( F \)

    • 2.
      In a Young's double-slit experiment, two waves each of intensity I superpose each other and produce an interference pattern. Prove that the resultant intensities at maxima and minima are 4I and zero respectively.


        • 3.
          The magnetic field in a plane electromagnetic wave travelling in glass (\( n = 1.5 \)) is given by \[ B_y = (2 \times 10^{-7} \text{ T}) \sin(\alpha x + 1.5 \times 10^{11} t) \] where \( x \) is in metres and \( t \) is in seconds. The value of \( \alpha \) is:

            • \( 0.5 \times 10^3 \, \text{m}^{-1} \)
            • \( 6.0 \times 10^2 \, \text{m}^{-1} \)
            • \( 7.5 \times 10^2 \, \text{m}^{-1} \)
            • \( 1.5 \times 10^3 \, \text{m}^{-1} \)

          • 4.
            A circular coil of 100 turns and radius \( \left(\frac{10}{\sqrt{\pi}}\right) \, \text{cm}\) carrying current of \( 5.0 \, \text{A} \) is suspended vertically in a uniform horizontal magnetic field of \( 2.0 \, \text{T} \). The field makes an angle \( 30^\circ \) with the normal to the coil. Calculate:
            the magnetic dipole moment of the coil, and
            the magnitude of the counter torque that must be applied to prevent the coil from turning.


              • 5.
                The energy of an electron in an orbit in hydrogen atom is \( -3.4 \, \text{eV} \). Its angular momentum in the orbit will be:

                  • \( \dfrac{3h}{2\pi} \)
                  • \( \dfrac{2h}{\pi} \)
                  • \( \dfrac{h}{\pi} \)
                  • \( \dfrac{h}{2\pi} \)

                • 6.
                  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 \[ \sigma = \frac{n e^2 \tau}{m}. \]

                    CBSE CLASS XII Previous Year Papers

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