Define the drift velocity of electrons in a conductor?

Drift Velocity is the average velocity attained by electrons, the charged particles, in a material due to an electric field. The drift velocity can be calculated using the following formula:

I = nAvQ

where,

  • v is the drift velocity of electrons
  • n is the number of electrons
  • A is the area of cross-section of a conductor
  • Q is the charge of an electron
  • I is the current flowing through the conductor.

Related Questions

  1. What is the relation between drift velocity and electric field?
  2. Two conducting wires X and Y of the same diameter but different materials are joined in series across a battery. If the number density of electrons in X is twice that in Y, find the ratio of the drift velocity of electrons in the two wires.
  3. Give two examples of drift velocity.
  4. Explain the relation between current and drift velocity.
  5. Define relaxation time of the free electrons drifting in a conductor? How is it related to the drift velocity of free electrons? Use this relation to deduce the expression for the electrical resistivity of the material.
  6. It is known that the drift velocity of electrons is only a few mm/s for a current of a few amperes. How is it possible that a current is established almost instantaneously when a circuit is closed? For example, a bulb glows as soon as the connection is switched on. Explain.

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CBSE CLASS XII Related Questions

  • 1.

    A square loop of side 0.50 m is placed in a uniform magnetic field of 0.4 T perpendicular to the plane of the loop. The loop is rotated through an angle of $60^\circ$ in 0.2 s. The value of emf induced in the loop will be:

      • 5 V
      • 3.5 V
      • 2.5 V
      • Zero V

    • 2.

      A ray of light MN is incident normally on the face corresponding with side AB of a prism with an isosceles right-angled triangular base ABC. Trace the path of the ray as it passes through the prism when the refractive index of the prism material is (i) $\sqrt{2}$, and (ii) $\sqrt{3}$.


        • 3.

          Find the ratio $\dfrac{\lambda_\alpha}{\lambda_p}$ of the de Broglie wavelength $\lambda_\alpha$ associated with an alpha particle to the de Broglie wavelength $\lambda_p$ associated with a proton if both are moving with the same velocity.


            • 4.

              The number of free electrons per unit volume ($\text{m}^3$) in a wire made of copper (resistivity $1.72 \times 10^{-8}\,\Omega\,\text{m}$) is $8.5 \times 10^{28}$. Calculate the average number of collisions made by an electron in one second when an electric field is maintained in the wire.


                • 5.

                  A rectangular loop of size 5 cm $\times$ 8 cm is lying in the $x$-$y$ plane in a uniform magnetic field $\vec{B} = (2.0\ \text{T})\hat{k}$. The total magnetic flux linked with the loop is:

                    • 80 Wb
                    • 16 Wb
                    • \(8 \times 10^{-2}\) Wb
                    • \(8 \times 10^{-3}\) Wb

                  • 6.

                    A magnet held vertically, with its north pole down, is dropped along the axis of a closed solenoid placed vertically on a table. If the observer looks down from the top,

                      • the induced current will flow in the anticlockwise direction.
                      • the induced current will flow in the clockwise direction.
                      • no induced current will flow in the solenoid.
                      • the magnet will fall with a constant velocity.
                    CBSE CLASS XII Previous Year Papers

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