Explain the relation between current and drift velocity.

Relation between Current and Drift Velocity

  • The electrons move with an average velocity that is independent of time, although electrons get accelerated.
  • This is because an electron suffers collisions with heavy fixed ions, however, after the collision, it will emerge at the same speed in random directions.
  • This average velocity of electrons is known as the drift velocity.

The relation between current and drift velocity is,

I = neAvd

  • where, n refers to the number of free electrons per unit volume,
  • e is the charge of an electron,
  • A is the planar area located inside the conductor.

Related Questions

  1. Give two examples of drift velocity.
  2. What is the relation between drift velocity and electric field?
  3. 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.
  4. What Are Two Kinds Of Electricity?
  5. 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.
    In a region, the electric potential varies as \(V = 10 - 50x\), where \(V\) is in volts and \(x\) is in meters. The electric field in the region is

      • \(10\ \text{N/C}\) along \(+x\)
      • \(10\ \text{N/C}\) along \(-x\)
      • \(50\ \text{N/C}\) along \(+x\)
      • \(50\ \text{N/C}\) along \(-x\)

    • 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.
          A current of \(4.0\,\text{A}\) flows through a wire of length \(1\,\text{m}\) and cross-sectional area \(1.0\,\text{mm}^2\), when a potential difference of \(2\,\text{V}\) is applied across its ends. Calculate the resistivity of the material of the wire.


            • 4.

              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.


                • 5.
                  Draw the plot of potential energy of a pair of nucleons as a function of their separation. Write two important conclusions that can be drawn from this plot.


                    • 6.
                      Two point charges -Q and Q are located at points (d, 0) and (0, d) respectively, in x-y plane. The electric field E at the origin will be:

                        • \(\frac{1}{4\pi\epsilon_0} \frac{\sqrt{2}Q}{d^2} (\hat{i} - \hat{j})\)
                        • \(\frac{1}{4\pi\epsilon_0} \frac{\sqrt{2}Q}{d^2} (-\hat{i} - \hat{j})\)
                        • \(\frac{1}{4\pi\epsilon_0} \frac{Q}{d^2} (\hat{i} - \hat{j})\)
                        • \(\frac{1}{4\pi\epsilon_0} \frac{Q}{d^2} (-\hat{i} - \hat{j})\)
                      CBSE CLASS XII Previous Year Papers

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