What are the limitations of Ohm's Law?

Ohm's law states that electric current is directly proportional to the voltage and is inversely proportional to resistance. The current-voltage relationship can be denoted as V = IR where V is voltage, I is current, and R is resistance.

Limitations of Ohm's Law

The limitations of ohm’s law are – 

  • Ohm's law doesn’t apply to unilateral electrical components like diodes as well as transistors even though they only permit current to flow just in one way.
  • The level of voltage will not be constant with respect to time for nonlinear electrical components having properties such as resistance, capacitance, etc which makes Ohm’s law difficult to apply.

For example:

  • Semiconductors such as Germanium and Silicon don’t obey Ohm’s law and are therefore called Non-Ohmic conductors.
  • A water volt-ammeter is a unilateral network, therefore Ohm’s law is not applicable to such networks.

Related Questions:

  1. What is the necessary condition for a conductor to obey Ohm's Law?
  2. Why is the curve representing Ohm's law linear?
  3. How do you find the resistance to Ohm's law?
  4. What are the 3 forms of Ohm's law
  5. Is resistance constant in Ohm's law?

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CBSE CLASS XII Related Questions

  • 1.
    Two metal spheres of radii $r_1$ and $r_2$ ($> r_1$) having charges $q_1$ and $q_2$ respectively kept in air, are brought in contact. Which of the following statements is not correct ?

      • The total charge of the two spheres is conserved.
      • Both spheres attain the same potential.
      • The final potential of the system equals $\frac{1}{4\pi\epsilon_0} \frac{(q_1 + q_2)}{(r_1 + r_2)}$
      • The final potential of the system equals $\frac{1}{4\pi\epsilon_0} \frac{(q_1 + q_2) (r_1 + r_2)}{r_1 r_2}$

    • 2.
      The resistance of a metal wire at \( 20^\circ \text{C} \) is \( 1.05 \, \Omega \) and at \( 100^\circ \text{C} \) is \( 1.38 \, \Omega \). Determine the temperature coefficient of resistivity of this metal.


        • 3.
          Write two advantages of reflecting telescope over refracting telescope.


            • 4.
              A student sets up the circuit as shown in the figure to find the value of unknown resistance X and records a set of readings of the voltmeter and the ammeter by using the rheostat.


                • 5.
                  Read the following paragraph and answer the questions that follow.
                  A p-type or n-type semiconductor can be converted into a p-n junction by doping it with suitable impurity. The motion of majority charge carriers causes diffusion current across the junction while the barrier electric field causes motion of minority carriers for drift current. In case of unbiased diode, the diffusion and drift currents are equal. This equilibrium is disturbed by the biasing batteries. Diodes, therefore, allow currents in one direction. This property of diode is used in making rectifiers.


                    • 6.
                      Consider the nuclear reaction \( X \to Y + Z \). Let \( M_x \), \( M_y \), and \( M_z \) be the masses of the three nuclei X, Y, and Z respectively. Then which of the following relations hold true?

                        • \( (M_x - M_z)<M_y \)
                        • \( (M_x - M_y)<M_z \)
                        • \( M_x>(M_y + M_z) \)
                        • \( M_x<(M_y + M_z) \)
                      CBSE CLASS XII Previous Year Papers

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