Is resistance constant in Ohm's law?

Ohm’s law states that a current passing through a conductor is directly proportional to the voltage across it, provided the temperature remains constant. R that represents resistance is the constant of proportionality and has Ohms as its unit.


Related Questions:

  1. What is the necessary condition for a conductor to obey Ohm's Law?
  2. How do you find the resistance to Ohm's law?
  3. Why is the curve representing Ohm's law linear?

Read More:

CBSE CLASS XII Related Questions

  • 1.
    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 \[ \sigma = \frac{n e^2 \tau}{m}. \]


      • 2.
        Capacitors are manufactured with certain standard capacitances and working voltages. However, these standard values may not be the ones that are actually needed in a particular application. Two or more capacitors can be grouped in series or in parallel to achieve desired capacitance and voltage. When connected in series, the total capacitance decreases while the voltage rating increases, whereas in parallel connections, the total capacitance increases and maintains the same voltage rating. A capacitor stores energy in the electric field between its plates and stored energy is proportional to the square of the voltage and capacitance $U = \frac{1}{2}CV^2$, where symbols have their usual meanings.
        Two capacitors, one of $3 \ \mu$F and the other of $6 \ \mu$F, are connected in series in the circuit as shown in the figure, for a long time. }


          • 3.
            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.


              • 4.
                Read the following paragraph and answer the questions that follow.
                In an experiment with convex lens of focal length f, the screen is fixed at a distance D from the object. A student slowly moves the lens away from the object towards the screen and finds that she is able to form sharp image of the object for two positions of the lens. The distance between these two positions of the lens is d.


                  • 5.
                    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 $\frac{1}{4\pi\epsilon_0} \frac{(q_1 + q_2) (r_1 + r_2)}{r_1 r_2}$

                    • 6.
                      With the help of a labelled diagram, explain the principle, construction and working of an a.c. generator.

                        CBSE CLASS XII Previous Year Papers

                        Comments


                        No Comments To Show