How does a potentiometer measure EMF?

The EMF of a cell can be measured using a potentiometer by obtaining the balancing length (l). The fall of the potential along the length of the wire is equivalent to the emf of the cell, as no current is drawn from the cell.

CBSE CLASS XII Related Questions

  • 1.
    Assertion (A) : All atoms have a net magnetic moment. Reason (R) : A current loop does not always behave as a magnetic dipole.

      • Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
      • Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
      • Assertion (A) is true, but Reason (R) is false.
      • Both Assertion (A) and Reason (R) are false.

    • 2.
      Two heaters rated as \((P_1,V)\) and \((P_2,V)\) are connected in series across a dc source of \(V/2\) volt. The power consumed by the combination will be –

        • \((P_1+P_2)\)
        • \(\dfrac{P_1+P_2}{2}\)
        • \(\dfrac{P_1P_2}{2(P_1+P_2)}\)
        • \(\dfrac{P_1P_2}{4(P_1+P_2)}\)

      • 3.
        Four independent waves are expressed as \[ (i)\; y_1=A_1\sin\omega t, \] \[ (ii)\; y_2=A_2\sin 2\omega t, \] \[ (iii)\; y_3=A_3\cos\omega t, \] \[ (iv)\; y_4=A_4\sin\left(\omega t+\frac{\pi}{3}\right) \] The interference between two of these waves is possible in

          • (i) and (iii) only
          • (iii) and (iv) only
          • (i), (iii) and (iv) only
          • All of them

        • 4.
          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° in 0.2 s. The value of emf induced in the loop will be:

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

          • 5.
            The figure shows three point charges kept at the vertices of triangle ABC. The net electric field, due to this system of charges, at the midpoint M of base BC will be:

              • \( \frac{q}{4 \pi \epsilon_0 l^2} \) pointing along MA
              • \( \frac{q}{\pi \epsilon_0 l^2} \) pointing along AM
              • \( \frac{q}{2 \pi \epsilon_0 l^2} \) pointing along AM
              • Zero

            • 6.
              Write any two features of nuclear forces.

                CBSE CLASS XII Previous Year Papers

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