How does a bridge circuit work?

The standard bridge circuit is known as a Wheatstone Bridge.
  • Wheatstone bridge is used to determine an unknown resistance by balancing the two legs of the bridge circuit, of which one leg includes the unknown resistance component.
  • Wheatstone bridge works on the null deflection principle, where the ratio of resistances is equal and no current flows through it.
  • Under normal conditions, the bridge remains unbalanced and the current flows through the galvanometer.
  • In a balanced condition, no current flows through the galvanometer by adjusting the values of the known and variable resistance.
  • When the current through a galvanometer is zero, the following condition exists I1P = I2R.

Wheatstone Bridge

To measure unknown resistance, a bridge circuit consists of a resistor with an unknown value and three resistors of known value. Either of the three known resistors is adjusted and then replaced until the bridge is balanced. When the balance has been reached, the unknown resistance can be determined from the ratio of the known resistances.


Related Questions

  1. Meter Bridge or Slide Wire Bridge is a practical form of?
  2. Can you find very high resistance accurately with the help of a Metre bridge?
  3. Why Carey Foster Bridge Is So Sensitive?
  4. Meter bridge works on the principle of?
  5. Why is Wheatstone's bridge more accurate?
  6. Why should we get the null point in the middle of the Metre bridge wire?
  7. How do you solve an unbalanced bridge?
  8. What Is Null Voltage?

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CBSE CLASS XII Related Questions

  • 1.
    This ‘average velocity’ is found be few mm/s for currents in range of a few amperes. How then is current established almost the instant a circuit is closed ?


      • 2.
        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?

          • \( (M_x - M_z)<M_y \)
          • \( (M_x - M_y)<M_z \)
          • \( M_x>(M_y + M_z) \)
          • \( M_x<(M_y + M_z) \)

        • 3.
          Derive an expression for the capacitance of a parallel plate capacitor of plate area A and plate separation d with air present between the plates.


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

              • 5.
                With the help of a labelled diagram, explain the principle, construction and working of an a.c. generator.


                  • 6.
                    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.

                      CBSE CLASS XII Previous Year Papers

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