To Find Value of Unknown Resistance by Wheatstone bridge

Answer:

To find the unknown resistance,

four resistors are connected in the four arms of the Wheatstone bridge as shown in the figure.

Here R₁ and R₃ are the known resistances, R₂ is the variable resistance, and R_x is the unknown resistance.

The galvanometer is connected between the terminals of D and B to determine the null or balanced condition of the bridge.

We have to vary the variable resistance until the null condition is obtained, at this instant the galvanometer reads zero.

During the null condition, the product of resistances in the opposite arms of the bridge is equal.

⇒R₁R_x=R₂R₃

⇒R_x/R₂=R₃/R₁

⇒R_x=R₃R₁/R₂

In this way, we can find the unknown resistance by using the Wheatstone bridge.

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