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Thursday, 28 November 2013

Q.No.13.9: - What is Wheatstone bridge? How it be used to determine an unknown resistance?

Q.No.13.9: - What is Wheatstone bridge? How it be used to determine an unknown resistance?
Ans: - Wheatstone bridge is used to determine unknown resistance of a wire. The circuit is consists of four resistances R1, R2, R3, R4 connected in such a way as to form a loop or mesh ABCDA. A battery of emf E is connected between points A and C. A galvanometer of resistance Rg is connected between the points B and D.
          When the bridge is balanced, it satisfied the following relation
                                        R1/R2      =       R3/R4
Or,                                   R4           =        R2.R3/R1
If the value of R1, R2, and R3 are known then R4 can be calculated. The galvanometer should not show any deflection by adjusting the potential between terminals B and D. (Sorry for Diagram. Pleas concert with Text Book for diagram.)

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