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Question

Physics Question on Current electricity

Four resistors A,B,CA, B, C and DD form a Wheatstones bridge. The bridge is balanced, when C=100ΩC=100 \Omega. If AA and BB are interchanged, the bridge balances for C=121ΩC=121 \Omega. The value of DD is

A

10Ω10 \Omega

B

100Ω100 \Omega

C

110Ω110 \Omega

D

120Ω120 \Omega

Answer

110Ω110 \Omega

Explanation

Solution

Balancing condition of bridge balance AB=100x\frac{A}{B}=\frac{100}{x} BA=121x\frac{B}{A}=\frac{121}{x} 100x=x121\therefore \frac{100}{x} =\frac{x}{121} x2=12100x^{2} =12100 x=110Ωx =110 \,\Omega