A) 2
B) 3
C) 6
D) 9
Correct Answer: C
Solution :
Let resistance r Q, be shunted with resistance S, so that bridge gets balanced. If S is the equivalent resistance of S and r, In balanced position \[\frac{P}{Q}=\frac{R}{S'}\] \[\therefore \,\,\,\,\,\,\,\,\,\,\frac{2}{z},\,\,\frac{2}{5}\,\,\Rightarrow \,\,\,S'=2\,\Omega \] Now, \[\frac{1}{S'}=\frac{1}{S}+\frac{1}{r}\] \[\Rightarrow \,\,\,\,\,\,\frac{1}{r}=\frac{1}{S}-\frac{1}{S}=\frac{1}{2}-\frac{1}{3}=\frac{3-2}{6}\] \[\frac{1}{r}=\frac{1}{6}\,\,\,\Rightarrow \,\,r=6\,\Omega \,\]You need to login to perform this action.
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