A) 2.5 \[\Omega \]
B) 7.5 \[\Omega \]
C) 10 \[\Omega \]
D) 12.5 \[\Omega \]
Correct Answer: B
Solution :
Key Idea: The given circuit is a balanced Wheatstone bridge. The equivalent circuit is shown below: In the given circuit, the ratio of resistances in the opposite arms is same \[\frac{P}{Q}=\frac{10}{10}=\frac{1}{1}\] \[\frac{R}{S}=\frac{5}{5}=\frac{1}{1}\] Hence, bridge is balanced. The given circuit now reduces to Here, \[10\,\Omega \]and\[5\,\Omega \]resistors are in series, therefore Now, the two \[15\,\Omega \]resistors are connected in parallel, hence equivalent resistance is \[R=\frac{15\times 15}{15+15}=\frac{225}{30}=7.5\,\Omega \]You need to login to perform this action.
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