A) \[3\,\,\Omega \]
B) \[4\,\,\Omega \]
C) \[5\,\,\Omega \]
D) \[6\,\,\Omega \]
Correct Answer: D
Solution :
Resultant of \[2\] and \[8\] in parallel (ratio\[=4\]) \[=\frac{4}{5}\times 2=\frac{8}{5}=1\cdot 6\] Resultant of \[6\] and \[4\] in parallel (ratio\[=1\cdot 5\]) \[=\frac{1.5}{1.6}=0.6\times 4=2.4\] As shown below, these two are in series. The equivalent circuit now consists of \[3,\,\,4,\,\,r\] in parallel. \[\frac{1}{3}+\frac{1}{4}+\frac{1}{r}=\frac{3}{4}\] or \[\frac{1}{r}=\frac{3}{3}-\frac{1}{4}-\frac{1}{3}=\frac{2}{4}-\frac{1}{3}=\frac{1}{2}-\frac{1}{3}=\frac{1}{6}\] So, \[r=6\]You need to login to perform this action.
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