A) 36 W
B) 18 W
C) 27 W
D) 54 W
Correct Answer: C
Solution :
Key Idea: When resistors are connected in parallel potential difference across them is same. In this circuit combination two resistors are connected in parallel, hence \[\frac{1}{R'}=\frac{1}{R}+\frac{1}{R}=\frac{2}{R}\] \[\Rightarrow \] \[R'=\frac{R}{2}\] Now, these two resistors \[\left( \frac{R}{2}and\,R \right)\]are in series, hence equivalent resistance is \[{{R}^{'\,'}}=\frac{R}{2}+R=\frac{3R}{2}\] Power across single resistor is 18 W i.e., \[p={{i}^{2}}R=18\] ?(i) Power across combination obtained is \[P'={{i}^{2}}.\frac{3R}{2}\] ?(ii) Dividing Eq. (i) by Eq. (ii), we get \[\frac{{{i}^{2}}R}{{{i}^{2}}\frac{3R}{2}}=\frac{18}{P'}\] \[\Rightarrow \] \[P'=\frac{3}{2}\times 18=27\,W\]You need to login to perform this action.
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