A) 10W
B) 5W
C) 20W
D) None of these
Correct Answer: C
Solution :
\[\frac{H}{t}=P=\frac{{{V}^{2}}}{R}\Rightarrow P\propto \frac{1}{R}\] also \[R\propto \frac{l}{A}\propto \frac{{{l}^{2}}\rho }{A.l\rho }\] Þ \[R\propto \frac{{{l}^{2}}}{m}\] Þ \[R\propto {{l}^{2}}\] (for same mass) So \[\frac{{{P}_{A}}}{{{P}_{B}}}=\frac{l_{B}^{2}}{l_{A}^{2}}=\frac{4}{1}\Rightarrow {{P}_{A}}=20\,W\]
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