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Question: Answered & Verified by Expert
An electrical cable having a resistance of $0.2 \Omega$ delivers $10 \mathrm{kw}$ at $200 \mathrm{~V}$ D.C. to a factory. What is the efficiency of transmission?
PhysicsCurrent ElectricityWBJEEWBJEE 2009
Options:
  • A $65 \%$
  • B $75 \%$
  • C $85 \%$
  • D $95 \%$
Solution:
2178 Upvotes Verified Answer
The correct answer is: $95 \%$
$P=V I \Rightarrow I=\frac{10 \times 10^3}{200}=50 A$, Power loss $=(50)^2(0.2)=500 \mathrm{~W}$
Efficiency $=\frac{10000 \times 100}{10000+500}=95.23 \%$

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