Question:
An electrical power line, having a total resistance of $2 \Omega$, delivers $1 \mathrm{~kW}$ at $220 \mathrm{~V}$. The efficiency of the transmission line is approximately:
Correct Option: 4,
Solution:
(2) Given : Power, $P=1 \mathrm{~kW}=1000 \mathrm{~W}$
$R=2 \Omega, V=220 \mathrm{~V}$
Current, $I=\frac{P}{V}=\frac{1000}{220}$
$P_{\text {loss }}=I^{2} R=\left(\frac{1000}{220}\right)^{2} \times 2$
$\therefore$ Efficiency $=\frac{1000}{1000+P_{\text {loss }}} \times 100=96 \%$
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