Current Electricity and Electrical InstrumentMedium
Question
An electric power line having total resistance of $2\Omega$, delivers 1 kW of power of 250 V . The percentage efficiency of transmission line is $\_\_\_\_$。
Options
A.96.9
B.86.5
C.100
D.92.5
Solution
$P_{\text{out~}} = 1000\text{ }W$
$${P = VI }{1000 = 250 \times I }{I = 4\text{ }A }{P_{\text{loss~}} = I^{2}R = (4)^{2} \times 2 = 3200 }{P_{\text{net~}} = 1000 + 32 = 103200 }{\eta = \left( \frac{P_{\text{out~}}}{P_{\text{net~}}} \right) \times 100 = \frac{1000}{1032} \times 100 = 96.9\%}$$
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