Question 252: Current Electricity

Question

An electrical power line, having a total
resistance of 2 $$\Omega $$, delivers 1 kW at 220 V. The
efficiency of the transmission line is
approximately :

Accepted Answer

We know, $$\eta  = {{{P_{out}}} \over {\left( {{P_{out}} + {P_{loss}}} ight)}} 	imes 100$$
Given, P= $$vi = {10^3}$$
$$ 	herefore $$ $$i = {{1000} \over {220}}$$ = $${{50} \over {11}}$$ A
Power $$loss = {i^2}R = {\left( {{{50} \over {11}}} ight)^2} 	imes 2$$
$$ 	herefore $$ efficiency $$ = {{1000} \over {1000 + {i^2}R}} 	imes 100 = 96\% $$

Answer

85%

Answer

96%

Answer

72%

Answer

91%

Current Electricity

An electrical power line, having a total resistance of 2 $\Omega $, delivers 1 kW at 220 V. The efficiency of the transmission line is approximately :

Choose the correct answer: