Physics - Current Electricity Question with Solution | TestHub

Distance between the two cities, $150 \mathrm{km}$.

Voltage drop per kilometre is $8 \mathrm{V} {\mathrm{km}}^{-1}$.

Resistance per kilometre $0.5 \mathrm{\Omega } {\mathrm{km}}^{-1}$

Total voltage drop will be,
$V_{drop}=150 \mathrm{km}\times 8 \mathrm{V} {\mathrm{km}}^{-1}=1200 \mathrm{V}$

Total resistance of wire, 
$R=0.5 \mathrm{\Omega } {\mathrm{km}}^{-1}\times 150 \mathrm{km}=75 \mathrm{\Omega }$

Therefore, the power loss will be, $P=\frac{V^2}{R}=\frac{{\left(150\times 8\right)}^2}{0.5\times 150}=19.2 \mathrm{kW}$