Question

Two cities are $150km$ apart. Electric power is sent from one city to another city through copper wires. The fall of potential per $km$ is $8$ volt and the average resistance per $km$ is $0.5\Omega$. The power loss in the wire is

• A. 19.2 W
• B. 19.2 kW
• C. 19.2 J
• D. 12.2 kW

Answer 1

Answer: (B)

Here, Distance between two cities $=150km$
Resistance of the wire, $R=\left(0.5\Omega k{m}^{-1}\right)(150km)$
$=75\Omega$
Voltage drop across the wire,
$V=\left(8Vk{m}^{-1}\right)(150km)=1200V$
Power loss in the wire is
$P=\frac{V^2}{R}=\frac{(1200V{)}^2}{75\Omega }19200W=19.2KW$