Question

Two cities are 150 km 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 0.5Ω. 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

Hint: At first find the total resistance of the wire by calculating the resistance per km with total kilometers, then calculate the voltage drop by calculating voltage per km loss and total kilometers, then find the power loss.

Complete step by step answer:
Total Resistance of the wire is,
$R=(0.5\Omega /km)\times (150km)=75\Omega $
Total voltage drop is,
$=(8V/km)\times (150km)=1200V$
Therefore the Power loss is,
$=\dfrac{{{(\Delta V)}^{2}}}{R}=\dfrac{{{(1200)}^{2}}}{75}W$
=19.2 kW
Option B is the correct option.

Additional Information:
The difference between two points where the potential is different, is known as potential difference.
In reality current travels lower to higher potential.
The opposition to a current flow is known as resistance.
Rate per unit time is known as electric power.
Conductor is an object or a material which allows flows of charge in one or more directions.
An inductor, is a passive two-terminal electrical component that stores energy in a magnetic field when current flows through it. It is also called a coil, choke, or reactor, it. It is typically core wound by insulator wire.

Note: The resistance given is average resistance which is not the total resistance offered by the circuit we have to calculate it.
The voltage drop given is also per kilometer we have to calculate the total voltage drop.
Power loss is calculated by total voltage square divided by total resistance offered.