Calculate Power & Fraction Lost in High-Voltage Transmission Line

[goWlfpack]

Homework Statement

A high-voltage transmission line with a resistance of 0.28 /km carries a current of 990 A. The line is at a potential of 740 kV at the power station and carries the current to a city located 162 km from the station.
(a) What is the power loss due to resistance in the line?
W

(b) What fraction of the transmitted power does this loss represent?
%

Homework Equations

Power= change in V^2/R

where v is potential difference and R is resistance

Power = I^2*R

where I is current

The Attempt at a Solution

I got part a correct. I used the equation p=I^2*R and got 44457336
I can't figure out how to get the second part though
I tried using p=v^2/R with 740,000 as the V and .28(162) as the R to no avail

any suggestions?

 

[Gear300]

If you notice, V/R does not give a current of 990 A. The concept gets a little more complicated with a transformer. I*V (990A*740kV) is the provided power. I^2*R is the power lost to resistance.

 

[tiny-tim]

Hi goWlfpack!

any suggestions?

p = IV?

 

[goWlfpack]

got it! thanks guys! :)