# Homework Help: Electric Currents and Resistance

1. Mar 27, 2004

### phystudent

A high voltage transmission line with a resistance of 0.06 ohms/km carries a current of 1337A. The line is at a potential of 500kV at the power station and carries the current to a city lovated 191km from the power station.
What is teh power loss due to resistance in the line? Answer in units of MW.

I know the formulas, but don't know how to start it or what the potential means.

2. Mar 27, 2004

### Integral

Staff Emeritus
First find the resistance of the line. You have all the information you need.

The potential is the voltage, use that with Ohms law to find the current.

Apply the same power equation as in the last problem.

3. Mar 27, 2004

### phystudent

OK, this is what I have done so far.

I used the .06 ohms/km and multiplied it bye 191km, to get the resistance. I also found the original power by multiplying the 1337A by the 500000V. So...I have 11.46 ohms of resistance and the original power is 6.685e8. Now I think I should plug the 11.46 ohms and the 1337A into the P = I^2 R formula. Any corrections?

4. Mar 27, 2004

### Integral

Staff Emeritus
That sounds good to me.

5. Mar 27, 2004

### phystudent

It's not working... the online homework service said it was wrong. I took the original number and the end number and subtracted them, then converted to MW and got 648.01, but that is not right apparently. Any help?

6. Mar 28, 2004

### Chen

How did you get to 648.01MW? I get 20.5MW using RI^2. Are you sure you are using the right values?

7. Mar 28, 2004

### phystudent

Thanks for the help but the homework is passed due, I tried it again and got 20.5MW