Calculating Power Loss in a High Voltage Transmission Line

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The discussion revolves around calculating power loss in a high voltage transmission line with given parameters: current of 1000 amps, voltage of 700,000 volts, and a resistance of 0.5 ohms per mile over 100 miles. The initial power is calculated as 700 million watts, while the power loss due to resistance is found to be 50 million watts using the formula P = I^2 * R. A misunderstanding arises regarding whether to calculate the total power transmitted or just the power dissipated by the wire. Participants clarify that the focus should be on the power lost, which is 50 million watts, not the difference from the total power. The conversation highlights the importance of accurately interpreting the problem statement.
SparkimusPrime
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A question surprisingly similar to this:

https://www.physicsforums.com/showthread.php?t=17219

I = 1000amp
V = 700,000volt
distance = 100miles
Resistence of the wire = .5 ohm / mile

The resistence of my line is 50 ohms, original power is 7e5 * 1e3 = 7e8 watts. Final power, due to P = (I^2) * R, is 1e3^2 * 50 = 5e7 watts

So finding the difference:

7e8 - 5e7 = 6.5e8

The answer given by the teacher is 50 MW (50e6 watts right?). A math error I'm sure, anyone see it?

Peter
 
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I am not sure why you are computing the difference.

The power lost by the line is

P=I2R

End of story, you do not even need to know the total power transmitted.
 
Maybe your teacher wants the power dissipated by the wire, and not the power that is left?

Beat me to it. :smile:
 
Yes sorry, read the problem wrong. Seems to be a common failing with this book, using obscure english to mask the real problem.

Thanks.

Peter
 

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