(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

A power station delivers 440 kW of power through 3 ohm lines. How much power is wasted if it is delievered at 12000v?

2. Relevant equations

v=IR

P=I^2R

P=IV

3. The attempt at a solution

I believe you are supposed to solve it like this but I do not understand why:

I=P/V = 440000/12000=36.67 A

P lost =I^2R=(36.67)^2 (3) = 4033 W

But my gut instict tells me to do this which I believe is wrong from what I've read:

P=V^2/R = (12000)^2/3 = 4.8 x 10^7 W

P lost = P - Pused = (4.8 x 10^7 - 440000) =4.756 x 10^7W

I think I'm getting confused with what "V" is. I keep googling it and all I can tell is that I don't understand the different between voltage and voltage drop. I'm not clear what either is. Could anyone please explain?

Why does P=I^2R give you the power lost rather than the original power (440 kW) or the power used?

**Physics Forums - The Fusion of Science and Community**

# Difference between voltage and voltage drop?

Know someone interested in this topic? Share a link to this question via email,
Google+,
Twitter, or
Facebook

Have something to add?

- Similar discussions for: Difference between voltage and voltage drop?

Loading...

**Physics Forums - The Fusion of Science and Community**