# Energy in Circuits: The power lost to joule heating.

1. Mar 14, 2011

### BillJ3986

1. The problem statement, all variables and given/known data
The aluminum cable of a high-voltage transmission line carries a current 600A. The cable is 60km long, and it has a diameter of 2.5 cm. What is the power lost to Joule heating in this cable?

2. Relevant equations
Should I use the equation V=1/(4piEo)integral(dq/r) to find the potential? And in saying that I also need to find the charge in order to find the potential difference? Do I have to use Gauss's Law to find the charge?

3. The attempt at a solution
I know that the equation to find the power lost to joule heating is P=I^2R
in order to find the resistance, I solved solved for the potential difference using V=1/(4piEo)(q/r), I assumed that since the cable is aluminum that the Q= 1.6x10^-19C. my answer for potential difference is 1.2x10^-7 which I know is wrong.
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

2. Mar 14, 2011

### BillJ3986

I already answered the question. I had to look up resistivity for aluminum since the cable is made up of aluminum, and use the equation R=P(L/A). After finding the resistance. I was able to find out the power lost to Joule heating by using P=I^2(R). P=600^2(3.42)= 1.2X10^6W.