How Do You Calculate the Electric Potential Below a Charged Wire?

[kevinf]

Homework Statement

One conductor of an overhead electric transmission line is a long aluminum wire 2.40 cm in radius. Suppose that at a particular moment it carries charge per length 1.40 µC/m and is at potential 350 kV. Find the potential 10.9 m below the wire. Ignore the other conductors of the transmission line and assume the electric field is everywhere purely radial.

Homework Equations

i think for this problem you would use the integral of dq/r right?

The Attempt at a Solution

i am not sure how to do this problem. it tells me that it is 10.9 m below the line but it doesn't say where under the wire. would i some how use the 350 kV and get the location under the wire? also i am not sure how the radius of the wire comes in the equation. the ones that i have been doing are rods that have no radius so i am not really sure how to do this problem

 

[Redbelly98]

Does your textbook or course notes discuss the electric field of a line charge? That would be relevant here.

 

[kevinf]

yes but the example that they gave is much simpler and it is just a rod with no radius

 

[Redbelly98]

Okay, good.

The same expression for electric field will be true here, as long as:

• The distance is taken to the center axis of the transmission line
• The distance is larger than the radius of the transmission line

(Inside the transmission line, E=0 as for any conductor)

 

[kevinf]

oh sorry this is asking for electrical potential though

 

[Redbelly98]

Potential and electric field are related via doing an integral.