# Electric potential of a wire

1. Mar 12, 2009

### mjolnir80

1. The problem statement, all variables and given/known data
the wire in the image below has a linear charge density $$\lambda$$ . what is the electric potential at the center of the semicircle?
http://img18.imageshack.us/img18/5139/physicsproblem.jpg [Broken]

2. Relevant equations

3. The attempt at a solution
i know that the potential from the semi circle is V=KQ/R
but im having a little trouble figuring out how to calculate the potential from the other 2R pieces of wire.
can someone help me out here :)

Last edited by a moderator: May 4, 2017
2. Mar 13, 2009

### rl.bhat

Consider a small element dx at a distance x from the center P on either 2R piece. Charge on this piece is lambda*dx. Potential due to this piece dV = K*lambda*dx/( R + x ). To find the potential due one piece find the integration between the limits x = R to x = (2R + R). Then double it to get the total potential due to two straight pieces.

Last edited: Mar 13, 2009
3. Mar 13, 2009

### mjolnir80

thanks allot for the help