# Homework Help: Electric Potential Energy of a Rod

1. Feb 14, 2010

### SpringPhysics

1. The problem statement, all variables and given/known data
There is a thin rod of
length L that carries a uniform charge per unit
length $$\lambda$$. Starting from the expression for the
potential of a point charge, derive an expression
for the electric potential V (y) at a distance y
away from the centre of the rod on the axis (y) of
the rod. Assume y > L/2.

Use this result to derive the y-component of
the electric field, Ey, along the axis of the rod,
for y > L/2.

2. Relevant equations
V(r) = Q/4$$\pi$$$$\epsilon$$r

$$\Delta$$V = - $$\int$$E$$\cdot$$ds

3. The attempt at a solution
I thought that the electric potential would be unchanged since the electric field is perpendicular to the displacement...

Or is this acceptable because the wire is not infinite?

Last edited: Feb 14, 2010