### Step 1: Understand the geometry

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Pick a point P for evaluation of **E**.
The only variable which matters is R, the distance from the line of charge.
There is no angular dependence because the line is cylindrically symmetric,
*i.e.* it does not matter at which angle about the line you view it.
There is no axial dependence because the line of charge is infinitely long,
*i.e.* there is no preferred position along the line.
The infinite line of charge is certainly a physically-impossible situation
to set up (infinite amount of charge)
but one whose consideration is useful in interpreting
*finite* distributions,
*e.g.* checking the limiting behavior of solutions.

"http://www.physics.udel.edu/~watson/phys208/lineofcharge1.html"

Last updated Sept. 24, 1997.

Copyright George Watson, Univ. of Delaware, 1997.