# Net PE in ions

1. Jul 23, 2011

### f3nan

The general expression for calculating net potential energy in ion is:

PE (r) = A r^m + B r^n

where A & B are proportionality constants.

What exactly are these constants??
Could anyone point me to correct resources??
I'm new at this forum and very interested in learning physics.?

2. Jul 24, 2011

### FireStorm000

I don't know if I'm entirely clear on what you're asking; make sure you're proofreading your posts and being as descriptive as possible. Taking my best guess at your question, the equation for electrostatic attraction or repulsion between two charged particles is:
(Sorry if you don't know calculus)
F=kE*q1*q2/r2
where q is charge, kE is the proportionality constant(permeability of free space/4pi), and r is distance.
If we assume the particle to have 0 potential energy at infinite distance, (defining it as the zero level), and the definition of work we can then create an expression describing the work done moving a particle of charge q from infinity to R.
W=$\int$F dr (from infinity to R)
Substituting and integrating gives:
W=[-1*kE*q1*q2/r](inf to R)
W=-1*kE*q1*q2/R
$\Delta$PE=PEF-PEI
W=kE*q1*q2(1/RF-1/RI)