How does the magnetization of an atom change at its center?

[Lord33]

Homework Statement

We have coaxial cabel with radius R and R₀=3R filled with magnetic.Magnetization J(r)=(r³-R³)/(2R³)*I/(2*pi*r).What is the magnitization if r=0(center of atom)?And what a magnetization direction of atom?

Homework Equations

The Attempt at a Solution

I think what magnitization in center of atom = -inf , but it is wrong.

 

[mfb]

The formula for the magnetization works in a limited range (for r) only. Can you find that range?
You can modify the formula a bit to make it applicable at r=0.

 

[Lord33]

I understand what we must take radius of atom but how i can modified a formula if r<r_a?I find limit and get -inf it is wrong.I know that J=∑P/ΔV.

 

[mfb]

You don't need the radius of an atom.

Your formula has an I in it. What is that? A current, sure, but a current of what? Every cable in the universe? Which current exactly do you have to consider in that formula, and is it the same current for every place?