# Meaning of a sentence concerning the electric field inside its source charge

Could someone please explain to me the meaning of this sentence in bold type ? :

" In the neighborhood of a true point charge the electric field grows infinite like $\frac{1}{r^2}$ as we approach the point. I t makes no sense to talk about the field at the point charge. As our ultimate physical sources of field are not, we believe, infinite concentrations of charge in zero volume but instead finite structures, we simply ignore the mathematical singularities implied by our point-charge language and $\textbf{rule out of bounds the interior of our elementary sources}$ ."

Source : Electricity and Magnetism (Purcell) p21 .

• This is saying that there is no mathematical description for what the electric field is inside of a point charge. – David White Aug 17 '18 at 20:36

## 1 Answer

I think it just means you can't calculate the field 'inside' the point charge by using the 1/r^2 relation. By 'elementary sources' it is just talking about electrons, protons etc.