- #1

mysubs

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I've been searching this today but I am a bit lost now. I've encountered two forms of Gauss law in its differential form, Poisson equation :

del

^{2}V(r) = -p(r)/e

del

^{2}V(r) = -4*pi*p(r)/e

where V:e.potential, p:charge density, e:permivity

Now, what's the difference between these two /or/ where does the (4pi) in the second one comes from?

Mathematically they are not equivalent, but they are presented as such. Any opinions?