- #1
Slusho
- 17
- 0
Homework Statement
Find the total charge Q given the charge density ρ(r)=ε0A(4πδ3(r)-π2e-λr/r
The Attempt at a Solution
I know the solution's steps start with: Q=∫ρdr=ε0A(4π∫δ3(r)dr-λ2∫e-λr(4πr2)/rdr)
What I don't understand is where that 4πr at the end comes from. That last step is only distributing the integrals except for putting that 4πr in there, so it seems to come from nowhere.