(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

the electric potential of some configuration of charge is given by the expression:

V(r)= (Ae^(-pr))/(r)

where A and p are constants. Find the E-field E(r), the charge density rho(r) and total charge Q. The answer for rho is given in book as:

epsilon-not * A * ((1/r)4* pi* dirac delta^3 (r) - p^(2) e^(-p*r))

(The stuff inside parentheses is all divided by r

2. Relevant equations

-del V= E; del dot E = rho/epsilon-not ;

3. The attempt at a solution

I the took gradient of V using sperical coordinates using the formula

-del V= E

to obtain E.

Then I used the formula

del dot E = rho/epsilon-not

to find rho. I am not getting the same rho as in the book. I dont understand why the dirac delta function is in the answer. Do you have to perform an integration or am I taking a wrong apprach all together?

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# Homework Help: Electromagnetism Finding E-fields

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