
#1
Sep3010, 09:59 AM

P: 211

1. The problem statement, all variables and given/known data
I'm looking at Y.K.Lim's Problems and solutions in Electromagnetism and there's one thing that's confusing me: 2. Relevant equations Where does the square in r comes from? When in the beginning it says that the electric field is: [tex]E=A\frac{e^{br}}{r}e_r[/tex] not[tex]E=A\frac{e^{br}}{r^2}e_r[/tex] What am I missing? And what should [tex]e_r[/tex] stand for? Charge? 



#2
Sep3010, 10:52 AM

P: 802

This Efield is not due to a single charge. It is due to a distribution of charges, so it needs not be proportional to r^2. For example, a uniformly charged plane produces uniform Efield on each side of the plane, obviously not proportional to distance^2, correct?
[tex]e_r[/tex] is the unit radius vector. 



#3
Sep3010, 11:06 AM

P: 211

Ok it needs not be proportional to r^2, but why did he put it then? When taking the divergence of the field?




#4
Sep3010, 11:13 AM

P: 802

Electrostatic problem
Oh I see. Then it seems to me that it's a typo




#5
Sep3010, 12:40 PM

P: 211

Oh, I thought it's something new I didn't know XD



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