What is the Electric Field in a Non-Uniformly Charged Spherical Volume?

  • #1
mateomy
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I have an exam on Monday in my E&M class. I've been doing the homework, etc etc. My prof. even has a link on his website that has old exams that we can use to study from. The exam I am practicing off of has the questions, a (sketchy) calculation, and an answer. This question has been driving me and my classmates NUTS! Nobody can solve it! I can't make sense of his calculations, can somebody please tell me I am not crazy…or, better yet…show me what I am not seeing. Thanks.

ScreenShot2011-09-17at114319PM.png


That weird looking thing at the top that looks like R**(2.3) is supposed to be the radius to the power of 2.3. Yeah, I don't get it either, but that's what my prof. told me.

The answer is in parenthesis.

Is there something wrong with the calculations?

Why can't I figure this out??
 
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  • #2
Rewriting this, in case you don't understand it: you have a spherical volume filled with distributed static charge. It's not uniformly distributed, it gets more dense the farther you move away from the centre. The charge density in the sphere is a function of distance from the centre=(5.5*10-15)*r2.3

I've forgotten how to solve these. :redface: I guess it's going to involve an integral.
 
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