- #1

leonne

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## Homework Statement

Well the problem is a electromagnetism problem: I need to find the charge density. Given

E= kr^3 r^

## Homework Equations

formula is gradient E=p/e0

## The Attempt at a Solution

They got the gradient of E to be 1/r^2 (d/dr) (r^2 Er) i have no idea how they did it i know gradient is d/dx+ d/dy+d/dz so idk how they got that from E

then they got Eo(1/r^2 (d/dr)(r^2(kr^3) ... answer p=5kEor^2

Is that just a formula for any spherical polar coordinate? 1/r^2 (d/dr) (r^2 Er) Professor said something about looking in the back of the front cover for this. I just have pdf of book and doesn't have back cover. So if it is a formula can you tell me the whole thing thanks