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Homework Help: Divergence homework problem help

  1. Jul 19, 2014 #1
    1. The problem statement, all variables and given/known data

    How divergence of r (cap)/ |r|^2 is equal to zero?

    2. Relevant equations

    r(cap)= x(cap)+y(cap)+z(cap)

    |r|^2 as x^2+y^2+z^2

    3. The attempt at a solution

    I tried the problem and end up with with a different solution I took r(cap)= x(cap)+y(cap)+z(cap)
    |r|^2 as x^2+y^2+z^2. Tell me where i went wrong?

    where r(cap) is unit vector of r vector
    |r|^2 is the square of modulus of r
  2. jcsd
  3. Jul 19, 2014 #2
    Could you please provide the calculation that lead you to the wrong answer? It is hard to pinpoint where you went wrong otherwise.
  4. Jul 19, 2014 #3


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    You didn't differentiate correctly. Show your work.
  5. Jul 19, 2014 #4
    Here's my attempt to the problem

    Attached Files:

  6. Jul 20, 2014 #5
    Well ##\mathbf{\hat r} = \mathbf{\hat x} + \mathbf{\hat y} + \mathbf{\hat z}## seems false. You have ##\mathbf{r} = (x,y,z)##. Work from there.
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