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Homework Help: Surface integration

  1. Aug 15, 2011 #1
    Please some one help me how to solve this problem
    integral-r^2 sin(theta) d(theta) d(phi)
     
  2. jcsd
  3. Aug 15, 2011 #2

    I like Serena

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    Hi skanda9051! :smile:

    What did you try?
    That would help me to know what I should explain to you.
     
  4. Aug 15, 2011 #3
    Well its magnetic flux E through a sphere of radius r and flux is given.
    integral E. da=integral 1/4pi Eo (q/r^2).(r^2 sin(theta) d(theta) d(phi) they have given answer as q/Eo:-). My doubt is since it is surface integral there should be 2 limits one with respect to theta and another with respect to phi:-). So how did they integrate with respect to phi
     
  5. Aug 16, 2011 #4

    I like Serena

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    Yes, there are limits wrt theta and another wrt to phi.
    This is be a double integral and not a single integral.
    The limits are defined by the definition of spherical coordinates, although you do not need them to integrate your expression.

    How would you integrate [itex]\int 5 d\phi[/itex]?
    And how would you integrate [itex]\int 5 \sin(\theta) d\theta[/itex]?

    Btw, in (these) spherical coordinates phi runs from 0 to 2pi, and theta runs from 0 to pi.
     
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