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Can you clarify this step (charge density and integrals).

  1. Sep 9, 2011 #1
    Hi, if you have the book: Physics for Scientists and Engineers 8E, Serway Jewett

    On page 675 (Chapter 23), Example 23.8 there is a step taken during the integration I don't understand:

    How do you go from "2r dr" in the numerator to d(r^2)? If there is info or link to the property of integrals which explains this, I would appreciate seeing it. Thank you.
     
  2. jcsd
  3. Sep 9, 2011 #2
    hhhmmm...well, what do you get when you take the derivative or r2 ? In other words, what's d(r2)? is it 2rdr?
     
  4. Sep 10, 2011 #3
    Hi.

    d(r^2)/dr = 2r is fundamental formula of derivative.

    multiplying dr on both sides,

    d(r^2) = 2r dr

    Regards
     
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