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Homework Help: Electric field of a disk & u-substitution

  1. May 25, 2016 #1
    1. The problem statement, all variables and given/known data
    Calculate the electric field at point P (refer to visual): Capture.JPG

    2. Relevant equations
    I follow everything - except how the limits of integration for the u-integral ( Capture1.JPG ) are arrived at?

    3. The attempt at a solution
    u=x2 is the smallest value u can have, and u=x2+R2 is the greatest value u can have?
     
  2. jcsd
  3. May 25, 2016 #2

    TSny

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    The lower limit of the u integration should correspond to the lower limit of the r integration (r = 0). So, the lower limit of the u integration is the value of u when r = 0. Similarly for the upper limit.
     
  4. May 25, 2016 #3
    Very helpful - thank you!
     
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