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Two point charges

  1. Jan 26, 2013 #1
    Greetings fellow physics adorers/ mathematicians,

    I was wondering if someone could help me with my posted problem. All the necessary details from the template are included in the screenshot on the right.
     

    Attached Files:

  2. jcsd
  3. Jan 26, 2013 #2

    gneill

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    Staff: Mentor

    From the second attachment (the one on the right) it looks as though you need only cross multiply and solve for x to finish.
     
  4. Jan 26, 2013 #3
    I don't know how to do so mathematically...
     
  5. Jan 26, 2013 #4

    rude man

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    Your starting formula is wrong.

    Draw a picture of the two charges along a line, then equate Coulomb attraction of a unit (positive) test charge to qB to repulsion of that test charge from qA.

    Hint: the zero-field point might be between qA and qB, or it might not ...
     
  6. Jan 26, 2013 #5
    Coulomb's law is not used. My professor said to only use the E=k[q]/rsquared formula...
     
  7. Jan 26, 2013 #6
    I know that the order of the point charges goes as followed


    qb -------------------qa--------------------P
     
  8. Jan 26, 2013 #7

    rude man

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    Never mind, you called x the distance from p to qB and d the distance between qA and qB, so what you wrote is fine.
     
  9. Jan 26, 2013 #8

    gneill

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    Really? :confused:

    If ##\frac{a}{b} = \frac{c}{d}## then ##a \cdot d = b \cdot c##

    You've never seen this?
     
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