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Having trouble finding the potential between two positive point charges.

  1. Jan 29, 2013 #1
    1. The problem statement, all variables and given/known data



    How to find the potential between two positive point charges?

    I don't know where I'm going wrong.

    ==I am adding V_1 and V_2. converted mC to C, cm to m, correct value of k.

    V1= kq1 / r1
    v2= kq2/ r2.


    ==I am adding both of these, but I'm not getting the correct answer.

    ===Problem:

    A point charge of q1 = 2.37 µC is 44 cm from a charge of q2 =26.4 µC. Where is the electric field zero? What is the value of the potential there?
    ----------

    electric field is zero at 0.101m (correct answer).

    I have r1= .101m and r2= .44m - .101= .34m.

    I'm using the correct value of k.

    == The answer is given as 2.34 * 10^6 V.


    Can you help me find out where I'm doing wrong?
     
  2. jcsd
  3. Jan 29, 2013 #2

    haruspex

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    We cannot tell where you are going wrong if you do not post all your working.
     
  4. Jan 29, 2013 #3

    Edit: The potential at the point is equal to the sum of the two potentials of the two point charges.

    V= kq_1 / r_1 + kq_2 /r_2

    V= (9*10^9 Nm^2/C^2)* (2.37 * 10^-6 C)/ .101m + (9*10^9 Nm^2/C^2)*(26.4*10^-6 C) / .34m = 9.10*10^5 V.

    The correct answer is 2.34 *10^6 V.

    I don't know what I'm doing wrong.
     
  5. Jan 29, 2013 #4

    haruspex

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    I agree with your answer (almost: 9.11e5).
     
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