Calculating PD between +q and -q Charges at Points A & B

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The discussion focuses on calculating the potential difference between two charges, +q and -q, located at points A and B, respectively, separated by distance R. The user attempts to solve the problem using two methods: integrating the electric field and directly calculating the potentials at both points. Both methods yield an absurd result of 2kq/0, indicating a potential error in the calculations. The user expresses confusion about the integration process, questioning the necessity of integrating when only two charges are present. Assistance is requested to clarify the integration limits and the overall approach to finding the correct potential difference.
Highwaydude
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Homework Statement



Charges +q and -q at points A and B respectively separated by distance R. Required to calculate the potential difference between these 2 points.

Homework Equations



I want to do in two ways.. i.e once by integrating the electric field and the other by directly finding the potential at the two points and then subtract them to have the difference

The Attempt at a Solution


Both of my trials have yielded a 2kq/0 which is a bit absurd...
I do like this>
Vb -Va= - ((integration sign)kq/r^2 dr-(int.sign)kq/(R-r)^2 dr)
between the limits 0 to R.. It yields 2kq/0(wth!)-2kq/R...
So yeah.. I need help. Oh and K = 1/4pi e0
 
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please check if you are putting the limit right
 
also i don't knw why r u integrating when only two charges are present
 
i am calculating the net electring field... i guess the two kq/0's cancel out one being negative, but its just not coming. i mean bot hare coming out to be positive...
 
Heres the working... sorry, i can't find my mobile phone data cable.. had to do it in paint... http://hostmypicture.com/images/untitlete.png
 
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