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 Electricity and Magnetism Electricity and Magnetism Physics Help Forum Apr 15th 2017, 02:35 AM #1 Junior Member   Join Date: Apr 2017 Posts: 1 Electrical Potential Difference Problem Hi, I was wondering if you guys can help me solve this homework problem my Professor assigned to me. Also, He made it clear that I cannot use the solution the textbook solution manual uses because its a graduate level technique. They use something called "Stanley number", in which you let S= 4 x pi x K and by doing so allowing the equipotential surfaces to be equi-Stanley surfaces. One of the pictures attached is the problem, and the other one is my attempt at the problem. I was wondering if my attempt on the problem is on right path? Like if there's another simplier way of doing it. Also is too similar to the way the TB solution manual solves it ( in one of the pictures)? So my thought process was using one of the formulas for Potential Difference (V) of two point charges. Then using the distance formula for for r1 and r2. Then since it's given that V=0, i can set the point charges equal to each other to solve for X which in this case would be Xc Last edited by Nitebreaker; Apr 15th 2017 at 02:39 AM.   Apr 15th 2017, 03:38 AM #2 Senior Member   Join Date: Apr 2015 Location: Somerset, England Posts: 1,035 Well you are almost along the right lines but I would suggest adding some reasons/justification for your equations. To start with the potential field due to any number of charges is the sum of the potential fields of each charge individually, without any of the others present. This is known as the principle of superposition and is appears in many aprts of Physics. So that is the justification for your first equation but it needs a little tweaking. The individual potentials form (two sets of) concentric circles about q1 and q2. But the two sets do not have the same centres. So a simple exercise in coordinate geometry supplies the equations for each set of circles and you just need to add them together to the the overal equations of the potential field. The equation of a circle, centered at the origin is of course x^2 + y^2 = A constant The equation for q2 is (x+d)^2 + y^2 = a constant where d is the position of q2 along the x axis.  Tags difference, electrical, potential, problem Thread Tools Show Printable Version Email this Page Display Modes Linear Mode Switch to Hybrid Mode Switch to Threaded Mode Similar Physics Forum Discussions Thread Thread Starter Forum Replies Last Post nakenjiex Electricity and Magnetism 1 Feb 25th 2015 12:32 PM rcmango Electricity and Magnetism 5 Jul 15th 2011 10:18 AM missyc8 Electricity and Magnetism 3 Sep 30th 2009 09:16 AM blush Advanced Electricity and Magnetism 1 May 24th 2009 09:04 AM Mr Rayon Electricity and Magnetism 1 May 1st 2009 07:55 AM