# Find its radius and location of its Centre [closed]

Two fixed charges $$-2Q$$ and $$Q$$ are located at the points with coordinates $$(-3a,0)$$ and $$(+3a,0)$$ respectively in the x-y plane. Show that all the points in the x-y plane where the electric potential due to the two charges is 0, lie on a circle. Find its radius and location of its Centre.

## closed as off-topic by John Rennie, Bill N, GiorgioP, Kyle Kanos, HDE 226868Apr 29 at 19:29

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• Welcome to Physics.SE! This question will likely be closed as the policy of the site of not to answer "do-my-homework" type questions. I would recommend resubmitting your question showing your attempt at a solution and stating clearly what physics concepts you are struggling with. – Josh Hoffmann Apr 27 at 14:30
• Hi and welcome to the Physics SE! Please note that we don't answer homework or worked example type questions. Please see this page in the site help for more on what topics you can ask about here. – John Rennie Apr 27 at 14:37

Let's understand the problem from very basics. We all know Coulomb's law which states $$| F| = \frac {kqq'}{r²}$$ now we can see that in the following problem you are required to find the locus of all the neutral points in the x-y plane. So let's start by calculating the force due to the charges at point $$(x,y)$$. Before this let's introduce the vector form of coulomb's law which says $$F̅ = \frac {kqq'}{r³} r̂$$ hint :- you have to write the force expression at a generic point $$(x,y)$$ and then equate its magnitude to zero this would generate required locus .