Calculation of Electric field Density(easy question, please help!!) 1. The problem statement, all variables and given/known data Problem : There is a 1C point charge on (0,1) positive y axis, and a 2C point charge on (0,-1) negative y axis. find the location where the electric field intensity is zero. 2. Relevant equations E = Q/4*PI*e*r^2 3. The attempt at a solution It's so simple!!! The answer is (0,3-2*(2^1/2)), or approximately, (0,0.2). This is actually an exam question. I am so darn sure that the answer is (0,0.2) and so does 90% of the students in class, but the professor keeps on saying he's 100% sure it's on the negative y axis (0,-0.2). How could he be so stubborn when 90% of the student in his class come up to him with the right answer? Honestly, I don't really understand how he became a professor... Anyway, this is very important for me because my grade would go one level down if I get this question wrong, and the professor tells us to bring sometime good enough to persuade him. I was searching for ages for something like an electric field calculator, but all I can find is java applets that only show the electric field lines, not the results in numbers. I know that the lines are sufficient enough to make someone believe that the E is zero at (0,0.2) but this professor just won't listen, so I might have to bring him a program with numerical calculation results. Do you have any suggestions for this? It doesn't have to be a program, but anything strong enough to make the man admit that he was wrong and accept the truth(i.e. a similar exercise example in a well known school textbook would be nice). Please help!!!