Hi guys, Suppose I have a point O in the centre of the square (of side length X), where the top 2 corners of the square carries a positive charge each and the bottom left corner a negative charge and the bottom right corner a positive charge, what would the magnitude and direction of the magnetic field strength at point O be? I figured that it would be towards M, but how do I find it's magnitude? The given answer is q/(pi)(Enot)(x^2). I don't realy understand why is the 4 missing? Thanks!