I made a typo. I meant, Biot- Savar Law( sorry ).1. The problem statement, all variables and given/known data A conductor in the shape of a square Loop of edge length l= 0.400 m carries a current I = 10.0A. Calculate the magnitude and direction of the magnetic field at the center of the square. 2. Relevant equations db = u_0/(4pi) * I ds x r_units vector /r^2 3. The attempt at a solution I know that that I can take out the constants, u_0/4*pi and the I and integrate ds x r_unit vector /r^2 I know also that all four sides create a magnetic field B into the page. I just don't know how to state my r. I also know that db = k* ds sin(thetha) /R^2 ( with all the constatnts factored out, k = all the constants), but I am not sure how thetha varies, i am assuming r would be l/2 if we draw our axis at the point p. but i am not sure how thetha varies.. nor ds. any help would be appreciated.