http://http://session.masteringphysics.com/problemAsset/1074673/3/knight_Figure_32_14.jpg [Broken] that is the diagram that accompanies the question. The 3 parts of the question ask what is the magnetic field strength at points 1, 2 and 3. I know that B=B_1+B_2+.... for each point. In order to find the strength of the field at a point you must take into consideration all forces. I also know that u_0/4pi*(I s cross r/r^2) gives the strength of the magnetic field at a point, as does (u_0*I)/(2*pi*d) I have attempted the problem several times, and keep using the second equation from above for the points on the outsides of the 2 wires (points 1 and 3). However, I keep getting the answer incorrect. I haven't started point number 2, but I think once I figure out the principle behind points 1 and 3 it will come easier.