our long, straight wires are parallel to each other and their cross-section forms a square. Each side of the square measures 0.0112 m.

If each wire carries a currrent of 8.33 A in the direction shown, find the magnitude of the total magnetic field at P, the center of the square.


For this question I tried using B=(mu*I)/(2*pi*d) and multiplying the answer by 4 cuz there are 4 sides but my answer is not correct.

 

You have to assume a positive direction of current flow. Say the dot is the positive direction and the cross is the negative direction. Thus find B each wire causes at point P and then add them together. According to, the assumptions, the right-bottom wire will give a negative B and the other wires positive B.