Question

The four wires that lie at the corners of a square of side a= 4.20 cm are carrying equal currents i= 1.70 A into (+) or out of (-) the page, as shown in the picture.

Answer 1

Calculate the y component of the magnetic field at the center of the square.

Answer 2

and thus do the same for all four wires
\[B=\frac{ \mu _{0}i }{ 2\pi r }.\] and their components is cos45=sin 45. for all four wires.