일반물리학 2 — Magnetic Fields Due to Currents: Problem 8

8 In Fig. 29-26, four long straight wires are perpendicular to the page, and their cross sections form a square of edge length \(a = 7.00\text{ cm}\). Each wire carries \(15.0\text{ A}\), and all the currents are out of the page. In unit-vector notation, what is the net magnetic force per meter of wire length on wire 1?