Walker, Halliday & Resnick — Magnetic Fields Due to Currents: Problem 15

15 Figure 29-33 shows wire 1 in cross section; the wire is long and straight, carries a current of 2.50 mA out of the page, and is at distance d1 = 4.00 cm from a surface. Wire 2, which is parallel to wire 1 and also long, is at horizontal distance d2 = 5.00 cm from wire 1 and carries a current of 6.80 mA into the page. What is the x component of the magnetic force per unit length on wire 2 due to wire 1?