Three long parallel wires are 3.8 cm from one another. (Looking along them, they are at three corners of an equilateral triangle.) The current in each wire is 8.00 A, but its direction in wire M is opposite to that in wires N and P (Fig. 20-73).
(a) Determine the magnetic force per unit length on each wire due to the other two.
(b) In Fig. 20-73, determine the magnitude and direction of the magnetic field at the midpoint of the line between wire M and wire N.

8. N -3.8 cm HP N- -3.8 - -3.8 cm.