Solved: Figure 29-64a shows, in cross section, three

Chapter , Problem 38

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Figure 29-64a shows, in cross section, three current-carrying wires that are long, straight, and parallel to one another. Wires 1 and 2 are fixed in place on an x axis, with separation d. Wire 1 has a current of 0.750 A, but the direction of the current is not given. Wire 3, with a current of 0.250 A out of the page, can be moved along the x axis to the right of wire 2. As wire 3 is moved, the magnitude of the net magnetic force Fz on wire 2 due to the currents in wires 1 and 3 changes. The x component of that force is Fl , and the value per unit length of wire 2 is FlJ L2. Figure 29-64b gives FlJ L2 versus the position x of wire 3. The plot has an asymptote Fl/L2 = -0.627 fLN/m as x -> 00. The horizontal scale is set by Xs = 12.0 cm. What are the (a) size and (b) direction (into or out of the page) of the current in wire 2?