In the figure below four long straight wires are perpendicul

In the figure below, four long straight wires are perpendicular to the page, and their cross sections form a square of edge length a = 15.0 cm. Each wire carries 5.50 A, and the currents are out of the page in wires 1 and 4 and into the page in wires 2 and 3. What is the magnitude and direction of the net magnetic force per meter of wire length on wire 4?
= _____ N/m
= _____ ° (counterclockwise from the positive x axis)

Solution

Using Ampere s law B=u_oi/2r, here current I= 5.50A. R= 15cm=0.15m. Permeability of space =4×10^_7Tm/A. B=4×10^_7×5.50/2×0.15. B=11×10^_5/15=0.00000733N/m. =45° counter clock wise Direction in positive x Direction.