Chapter 28, Problem 28.62P

Figure P28.62 shows an end view of two long, parallel wires perpendicular to the xy-plane. each carrying a current I but in opposite directions, (a) Copy the diagram, and draw vectors to show the $\stackrel{\to }{\text{B}}$ field of each wire and the net $\stackrel{\to }{\text{B}}$ field at point P. (b) Derive the expression for the magnitude of B at any point on the x-axis in terms of the x-coordinate of the point. What is the direction of $\stackrel{\to }{\text{B}}$ (c) Graph the magnitude of $\stackrel{\to }{\text{B}}$ at points on the x-axis. (d) At what value of x is the magnitude of $\stackrel{\to }{\text{B}}$ a maximum? (e) What is the magnitude of $\stackrel{\to }{\text{B}}$ when x >> a?

Figure P28.62