일반물리학 2 — Maxwell's Equations; Magnetism of Matter: Problem 24

Two wires, parallel to a z axis and a distance 4r apart, carry equal currents i in opposite directions, as shown in Fig. 32-25. A circular cylinder of radius r and length L has its axis on the z axis, midway between the wires. (a) Use Gauss’ law for magnetism to derive an expression for the net outward magnetic flux through the half of the cylindrical surface above the x axis. (Hint: Find the flux through the portion of the xz plane that lies within the cylinder.) (b) Evaluate the flux for current i = 2.40 A and length L = 3.40 cm.