What is the best way to shield magnetic fields from wiring?
First, let’s understand that the magnetic fields from a wire emanate from that wire in a pattern that could be described as concentric cylinders. The image at right represents a cross section view of a current carrying wire. Notice the concentric circles of magnetic field lines around the wire. Notice also, that the magnetic field lines are more concentrated near the wire, and less concentrated as the distance to the wire increases. Now, understanding that magnetic shielding “works” because it is a better “conductor” of magnetic field lines than air or just about any other material, let’s see what happens with 2 different shield designs. First, let’s make a shielding cylinder around the wire. In the cross section image at right, we see that the magnetic field lines that would have occurred at the radius of the shield will exist INSIDE the shield. However, magnetic field lines at all other radii will not be affected. Net effect: no shielding. But what happens if we use a flat shield? As
