Understanding Neodymium Magnetic Field Lines
Magnetic field lines are a way to picture a magnet’s invisible field. They show the direction the field points (out of the north pole and into the south pole, outside the magnet) and its strength (lines packed closely together mean a stronger field). Neodymium magnets have densely packed lines near their poles, which is why they’re so strong up close.
Five Rules Field Lines Follow
- They run north to south outside the magnet and south to north inside it, forming closed loops.
- They never cross. At any point the field has only one direction.
- Closer lines mean a stronger field. That’s why the field is strongest at the pole faces.
- They spread out with distance, so the field weakens quickly as you move away.
- They take the easiest path. Steel gives them an easier path than air, which is how steel redirects a field.
How Shape and Steel Change the Field
Discs and Blocks
Field lines leave one flat face and wrap around to the other. Thin, wide magnets have a broad but short-reaching field.
Cylinders and Bars
Long magnets project their field farther from the ends.
Pot Magnets
A steel cup redirects the field to the open face for a much stronger hold on one side. Shop Pot Magnets.
See the Field Yourself
Lay a sheet of paper over a magnet and sprinkle iron filings on top. Tap the paper gently and the filings line up along the field lines. Keep the filings off the magnet itself; they’re hard to clean off.