How does a magnet’s strength drop off over distance?
The strength of a magnetic field drops off roughly exponentially over distance.
Here is an example of how the field (measured in Gauss) drops off with distance for a Samarium Cobalt Grade 18 disc magnet which is 1” in diameter and 1/2 “ long.
Distance, x | Field at Distance, x |
0.063 | 2,690 |
0.125 | 2,320 |
0.188 | 1,970 |
0.250 | 1,660 |
0.313 | 1,390 |
0.375 | 1,160 |
0.438 | 970 |
0.500 | 810 |
0.563 | 680 |
0.625 | 580 |
0.688 | 490 |
0.750 | 420 |
0.813 | 360 |
0.875 | 310 |
0.938 | 270 |
1.000 | 240 |