Hello 1. The problem statement, all variables and given/known data A disc magnet of radius R and height H attracts a mild steel plate. Coercive force Hc, Remanence Br and Bhmax are known. Main problem is to find an approximative formula that gives the pull force of the magnet at a given distance x. :shy: I have found a formula that gives the force (eq.2), but the results are 4 times smaller then the experimental results. [PLAIN]http://img293.imageshack.us/img293/2019/clipboard01aj.jpg [Broken] 2. Relevant equations Eq.1 [PLAIN]http://img707.imageshack.us/img707/1124/img0028144742812.png [Broken] Eq.2 [PLAIN]http://img833.imageshack.us/img833/730/img0017144742796.png [Broken] 3. The attempt at a solution Experiment: Neodymium magnet N48 @0mm - F=42N @0.1mm - F=33N Next step it will be to try the FEA analysis with Quickfield, but I need tiny analytical relations Thank you!