i have little questions which make me banging my head against the wall over the last few days. now, before too many walls collapsed:yuck: : 1. can anyone direct me to an easy reference which explain how to calculate demagnetization factor N for simple geometries (such as long cylinder, thin films, etc). remember, a simple one! not ellipsoids!! 2. i believe demagnetization arises because of the boundary effect. is this correct? to be exact, how? i thought this is because at the boundary (if we talk about a cylindrical magnet with magnetization along its axis) the dipole moment there does not have a pair. is this correct? can anyone explain in cleaner way? 3. and why the sum of demagnetization factor in all 3 axes is always unity? or is it? for those who attempt good response, i would thank very much. especially gokul43201 who responded my few questions in the past. thanks for the help.