I am looking make a quick and dirty test ring using an off the shelf electromagnet. My force needs are small, less than a pound but I need to do so in a non contact manner. I know these magnets are strong but I was looking for a back of envelope formula to estimate holding force at various distances. I am thinking 1cm away from the surface of magnet. The hope is to get a 100+ lbs holding force magnets and still have a 1 or 2 lbs of hold a bit of distance away from the surface.
Thanks in advance.