I am a teacher and am in the process of developing labs dealing with magnets. I have seen calculators on the internet that can calculate the pull force in pounds for a magnet when provided the shape of magnet, thickness, diameter and Br value in gauss. I have failed to find the equation used for such calculations, can you point me in a direction where I may find such equations? I would like to develop a lab where my students can use a Hooks Law apparatus and measure the force needed to separate a magnet from a plate of metal. And then place layers of plastic between the magnet and metal and measure the force again. Any help would be great.