I think the steel pan bottom sitting on the hob completes the magnetic circuit, ie all the magnet lines of force are absorbed by it causing it to heat up, and very few if any, reach as far as the handle, it likes a keeper for a magnet, your line of paper clips only attracts other paper clips because its not returned to the magnet, if your line of clips are attached to say, the N pole,the free end will attract other clips until the free end is put on the S pole and then more no clips will be attracted. Hope that makes sense.