# What is a simple model to find the jump height for the Thomson's Jumping Ring experiment?

I'm trying to devise a basic formula that could give a rough estimate for the jump height reached in the Thomson's Jumping Ring experiment, as detailed here.

However, it's pretty difficult as most research papers go far beyond the scope I'm looking for - essentially, I need something relatively simple that could account for the number of coils in the solenoid, the current through the solenoid, the relative permeability of the core used, possibly the temperature of the ring, possibly the ring mass, etc.

At the very least, are there any simple models to show the force between two magnets that I could start with and build on?

• Would you mind citing one of the papers that are "too complicated"? In general, if something is "not simple", then it's a bad idea to ask for an over-simplified version of it that fits ones level of knowledge. The better strategy is to upgrade ones knowledge to fit the difficulty of the problem. I can assure you about one thing: forces between magnets are NOT a simple problem. Even professionals need sophisticated numerical tools to deal with them. I can point you to a modeling tool that would allow you to calculate what you want... if you care to upgrade? – CuriousOne Apr 11 '16 at 21:20
• By all means - this paper and this paper have their own models and/or theory. I having been trying to get a greater understanding of the concepts involved that I don't understand, but I'm working at an A-level Physics standard (this is part of a project). If I go too far above this standard then I may have the opposite problem of over-compilcating my work, though like you said (1/2) – 42squiggles Apr 12 '16 at 12:23
• forces between magnets are far from simple! So I suppose what I'm trying to do is simplify the problem slightly (I don't need a particularly accurate model, after all) whilst also upgrading my knowledge? In any case, I appreciate your advice! A modelling tool would be great to look into! (2/2) – 42squiggles Apr 12 '16 at 12:32
• I can see why you would wish for the "theory" to be easier. :-) Do you have access to hardware or are you doing this theoretically? If it's the latter, you could try to simulate this first. I have had good experiences with FEMM: femm.info/wiki/HomePage. The user interface is a little quirky, but it should do what you need. The definition of the magnetic circuits are done in a text format and you could write a simple script to generate a variety of them and then produce an animation and detailed performance plots. – CuriousOne Apr 12 '16 at 19:15