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Hi - On this forum, dgreenheck on May 20, 2013 touched on this area. I will post my question in this manner:
Say one has a solenoid with a given number of turns; if the core is air, we know that if we run 10 amps through the circuit, the energy to charge a magnetic field to "B" Tesla is recovered when the magnetic field collapses. Now if that core is iron instead of air, we know the magnetic field is greater than the original "B" value (assuming no saturation), due to the permeability of iron. My question is: when that field collapses, does one recover the same amount of energy as before (with the air core), or more energy that is contained in the larger "B" field? It would seem against all rules of conservation of energy that one would get more energy back, but where does that extra field energy go? This is a puzzle to me? You can't get something for m\nothing!
Say one has a solenoid with a given number of turns; if the core is air, we know that if we run 10 amps through the circuit, the energy to charge a magnetic field to "B" Tesla is recovered when the magnetic field collapses. Now if that core is iron instead of air, we know the magnetic field is greater than the original "B" value (assuming no saturation), due to the permeability of iron. My question is: when that field collapses, does one recover the same amount of energy as before (with the air core), or more energy that is contained in the larger "B" field? It would seem against all rules of conservation of energy that one would get more energy back, but where does that extra field energy go? This is a puzzle to me? You can't get something for m\nothing!