Aran613 Posted February 18, 2012 Share Posted February 18, 2012 We all know that an object in motion stays in motion, unless acted on by an outside force. And most of us know that spinning a copper wire around a magnet (or the opposite) will "generate" electricity. But in space, deep in space, there is no force to act upon an object. What if you were to conduct that in space? If you began to spin the copper wire, it wouldn't stop moving, would it? If it didn't stop, wouldn't that be "creating" energy, disproving the law of conservation of energy? Just curious, Aran613 Quote Link to comment Share on other sites More sharing options...
VincentASM Posted February 18, 2012 Share Posted February 18, 2012 (edited) I haven't done physics in ages, but I'm pretty sure the copper wire would stop eventually because there *is* a force acting on it. For instance, wouldn't the magnet generate a field that opposes the copper wire's movement? I should check my textbook... EDIT I think it might have been Lenz's Law Edited February 18, 2012 by VincentASM Quote Link to comment Share on other sites More sharing options...
Grace Posted February 18, 2012 Share Posted February 18, 2012 (edited) The only reason there wouldn't be a force is if space was a perfect vacuum. But, space isn't (it gets really close at points), so eventually the wire will stop. So, you require a certain amount of energy to make that wire spin. Energy is imparted to the wire, and it converts it to not just electrical energy, but probably heat energy or similar during its movement. Or something like that, it's been a good 3 months of not thinking about physics. Take this with a grain of salt. Edited February 18, 2012 by Manix Quote Link to comment Share on other sites More sharing options...
Lord Raven Posted February 18, 2012 Share Posted February 18, 2012 (edited) Call me stupid but what do you mean spinning a copper wire around a magnet? You're saying the wire is a loop and the magnet is going through it or what? I need sort of a visual representation, because there wouldn't be infinite energy if I'm thinking of the problem the way you are. VincentASM is correct though; in a conducting loop, the loop will create/induce a magnetic field that opposes the change in magnetic flux. When a magnet enters the loop, the flux is increasing; as a result, this induced will magnetic field will attempt to repel the magnet so that the flux can go back to its original configuration again. This gets rid of the electrical energy if this repulsion occurs. There is no infinite energy because in order to maintain this, you must actively keep a force on the magnet to oppose the induced magnetic field. Once again, I hope I'm understanding your question correctly. Edited February 18, 2012 by Mercenary Raven Quote Link to comment Share on other sites More sharing options...
Aran613 Posted February 18, 2012 Author Share Posted February 18, 2012 Call me stupid but what do you mean spinning a copper wire around a magnet? You're saying the wire is a loop and the magnet is going through it or what? I need sort of a visual representation, because there wouldn't be infinite energy if I'm thinking of the problem the way you are. VincentASM is correct though; in a conducting loop, the loop will create a magnetic field that opposes the change in flux. When a magnet enters the loop, the flux is increasing so the magnetic field will attempt to repel the magnet so that the flux can go back to its original configuration again; this gets rid of the electrical energy. There is no infinite energy because in order to maintain this, you must actively keep a force on the magnet to oppose the induced external magnetic field. Once again, I hope I'm understanding your question correctly. Yes, that's what I meant. And thanks everyone, I see what you all mean. Quote Link to comment Share on other sites More sharing options...
Lord Raven Posted February 18, 2012 Share Posted February 18, 2012 (edited) np i reworded my response to make it clearer btw.. Edited February 18, 2012 by Mercenary Raven Quote Link to comment Share on other sites More sharing options...
Blitz Posted February 19, 2012 Share Posted February 19, 2012 I thought the forces would be the electronic waves and magnetic waves and no actual electron transfer. Quote Link to comment Share on other sites More sharing options...
Lord Raven Posted February 19, 2012 Share Posted February 19, 2012 (edited) A change in flux causes the electrons inside a conducting loop to move (since a conductor, by definition, is a material where electrons are free to move; technically a bunch of things are conductors but some are more conductive than others) thereby causing a current and therefore causing a magnetic field.. Edited February 19, 2012 by Mercenary Raven Quote Link to comment Share on other sites More sharing options...
lancerusso Posted February 20, 2012 Share Posted February 20, 2012 I haven't done physics in ages, but I'm pretty sure the copper wire would stop eventually because there *is* a force acting on it. For instance, wouldn't the magnet generate a field that opposes the copper wire's movement? I should check my textbook... EDIT I think it might have been Lenz's Law *nods* Yeah, this basically. Conservation of energy tells us that this should be true regardless. Lenz's Law says that the direction of the current induced in the wire is such that a magnetic field propogates that stops the motion- and It's effectively an expression of the conservation of energy in electromagnetism. Quote Link to comment Share on other sites More sharing options...
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