If a permanent magnet is allowed to hang from an overhead steel plate, the magnetic field resisting the pull of gravity holds the magnet to the beam. Energy seems to be created?
If an electromagnet is energized with adequate current it creates a force that can attach a magnet to an overhead plate, it uses energy constantly.
Does this mean that magnets defy the conservation of energy law by creating energy?
2007-06-27 20:30:33 · 7 answers · asked by oneirondreamer 3 in Science & Mathematics ➔ Physics
Thank you for the best so far answers zwink, and know it all. I am not sure that I agree entirely thought. Gravity seems to exert a force consistantly, wether a body is in motion or not? That force is most easily measured as mass? If I bolted the magnet in place it would be said that the bolt is doing work, and if the bolt were to small it would eventualy break from the force.
No one has been willing to comment on wher the force in the electromagnet goes? If no force is required once the magnet is in place (force= accell X mass?) then why would it fall once it was denergized?
Thanks for the answers so far
2007-06-28 15:31:21 · update #1
Yes magnet creates energy, it's very small (compare to what atoms might have) and if you wait long enough it'll loose energy and it's magnetism. It's the energy already available as a potential in atoms/electrons. Think that when you mix Hydrogen and Oxygen, they merge and create heat before turning into water. Where the heat comes from?
2007-06-27 20:50:13 · answer #1 · answered by rexxyellocat 5 · 0⤊ 3⤋
Your logic is not correct. The force of attraction is more than the force of gravity and so the magnet is held to the beam. There is no work involved (the work of taking the magnet to the beam is done by you) in the magnet staying there. Force x distance = work or Kinetic energy = 1/2 m.v^2 and in this case, no velocity is present.
In the case of an electromagnet the domains in the material don't stay aligned when the current is swiched off and hence the magnetic field disappears.
In the case of the permanent magnets some extra energy was spent in aligning the domains thus creating the magnet.
2007-06-28 04:16:52 · answer #2 · answered by Swamy 7 · 1⤊ 0⤋
balancing a magnet on a magnetic field, is in situation exactly the same as laying down a cartrage of cigarettes on a tabel.
youre balancing forces. when balanced ofcourse newtons law applies again: wont move until acted upon by an external force. (hence requiring energy.)
2007-06-28 04:15:45 · answer #3 · answered by mrzwink 7 · 1⤊ 0⤋
In any case you consider the law of conservation of energy will never be violated even if it may seem to.
2007-06-28 10:15:43 · answer #4 · answered by Shobiz 3 · 0⤊ 0⤋
No.
Energy is only released when a force MOVES.
All the forces you mention stay firmly put.
2007-06-28 03:41:51 · answer #5 · answered by Anonymous · 1⤊ 2⤋
permanent magnet doesn't exist......it is a ideal case.........
2007-06-28 09:16:08 · answer #6 · answered by no_fe@r 4 · 0⤊ 0⤋
No, no work is done.
2007-06-30 13:39:10 · answer #7 · answered by johnandeileen2000 7 · 0⤊ 0⤋