Can Magnets Do Work? - Exploring a Thought Experiment

In summary, the conversation discusses a proposed perpetual motion machine involving magnets and magnetically shielding material. The idea is that the top magnet will pull the bottom magnet up when the shielding material is removed, and the bottom magnet will fall back down when the material is put back in place. However, it is pointed out that this scenario will not work because the magnetic field itself has energy and the shielded configuration is a lower energy state. This means that work will have to be done to move the shield, making the machine not truly perpetual. The conversation ends with the individual asking for clarification on how the shielding material works.
  • #1
MadMike1986
23
0
Before I get flamed for proposing a perpetual motion machine, I would like to point out that I understand there is something fundamentally flawed in my logic. That is why I am posting this, I want someone to point out to me what I am missing to explain why this won't work.

Suppose you have two magnets positioned so that their opposite poles are facing toward each other. There is a magnetically shielding material in between the two magnets so that they do not move into contact with one another. Now suppose one magnet is held in place by a stop and the other magnet is free to move and located underneath the first with the magnetically shielding material somewhere in between the two but free to be slid in and out of the device. When the magnetically shielding material is removed, the top magnet pulls with enough force to move the bottom magnet up and into contact with the stop. Now the shielding material is slid back into the system and the bottom magnet falls back down. This can be done repeatedly. We now have devised an engine that can do work.

In my little thought experiment this seems completely valid to me, however i know something must be wrong. I would love to test this out physically but i don't have any magnetically shielding material. Can anyone point out to me why this will not work?

Thank you.
 
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  • #2
And how much energy is used to slide the shield in and out of position?
 
  • #3
i don't know, are you suggesting that perhaps sliding the shielding material would take the same amount of energy as is being used by the bottom magnet moving upward. I have no idea how magnetically shielding material works, but i can only assume that it involves some sort of interaction with the magnetic field. I suppose that could explain it.
 
  • #4
I think that may be it. the "Magnetic shielding" material would itself act like a magnet. Magnetic dipoles within the material flip to cancel the magnetic field of the lower magnet. It would take work to pull this material out of the way.
 
  • #5
Hi MadMike, the bottom line is that magnets can do work but your scenario won't work for the reason alluded to by f95toli.

The magnetic field itself has energy, if you have a magnetic shielding material then that material reduces the magnetic field which means that a shielded configuration is a lower energy state than an unshielded configuration. The magnet will therefore do work on the shield as you put it in and it will take an equal amount of work to pull the shield out.
 

FAQ: Can Magnets Do Work? - Exploring a Thought Experiment

Can magnets really do work?

Yes, magnets can do work. Work is defined as the application of force over a distance, and magnets are able to exert a force on other objects without making physical contact with them. This force, known as magnetic force, can be used to do work such as moving or lifting objects.

How do magnets do work?

Magnets work by creating a magnetic field around them. This field is what allows magnets to exert a force on other magnetic objects, such as attracting or repelling them. When this force is strong enough, it can do work by moving or lifting the objects.

Can magnets do work without touching an object?

Yes, magnets can do work without touching an object. This is because the magnetic force they exert can act over a distance, without the need for physical contact. This is why magnets can attract or repel other objects without ever touching them.

Can magnets do work in a vacuum?

Yes, magnets can still do work in a vacuum. The absence of air or other materials does not affect the magnetic force that a magnet can exert on other objects. This is because the magnetic field created by a magnet is not affected by the presence or absence of air or other materials.

What is a thought experiment about magnets doing work?

A thought experiment about magnets doing work is a hypothetical scenario that explores the concept of magnetic force and its ability to do work. It may involve imagining how magnets could be used to move or lift objects without making physical contact, or how their force could be harnessed to create energy. These experiments help us understand the principles behind magnetism and its potential applications in the real world.

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