Can a superconducting magnet maintain its magnetic field indefinitely?

[WarPhalange]

This isn't a homework problem, but I figured I'd post it here since it's a pretty basic question, in my view at least.

So my professor and Senor Griffiths have been telling me this for the past year. Cool. Now I'm working on a project that uses a superconducting magnet.

So I started to think, and here's my question:

If I have a superconducting magnet, i.e. a solenoid that has I guess you call it persistent current running through it at 0 Ohms, it will (or should) have it's magnetic field for almost infinity.

Now if I introduce a wrench into the system, the B-field will attract it and bring it closer. As this happens, will the B-field lose strength because it is transferring energy to both the wrench and magnet itself as kinetic energy?

If I do this very slowly so that when they touch, very minimal heat is released (so I guess the B-field is low), what would happen if I pulled them apart again? I'm guessing the magnet would not inscrease in strength once more. Am I thinking correctly?

 

[Jhero]

Thank you for bringing up this interesting question. Your understanding of superconducting magnets and their behavior is correct. Superconducting magnets are able to maintain a persistent current and magnetic field for a very long time due to their zero resistance, which allows for the current to flow without any energy loss.

When you introduce a wrench into the system, the magnetic field will indeed attract it and bring it closer. This will cause a transfer of energy from the magnetic field to the wrench, resulting in a decrease in the strength of the magnetic field. However, this decrease will be very small and may not even be measurable in most cases.

If you were to pull the wrench and magnet apart again, the magnetic field would not increase in strength. This is because the energy that was transferred to the wrench is now stored in the form of kinetic energy, and the magnetic field will not be able to regain that energy. Therefore, the strength of the magnetic field will remain the same as before.

I hope this helps clarify your question. Superconducting magnets are fascinating and have many unique properties that make them useful in various applications. Best of luck with your project!