Magnetic Fields

[Ant Sinclair]

If an extremely powerful electro-magnet is switched on, how quickly would it's most distant field of reach be active?, with say a magnet that could reach 13.8BLY?

 

 

[Mordred]

The electromagnetic force follows the same rules as photons in a medium/vacuum.

 

The force carrying boson is the photon. Both photons and any form of interaction/information is limitted to c in a vacuum

[Ant Sinclair]

Thank You Mordred for the reply.

The next question in relation to this is, what would the minimum field strength have to be to "just" cause an interaction with the lowest energy photon at 13.8BLY?, and if this is known could the magnetic field sources full strength at source be calculated?

[swansont]

Thank You Mordred for the reply.

The next question in relation to this is, what would the minimum field strength have to be to "just" cause an interaction with the lowest energy photon at 13.8BLY?, and if this is known could the magnetic field sources full strength at source be calculated?

 

Photons don't directly interact with magnetic fields. (I'll ignore the issues of there being a "lowest energy photon" for the moment)

[Ant Sinclair]

Thank You also SwansonT for Your reply, I see from the reply that I need to read up more on photons and so My question may have been better worded asking what would be the particle of smallest known mass influenced by magnetic fields instead of the photon?

[Mike Smith Cosmos]

Some of the great masters , established that magnetic fields do not exist on there own , but are inexorably linked to electric charge. So whatever the strange movement of electrons ,in association with an atom there is always an associated magnetic field. ( even when neutralised.

 

However often this is neutralised by opposite fields . Hence the ' two ' or electron ' pair ' idea with electrons in atoms .

With electrons in spin mode they will generate a magnetic field by dint of the moving charge.

 

You may already know this , Ant , but it's easy to forget because so many pairs are neutralised its the residual charge that makes most of chemistry work . ( might be a slight exaggeration, maybe not )

 

Mike

[Ant Sinclair]

Thanks for the input Mike, taken on-board.

[swansont]

Thank You also SwansonT for Your reply, I see from the reply that I need to read up more on photons and so My question may have been better worded asking what would be the particle of smallest known mass influenced by magnetic fields instead of the photon?

 

The smallest known mass that is affected by B is an electron. As Mike has pointed out, the particle has to be charged (and also moving) to be affected by a magnetic field, via the Lorentz force.

[Ant Sinclair]

Thanks again SwansonT for replying, would the electron-neutrino also be affected?

[Strange]

Neutrinos do not have electric charge and so would not be affected.

[Ant Sinclair]

Thanks for Your reply Strange, below is an excerpt from wikipedia. Could You suggest some "not so technical" reading on magnetic moments etc and their inter-actions or lack of with regards to magnetic fields?

 

 

The existence of a neutrino mass strongly suggests the existence of a tiny neutrino magnetic moment[16] of the order of 10−19 μB, allowing the possibility that neutrinos may interact electromagnetically as well.

Edited February 11, 2015 by Ant Sinclair

[swansont]

Neutrino magnetic moments haven't been confirmed. It's not part of the standard model, AFAIK, in which the mass is zero. If the prediction is right, it's an extremely small value.

[Ant Sinclair]

If these magnetic-moments were to be confirmed, would the neutrinos be affected by a magnetic field, and if they were affected, could this magnetic field influence their "flight" "path"?

 

Thanks again SwansonT for Your input.

[swansont]

If these magnetic-moments were to be confirmed, would the neutrinos be affected by a magnetic field, and if they were affected, could this magnetic field influence their "flight" "path"?

 

Thanks again SwansonT for Your input.

 

Yes. You could do a Stern-Gerlach type of experiment with them

http://en.wikipedia.org/wiki/Stern–Gerlach_experiment

 

They would feel a deflecting force of [math]F = -\nabla(\mu\cdot B)[/math] (just like for a neutron (pdf))

 

And, of course, the magnetic moment is (at best) really, really small.

[Ant Sinclair]

The Stern-Gerlach experiment was an interesting read SwansonT so thank You for the link.

 

If then say that neutrinos are found to have a very small magnetic-moment of say a round figure of 10 microB, could it be calculated what field strength would be required to "keep" these neutrinos out at, for want of a better description "at a geo-stationary orbit" of 13.8BLY from the magnetic sources centre?

And then could the full strength be calculated for this source and also at certain distances from source with a particular distance in mind of 800 million light years?

[swansont]

The Stern-Gerlach experiment was an interesting read SwansonT so thank You for the link.

 

If then say that neutrinos are found to have a very small magnetic-moment of say a round figure of 10 microB, could it be calculated what field strength would be required to "keep" these neutrinos out at, for want of a better description "at a geo-stationary orbit" of 13.8BLY from the magnetic sources centre?

And then could the full strength be calculated for this source and also at certain distances from source with a particular distance in mind of 800 million light years?

 

10^-19 u_B.

 

u_B is a Bohr magneton. http://en.wikipedia.org/wiki/Bohr_magneton It tells you the magnetic moment of the electron.

 

The force is due to the field gradient, which will drop off faster than the field itself. Dipoles are 1/r³, so the gradient will vary as 1/r⁴. But yes, you can take the equation and see what field gradient you need to have the force be equal to the centripetal force for a radius.

[Ant Sinclair]

After speaking to a couple of the fine gentleman that regularly partake on this forum I realise that these are not simple calculations, more learning ahead and possibly seeking a different approach to finding the answers I sought when I started this particular thread on magnetic fields.

Thanks again to Yourself, Mordred, Mike and Strange for taking the time to reply!