This one has bugged me for a while. Does magnetism actually involve 'lines of force,' along which so many beginner experiment descriptions have iron filings aligning? Or is it an actual non-discrete field effect like gravity?

Like other force fields, the magnetic field is a vector field. It has a magnitude and direction. Unlike more familiar forces, the direction is not away/toward a source since there isn't a source/sink, rather only a dipole. The iron filings allow you to see a visual representation of it -- it forms closed loops, leaving north and entering south. However "lines" have nothing to do with the force.

'S what I thought. Thanks!

Like other force fields, the magnetic field is a vector field. It has a magnitude and direction. Unlike more familiar forces, the direction is not away/toward a source since there isn't a source/sink, rather only a dipole. The iron filings allow you to see a visual representation of it -- it forms closed loops, leaving north and entering south. However "lines" have nothing to do with the force.

 

 

REPLY: How is that the iron filings form these lines and yet have nothing to do with the force itself ? Do those filings in someway interact with the magnetic force field that compels them to form lines ? It seems they must, otherwise why would those lines form ? I think it`s time for a wiki search. Regards,...Dr.Syntax from : " Get a Straight Answer" at :http://www-istp.gsfc.nasa.gov/earthmag/magnQ&A2.htm#q21 I learned that : " near a magnet,each piece of iron filings becomes a temporary magnet ". Boy the internet really is an amazing research resource. ...Dr.Syntax

Edited October 27, 200916 yr by dr.syntax
addition

Iron is ferromagnetic, so it acts as a magnet when in a magnetic field. When these small magnets are placed in a magnetic field, the magnetic force forces them to align with the field. Then you have a bunch magnetized of iron filings with their north next to the south of the next one, so that they tend to stick together. I think iron also has a greater magnetic permeability than air, adding to the effect. However, they don't form along specific "magnetic field lines" because those don't really exist. In reality what you have is magnetic field strength and a direction, but this is harder to draw hence the lines. So long as you understand that the specific lines mean nothing more than a representation of strength and direction, you're fine.

Iron is ferromagnetic, so it acts as a magnet when in a magnetic field. When these small magnets are placed in a magnetic field, the magnetic force forces them to align with the field. Then you have a bunch magnetized of iron filings with their north next to the south of the next one, so that they tend to stick together. I think iron also has a greater magnetic permeability than air, adding to the effect. However, they don't form along specific "magnetic field lines" because those don't really exist. In reality what you have is magnetic field strength and a direction, but this is harder to draw hence the lines. So long as you understand that the specific lines mean nothing more than a representation of strength and direction, you're fine.

 

REPLY: I was pretty sure you knew the answer.You seem to know very much about most everything. You`re an amazing man Mr Skeptic. ...Dr.Syntax

Geez.. Get a room you two.

REPLY, Now now, iNow, and I just gave you a positive rep point in another thread ,which I guess does not actually count because of my negative REP status. I believe I am the all time record holder with a one time, minus -88 REP points. Take Care Now,iNow, ...Dr.Syntax

REPLY: I was pretty sure you knew the answer.You seem to know very much about most everything. You`re an amazing man Mr Skeptic. ...Dr.Syntax

 

Ha ha, and there is so much that I don't know, that it would take me several lifetimes and I still wouldn't learn it all.

Ha ha, and there is so much that I don't know, that it would take me several lifetimes and I still wouldn't learn it all.

 

REPLY: I suppose the same could be said of anyone, especially with the ever expanding knowledge base. Except for those IMMORTAL AI ROBOTS due to appear most any time now. Your Friend, ...Dr.Syntax

Professor Andrew Boothroyd of Oxford University’s Department of Physics has just published a paper on magnetic monopoles (where the ‘North’ and ‘South’ poles of magnets are separated):http://www.labnews.co.uk/laboratory_article.php/4888/2/2/researchers-begin-to-crack-magnetic-mystery--

We already have a thread on this, here.