A previous thread asked the question as to whether gravity was an energy. The concensus was that it was in fact a force. Is Magnetism also a force and not an energy? How does phyisics define the term "Force"?
Magnetism is an <b>effect</b>. It can causes forces on objects, and it can have energies associated with it, but in itself it is neither a force nor an energy. <i>How does phyisics define the term "Force"?</i> A force is a push or a pull, which tends to cause something to accelerate.
Thanks James for takeing the time to respond to this relatively simple question. Can I ask another somewhat seemingly simplistic queation? When comparing Magnetism (cintered or rare earth - not electro magnetic) and gravity how does physics determine them as different. Apart from the fact that magnetism is predominately iron or ferrite orientated and polarised. (as a psuedo force) Can they both be treated as similar?
Magnetism is the result of a moving electrical charge. There are several causes of magnetism. All involve some net distribution of charge in a atomic nucleus and then all of them lining up to produce a net effect. You basically need charge to form magnetism. Which is why it is better to think in terms of the unified force, electromagnetism. Gravity is caused, it seems, by mass causing spacetime to 'bend' and hence store energy in it. That energy is what we fell as gravity. Though both forces superficially look the same, they obey inverse square relations etc., they have very different causes it appears. Discussions on the unification of all forces is left for another thread.
as i haven't the ability to test this I have another probably really simple question. Does an electro magnet say like a automotive use relay have two poles generated when a current is established or is it mono poled. And If it is bi poled does alternating the current polarity cause the poles to also alternate? ( I would assume this to be the case)
ALL magnets have two poles. Actually, there is some speculation that within quantum physics, monopole magnets might exist, but on the observable world level they do not. When an electromagnet is fed with AC, the poles alternate. Hans
many thanks any ideas how rare earth magnets (load stone) might have come to be? All I know is that they are dug out of the ground and that as a natural resourse there is plenty (esp in China)
Rare earth magents are not dug up anywhere. They are made of alloys that contain some metals that are rare, thus the name. The metals are, of course, mined somewhere. Hans
To backup Hans, Rare Earth is a specific term that relates to certain rare metals. Hence the term. Saying that (google, google) we have http://www.rare-earth-magnets.com/ a manufacturer of ferromagnets containing rare earth materials. It looks like Neodium is a material with extreme ferromagnet properties. That is, expose it (and an Iron and Boron mixture) to a magnetic field and it becomes strongly magnetic. As I said, some magnets are formed by the nuclei aligning to form a 'magnetic domain'. These domains then form the magnet. Last I heard there was no definite theory as to why this happens. FWIW, a lodestone is not a Neodium based magnet. It's purely iron based and has been exposed to a strong magnetic field in the past. If anyone has more uptodate information, I'm interested.
Quantum Quack, It has been my understanding that loadstone while deep under ground in a molten state rose and then cooled in the presence of the earths magnetic field. It would also seem possible that some loadstone could form during earthquakes or plate techtonics, in that an iron bar aligned with the earths magnetic field and struck with a hammer will become magnetic. That is the mechanical shock allows the crystaline structure to align while exposed to an external field.
i remember watching this movie some time ago Event Horizon which im sure most of you have seen. They had this idea of bending space and time by a huge magnetic field. i cant remember much but im very interesed to know how that theory is in a lil bit more detail. thnx gman
No, they used a man-made blackhole. They held it in place with magnetic fields. But remember....it was only a movie Please Register or Log in to view the hidden image!
ha ( an aside to the thread) movie - imagination - blackhole - imagination- theoretics - imagination - blackhole - imagination - movie - imagination seriously though, The power of the imagination has very real physical properties, how physical is debatable but if we all shared the same imagination it could very well manifest a black hole etc. Objective reality = shared imagination Subjective reality = unshared imagination I know this is off topic but.
No. Objective reality is observations that can be verified. In principle by everybody. In reality, some verifications require billion dollar budgets, so we rely on a certain amount of trust. Hans
Just thought that I'd add that string theory (or M-theory, the unification of previous string theories) predicts that there is actually only one force. As the density of matter (for lack of a better term) increases the relative strongess or weakness that defines the four forces of the standard model disapear. Physics has already proven that the electromagnetic force (attraction between positively charged protons and negatively charged electrons) and the weak force (the force that causes radiation) are actually one force, called the electro-weak force. Additionally quantum theory has unified the strong force with the electro-weak force. The goal of string theory is to unite the force of gravity with the other forces. I'd recommend the book "The elegant universe" for a much more competent discussion of this subject. A brief taste of this book was presented in a recent Nova series that you can watch online.
