Why is there magnetism?

Question

what scientific laws of physics make it so it must exist

Answer 1

The exchange of electrons between atoms, making atoms have a charge, which creates magnetism. Depending on the direction of the spin of the electrons around the nucleus, if an unequal amount of electrons spin in two different directions, there will be magnetism.

Magnetism is also created by running an electric current through a particular substance, electromagnetism.

All materials have magnetism, but most are in a very minute amount.

Answer 2

One can only push explanation so far, but in the case of magnetism, it is possible to fall back on the movement of electric charge (of course, the next natural question would be 'why does electric charge exist?' or something to that effect, but that's beside the point). Picture a stationary charge located at the origin of the (x,y) coordinate plane. Draw a few of the electric field lines uniformly and symmetrically distibuted around it--these are very simple, going radially outward from the origin. Let's say, one line on the x-axis (y = 0), another on the y-axis (x = 0), two directly inbetween them (y = ±x), and four more directly inbetween those (y = ±x/4, y = ±3x/4). The symmetry of the lines drawn represents the fact that the force is equal in all directions. Add more as you feel necessary.

Now, suppose that the charge is moving in the positive x direction with some velocity v. According to the theory of special relativity, is measure of spatial distance will be contracted along this direction by some factor γ>1 (pick some value). That means a given point (x,y) is mapped onto the point (x/γ,y), so that, for example, any given electric field line y = mx is transformed into y = γmx. This increased density of electric force lines in the perpendicular direction of motion means that a test charge located in the perpendicular direction of the moving charge will experience more force. The magnetic field of the moving charge is then simply a way to formalize the difference between the transformed field and the stationary field without actually changing the electric field. One can view the magnetic field assimply an epiphemonon caused by insisting that the electric field is the same in both cases--in the end, that view has certain advantages, as doing the relativistic transformation on a complex collection of charges is simply not worth it, while adding up the magnetic field contributions of which is relatively easy. For mathematical details of this transformation, see, for example, J.D.Jackson, Classical Electrodynamics.

It is worth noting that the phenomenon of electromagnetic waves is also explainable in this way, although it is not mentioned in Jackson (I can't any references for it on my bookshelf; I'm recalling this explanation from deep and vague recesses of memory, but I think it was originally made by Sir J.J.Thomson, the discoverer of the electron). What is frequently found most puzzling about electromagnetic waves are that (1) they act in the transverse direction, rather than the direction of their motion, and (2) their field strength falls of inversely with distance, rather than the square of the distance. To see why, begin again with a stationary charge in the (x,y) coordinate plane, with some sample electric field lines. Give it an instantaneous impulse along the x direction to some velocity v
Of course, the above explanations handwave away a lot of mathematics, I think this picture is in some ways more intuitive and understandable for beginners, as is your case.

Answer 3

Without magnetism we wouldn't have electricity ....
Maxwell's equations (J.C. Maxwell; 1864)
Four elegant equations which describe classical electromagnetism in all its splendor. They are:
Gauss' law
The electric flux through a closed surface is proportional to the algebraic sum of electric charges contained within that closed surface; in differential form,
div E = rho,
where rho is the charge density.
Gauss' law for magnetic fields
The magnetic flux through a closed surface is zero; no magnetic charges exist. In differential form,
div B = 0.
Faraday's law
The line integral of the electric field around a closed curve is proportional to the instantaneous time rate of change of the magnetic flux through a surface bounded by that closed curve; in differential form,
curl E = -dB/dt,
where d/dt here represents partial differentation.
Ampere's law, modified form
The line integral of the magnetic field around a closed curve is proportional to the sum of two terms: first, the algebraic sum of electric currents flowing through that closed curve; and second, the instantaneous time rate of change of the electric flux through a surface bounded by that closed curve; in differential form,
curl H = J + dD/dt,
where d/dt here represents partial differentiation.
In addition to describing electromagnetism, his equations also predict that waves can propagate through the electromagnetic field, and would always propagate at the same speed -- these are electromagnetic waves; the speed can be found by computing (epsilon0 mu0)-1/2, which is c, the speed of light in vacuum.

Answer 4

The internal core of earth is formed by the internal and external parts. The internal aprt is liquid, the external one, solid. Magnetism is caused, partialy, by the friction of these two.

Answer 5

Magnetism is a relativistic effect of the motion of electrons.

Answer 6

Things like gravity and magnetism hold things together. Without them we might be a bunch of atoms disconnected and floating apart.

Answer 7

It has nothing to do with physics...magnetism exists so that Wal-Mart can sell refrigerator magnets.

Answer 8

the simple answer to this prob is that when atoms have the electrons srounding them they produce a charge. this charge like all energy has a charge to it either possitive, negitive, or nutural. so this makes to be a gigantic field that is in every part of our known universe.

Answer 9

Hmm, good question.
I'm posting because I dont know, so I can bookmark this 'answer' and come back to it.
Thanks!

Answer 10

hold s the electrons in place so they don't escape?