/sci/ - Science & Math

>>9760532
>Why do magnetic fields not follow the inverse square law

They do.

>>9760532
Because the field lines don't spread out radially like light or gravity or electric charge.
They curve around and re-enter the magnet at the other pole.

The fall-off varies both with distance and with your angle from the dipole-moment (the line connecting the poles).
>https://en.wikipedia.org/wiki/Magnetic_field

>>9760536
Not really. In what what way?

>>9760532
Biot savart law. Maxwell's equations.

>>9760554
By distance.

>>9760560
Are you sure? Distance from what?

>>9760532
Because our current understanding of reality is a approximation via stuff that "kinda" works and the more shit piles up the less sense everything makes. In 100 years some guy is going to get a brilliant idea that will render all science of the last 200 years from then on moot and hopelessly outdated, making future people look back in bewilderment how we even managed to build calculators when everything we did was wrong, retroactively rendering billions of scientists' life achievements completely pointless because they wasted their lives playing a very complex game of sudoku. But at least they were happy doing it.

>>9760532
They're dipoles. Which means the 1/r^2 term gets cancelled out and you're left with 1/r^3.

I wish I could understand but I've only done up to high school physics (starting an undergrad in Physics in October)

Here's another question, why do we say that field lines go from 'North to South' when it can clearly be seen in a solenoid that they go from South to North as well?

>>9760577
>, why do we say that field lines go from 'North to South
By definition. Also field lines arent physical, think if vector fields instead. We could have called the tail of the B vector the tail and the head the head. Then we'd say they point from tail to head. The vectors on the outside arent the same as the vectors on the inside.

>>9760614
We call it north and south because this whole magnetism poles shit started with compasses, and the convention just stuck

>>9760577
Field lines don't actually exist, but they're such a useful mental construct I doubt we'll ever abandon them.
They simply show the direction of the vector field at every point and the "spacing" between the lines shows the field intensity.
"Field lines never end" is equivalent to "there are no discontinuities in the field" or "there are no magnetic sources or sinks".

If a magnetic monopole IS ever found (they're permitted by quantum theory) you can be sure that the field lines which seem to "disappear" into a point will emerge again from a pole of opposite polarity somewhere else.
The poles would still be connected (and the field lines continuous) even though the connection would be undetectable.
>https://en.wikipedia.org/wiki/Aharonov%E2%80%93Bohm_effect
All that would happen is that an additional term would be added to Maxwell's equations (making them completely symmetrical) in the rare cases when a monopole lay within the volume under study.

Field lines "exist" as much as vector fields. The problem with field lines is that to mathematically construct them, you already must know what the field is. They are pretty useless.

>>9761681
Physically, field lines can be observed with iron fillings. They are extremely thin vortices and carry angular momentum.

>>9761681
>(making them completely symmetrical)
more symmetry idiocy. This is the same obsession that kept us from figuring out the true orbits of the planets for a couple of centuries.

they do follow the inverse square law though. It's just the direction of the force that is weird, but it still scales as the inverse square

>and then I went and spoiled it all by saying something stupid like....I like...you..

>>9760558
this

>>9760564
The distance isn't a straight line. The field curves.

>>9760532
They are dipoles, so they follow the inverse cube law. If monopoles exist they follow the inverse square law.