Thread: physics question

02022006, 08:28 PM #1
physics question
i have been asked to describe in words what the physical meaning is of maxwell's equations. i know that the point of the first equation is that electric fields diverge, and that the point of the second equation is that magnetic fields always curl onto themselves (there are no magnetic monopoles) but i am having dificulty describing the main point of the third and fourth equations ( ampere's law, and faradays law). my question is not what the equations are ( i already have the integral form and the derivation of the differential form) i was wondering if anyone knows the physical meaning of ampere's law and faraday's law.

02022006, 08:41 PM #2
here are the two equations im talking about. the first is amperes law, and the second is faradays law

Well see if the proton and the electron force each other in an elliptical orbit and ...................
nevermind i am physic alliterate

02022006, 08:50 PM #4
Man  I took this stuff like 20 years ago so if it helps great  if not...sorry.
Amperes Law  Had something to do with a visual of a straight wire...the tangential magnetic field around a closed loop to the current that passes through the loop  like the field around the wire.
(I had to look up tangential BTW)
Faradays had to do with changing the magnetic field of a coil wire and it's effects on voltage.

02022006, 09:17 PM #5
faradays law seems strange to me because it says that the line integral of the electric field dotted into a differential length along a closed curve is equal to the negative derivative of the magnetic flux with respect to time, but maxwells second equation states that the magnetic flux always equals zero... god damn it, i really need to understand this
Last edited by Tren Bull; 02022006 at 09:45 PM.

02022006, 09:27 PM #6
Not sure what level you're working at, but:
http://en.wikipedia.org/wiki/Maxwell_equations
Feynman's second Lecture book (buy 'em all if you're a physics major/minor)
"Geometrical Vectors" from UChicago Press (Great book geometrically describing vector relations and visualising div, curl, grad and other operations)
What school do you go to?
:cow:

02022006, 09:30 PM #7
im finishing up my last semester at a community college. next semester il be going to chico state

02022006, 09:32 PM #8
Ampere's law basically says that the magnetic field which exists around a given current I, is proportional to that current. If you would like more details surrounding the equation then I'll write more.
Faraday's law is really cool. It says that a change in a magnetic field in a looped wire will generate emf in the wire. There are some neat flashlights out that utilize this very principle. You shake the flashlight which passes a magnet through a coil of wires and stores the charge so you never need batteries.

02022006, 09:36 PM #9
By the way Faraday's law is also the source of all magnetic fields. It is true in reverse as well (moving electrical point charges generate magnetic fields). Atoms which unpaired electrons in outer energy orbitals generate small magnetic fields. Put a bunch of them together (like in the center of the earth) and you generate a large magnetic field.

02022006, 09:37 PM #10Originally Posted by symatech

02022006, 09:42 PM #11Originally Posted by symatech

02022006, 09:58 PM #12Originally Posted by Tren Bull
Quantum Mechanics is my favorite field of study, I like reading and working QM almost as much as I like whiskey...and I'm a man who likes his whiskey!
ps. the wave particle duality is one of the most beautiful things in nature. yeah i said it...im a nerd

02022006, 10:11 PM #13
the way i look at it, its ok to be amazed by these things... especially if you're totally roided out.

02022006, 10:13 PM #14
hit up johan, i know he took a physics class on magnetic fields and is genuinly interested in physics.

02022006, 10:13 PM #15
btw, i remember telling some girl about how we defract when we walk through a doorway, or any openeing for that matter... she wasn't impressed

02032006, 06:44 AM #16Originally Posted by symatech
NERD I cant wait to get into QM more indeepth. The only class I have taken was a introduction to QM, nuclear and atomic physics.
I want to work with relativistic QM

02032006, 06:48 AM #17Originally Posted by symatech
Thats a good description.
I have been thinking about this alot myself. My EM class was not good. We had a great professor but because of budget cut downs ect the class was REALY stressed through(especialy considering the EM field class was BEFORE we took linear algebra so we had to half ass our way through vector calculus). So I got a grasp on how to calculate EM fields but not much understanding on what the hell Im acctualy calculating.
The moment I get some time over Im going to have to go through the entire course again on my own.

02032006, 06:54 AM #18
When I get home from my girl Il se what feynman writes in his lecture books and write it out here

02032006, 07:04 AM #19
when talking about QM. The one thing I dont like with QM and the schrödinger equation is that it has no real physical meaning, not one that I have seen so far .
Its just a tool to calculate probabilities of a stochastic phenomenon.
It doesnt give intimate understanding. Just a way to do calculations. I guess this is why Einstein wasnt pleased with quantum mechanics allthough it gave so accurate results that no one can deny the theory is right.
I guess the question is simply. What real wave is the schrödinger equation describing. The slim answere that its the probability that is waving isnt realy pleasing to me.

02032006, 07:09 AM #20Originally Posted by symatech
http://physicsweb.org/articles/world/17/11/7

02032006, 09:37 AM #21Originally Posted by symatechOriginally Posted by symatech
Oh no I took all of this a few semesters ago. Bringing back some horrible memories, glad its all over.. Fheeeeeeeeeeeeeew

02032006, 03:13 PM #22Originally Posted by johan

02032006, 03:20 PM #23
you know what i find is really amazing? the theory that light travels as a wave, but colapses into a particle when it hits a surface. so its not just that light has wave like properties and particle like properties, it literally is both. i really haven't studied this in detail at all though, ive only heard about it. anyone know more about this?

02032006, 03:32 PM #24
opposites attract

02032006, 04:25 PM #25Anabolic Member
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Powers of magnetism?
(Reminds me of a little electric motor, or a power generator.)
ah yes... paramagnetic and diamagnetic... you know you can elevate a non ferrous material such as a piece of plastic or a frog with diamagnetic fields? That's something you'll like reading into
anyhoo..
Ampere's Law says that the energy around a closed loop is proportionate to the energy flowing through the loop.
As for the faraday's law says any magnetic change around a coil wire will creat voltage, and it doesn't matter how the change occurs, it will stll produce energy.
Is this right. i don really remember all this lol... im such a goon :P

02032006, 05:47 PM #26Originally Posted by Tren Bull

02032006, 05:49 PM #27
but even when you calculate probability flux/current I think its a very odd process. I cant get a physical feeling for what a probability flux is. I can just work calculations on it. But I guess its because its unnatural to think of a particle not having a fixed location at every given point in time.

02032006, 08:12 PM #28Originally Posted by johan

I know how to make a vacano with bake soda and vinegar !

02032006, 09:56 PM #30Originally Posted by DSM4Life

02032006, 09:59 PM #31
Quantum Mechanics is really cool imo. And I'm going to make a thread about it at another day when I have more time and motivation. It will be brother to my string theory thread years back I'll go into detail about what I like and don't like about it, but why as a whole I enjoy it.

Very interesting theory  it makes no sense at all.
I do not like it, and I am sorry I ever had anything to do with it.
God does not throw dice with the cosmos
Who are you to tell God what to do
If that turns out to be true, I'll quit physics
Nobody understands quantum mechanics

02032006, 10:02 PM #32
i have heard many times by my teachers that nobody understands quantum mechanics... so far from what i have seen im believeing it.

02042006, 05:03 AM #33
Syma how come your such a big fan of string theory??? I havent read all that much about it but I think its a very hmm unattractive theory of everything. Dont know why it just a feeling I get. Especialys since its not falsifiable in the close future and like my theoretical physics professor said. To even work with string theory you need to be a mathematical genious. Just gifted/talented doesnt cut it when it comes to string theory
When something gets so horribly complex I dont think its right ;(
He told a story of one very bright student he had that did his doctor thesis on string theory and it got published and was well recived but after another 2 years the poor dude just gave up. He said he couldnt possibly work with the theory anymore because its so terribly complex.
I REALY hope this theory will turn out to be right
http://en.wikipedia.org/wiki/HeimTheory
If it doesnt get falsified within the coming 3 years I think Im going to do my doctorate thesis on heim theory. The little I have read is just amazing. Especialy the particle mass predictions.
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