Register to reply

What make the magnet to be magnet with magnetic field?

by scientist91
Tags: field, magnet, magnetic
Share this thread:
scientist91
#1
May14-07, 11:50 AM
P: 133
Answer please. Thank you very much. I am talking about permanent magnet.
Phys.Org News Partner Physics news on Phys.org
Physicists discuss quantum pigeonhole principle
First in-situ images of void collapse in explosives
The first supercomputer simulations of 'spin?orbit' forces between neutrons and protons in an atomic nucleus
Hootenanny
#2
May14-07, 02:57 PM
Emeritus
Sci Advisor
PF Gold
Hootenanny's Avatar
P: 9,781
Scientist, I again reiterate what I said in your previous thread; forums are not an ideal medium from which to learn basic physical principles, you would be much better served with an elementary undergraduate physics book. That said I offer a brief summary of magnetism.

Magnetism is a direct affect of atomic magnetic dipoles, which itself results from two quantum mechanical properties of atomic electrons. Firstly, the electron has an orbital angular momentum which is determined by orbital angular momentum quantum number which falls out of the Schrödinger Equation. This "orbital angular momentum" should not be confused with classical angular momentum in so much as electrons in an atom do not obey classical orbits. This orbital angular momentum results in an orbital magnetic dipole moment which behaves as a classical magnetic dipole moment (think tiny bar magnet).

The second, more dominant factor, is the electron "spin". Again, this spin should not be confused with classical spin (the electrons in an atom don't actually spin on their axis), it is merely a quantum mechanical description of the electron state. Again, this spin quantum number results in a spin magnetic dipole moment.

Now, to occupy the lowest energy states (magnetic dipole moments have an associated potential energy in the presence of a magnetic field) the electrons tend to 'pair up' with other electrons so that their magnetic moments cancel each other out in a full shell/sub shell, it is the partially filled shells/sub shells which result in a net magnetic dipole moment. The atomic dipole moment is simply the sum of all the individual orbital and spin magnetic dipole moments. Therefore, elements / substances with certain configurations / partially filled [sub]shells will be magnetic.

Magnetic Dipole Moment @ Hyperphysics (better than wiki)
Magnetic Dipole Moment @ Wikipedia
scientist91
#3
May15-07, 02:08 AM
P: 133
Quote Quote by Hootenanny View Post
Scientist, I again reiterate what I said in your previous thread; forums are not an ideal medium from which to learn basic physical principles, you would be much better served with an elementary undergraduate physics book. That said I offer a brief summary of magnetism.

Magnetism is a direct affect of atomic magnetic dipoles, which itself results from two quantum mechanical properties of atomic electrons. Firstly, the electron has an orbital angular momentum which is determined by orbital angular momentum quantum number which falls out of the Schrödinger Equation. This "orbital angular momentum" should not be confused with classical angular momentum in so much as electrons in an atom do not obey classical orbits. This orbital angular momentum results in an orbital magnetic dipole moment which behaves as a classical magnetic dipole moment (think tiny bar magnet).

The second, more dominant factor, is the electron "spin". Again, this spin should not be confused with classical spin (the electrons in an atom don't actually spin on their axis), it is merely a quantum mechanical description of the electron state. Again, this spin quantum number results in a spin magnetic dipole moment.

Now, to occupy the lowest energy states (magnetic dipole moments have an associated potential energy in the presence of a magnetic field) the electrons tend to 'pair up' with other electrons so that their magnetic moments cancel each other out in a full shell/sub shell, it is the partially filled shells/sub shells which result in a net magnetic dipole moment. The atomic dipole moment is simply the sum of all the individual orbital and spin magnetic dipole moments. Therefore, elements / substances with certain configurations / partially filled [sub]shells will be magnetic.

Magnetic Dipole Moment @ Hyperphysics (better than wiki)
Magnetic Dipole Moment @ Wikipedia
Ok, man thank you. I know the basics of the physics, but it is hard for me to understand on the English language because it is not my first language. I am from Macedonia so it is hard for me to translate and understand what you're saying, and also I don't know the conceptions on English language. And do u have any picture of that orbital angular momentum? Where do the electrons are moving, different orbital or something? Why some magnetised materials lose their magnetic field? What make the electrons to have that orbital angular momentum?

ZapperZ
#4
May15-07, 07:08 AM
Emeritus
Sci Advisor
PF Gold
ZapperZ's Avatar
P: 29,239
What make the magnet to be magnet with magnetic field?

If you have a problem in trying to ask a question, and you also have a problem in understanding the answers you were given, don't you think this whole exercise is becoming rather futile?

Here's what I strongly suggest that you do:

1. Read the references given, especially at Hyperphysics.

2. Now, using THOSE references, try to understand the relevant sections that could answer your questions.

3. After you have made an effort to understand those, and if you still could not figure those out, ONLY THEN should you ask here. But don't ask some basic, generic question that requires a whole lesson in physics to understand. That is impossible to do on a forum like this. Ask the specific item that you read that you did not understand. Give the exact reference and the exact location what and where you did not understand.

If not, I don't think anyone has the patience to want to teach you whole textbooks worth of physics. I certainly don't.

Zz.
scientist91
#5
May15-07, 10:53 AM
P: 133
Quote Quote by ZapperZ View Post
If you have a problem in trying to ask a question, and you also have a problem in understanding the answers you were given, don't you think this whole exercise is becoming rather futile?

Here's what I strongly suggest that you do:

1. Read the references given, especially at Hyperphysics.

2. Now, using THOSE references, try to understand the relevant sections that could answer your questions.

3. After you have made an effort to understand those, and if you still could not figure those out, ONLY THEN should you ask here. But don't ask some basic, generic question that requires a whole lesson in physics to understand. That is impossible to do on a forum like this. Ask the specific item that you read that you did not understand. Give the exact reference and the exact location what and where you did not understand.

If not, I don't think anyone has the patience to want to teach you whole textbooks worth of physics. I certainly don't.

Zz.
I can't understand so help me.
Hootenanny
#6
May15-07, 11:09 AM
Emeritus
Sci Advisor
PF Gold
Hootenanny's Avatar
P: 9,781
Quote Quote by scientist91 View Post
I can't understand so help me.
To reiterate what Zz is saying and what I have said previously; Forums are not suitable mediums for learning new concepts or material, they are very good if you have specific questions regarding specific parts of physics. You have my sympathy, but this is compounded by the language barrier between a predominantly English speaking forum and your own native language.

What you are essentially asking me/us to do is present virtually whole lectures on parts of physics where you have little or no grounding, this is a virtually impossible task on a forum and even if it were, I am not willing to invest the and effort that it would take. Now, I don't mind offering help to those who have fairly specific questions, and I don't mind writing extended posts, I usually have PF open while I'm working and just check for new posts every now and again; but what your asking is for us to basically write a physics textbook for you. I'll repeat again, you would be best served purchasing an elementary physics textbook or at least reading the references I gave you because from your questions it doesn't seem to me that you have read the links.

Again, I sympathise with your language barrier but you would be best served with a textbook (or at least reading the references).
scientist91
#7
May17-07, 12:54 AM
P: 133
and is the magnetic field energy?
Hootenanny
#8
May17-07, 02:16 AM
Emeritus
Sci Advisor
PF Gold
Hootenanny's Avatar
P: 9,781
Quote Quote by scientist91 View Post
and is the magnetic field energy?
The magnetic field is not actually energy itself; the magnetic field is a pseudo-vector field, that is, it is just a way of associating a vector with a given point in space. However, magnetic [and electric] fields can store energy such as in an inductor[or capacitor in the case of an electric field]. The energy density (U/V) in a magnetic field (B) can be calculated thus;

[tex]\frac{U}{V} = \frac{B^2}{2\mu}[/tex]

You should realise that the magnetic field is simply a relativistic consequence of the electric field.

P.S. There's no need to tack your question onto the bottom of another [unrelated] thread; you should post new questions as new topics. Thanks
scientist91
#9
May17-07, 04:03 AM
P: 133
Quote Quote by Hootenanny View Post
The magnetic field is not actually energy itself; the magnetic field is a pseudo-vector field, that is, it is just a way of associating a vector with a given point in space. However, magnetic [and electric] fields can store energy such as in an inductor[or capacitor in the case of an electric field]. The density (U/V) in a magnetic field (B) can be calculated thus;

[tex]\frac{U}{V} = \frac{B^2}{2\mu}[/tex]

You should realise that the magnetic field is simply a relativistic consequence of the electric field.

P.S. There's no need to tack your question onto the bottom of another [unrelated] thread; you should post new questions as new topics. Thanks
Ok, but I don't want to post every topic for every question, so I am searching for similar topics. So how it stores energy?
Hootenanny
#10
May17-07, 04:11 AM
Emeritus
Sci Advisor
PF Gold
Hootenanny's Avatar
P: 9,781
Magnetic Potential energy @ Hyperphysics
Energy Stored in an Inductor / Magnetic Field @ Hyperphysics
scientist91
#11
May17-07, 06:22 AM
P: 133
Answer please. Thank you.
Hootenanny
#12
May17-07, 07:26 AM
Emeritus
Sci Advisor
PF Gold
Hootenanny's Avatar
P: 9,781
Quote Quote by scientist91 View Post
Why the magnet attract iron and why the magnet is not attracting wood?
Answer please. Thank you.
Why do you think that a magnet attracts iron but not wood?
scientist91
#13
May17-07, 12:11 PM
P: 133
Quote Quote by Hootenanny View Post
Why do you think that a magnet attracts iron but not wood?
try you will see. btw-when the magnetic field is making the electrons obey their upper orbital and make energy circle and then when they release their energy, go down.
Hootenanny
#14
May17-07, 02:41 PM
Emeritus
Sci Advisor
PF Gold
Hootenanny's Avatar
P: 9,781
Quote Quote by scientist91 View Post
try you will see.
No, you try and see. I expect you to show a little effort to understanding the material.
Quote Quote by scientist91 View Post
btw-when the magnetic field is making the electrons obey their upper orbital and make energy circle and then when they release their energy, go down.
I honestly have no idea what your talking about
scientist91
#15
May18-07, 01:14 AM
P: 133
Quote Quote by Hootenanny View Post
Magnetism is a direct affect of atomic magnetic dipoles, which itself results from two quantum mechanical properties of atomic electrons. Firstly, the electron has an orbital angular momentum which is determined by orbital angular momentum quantum number which falls out of the Schrödinger Equation. This "orbital angular momentum" should not be confused with classical angular momentum in so much as electrons in an atom do not obey classical orbits. This orbital angular momentum results in an orbital magnetic dipole moment which behaves as a classical magnetic dipole moment (think tiny bar magnet).
And then which orbitals they obey?

Quote Quote by Hootenanny View Post
The second, more dominant factor, is the electron "spin". Again, this spin should not be confused with classical spin (the electrons in an atom don't actually spin on their axis), it is merely a quantum mechanical description of the electron state. Again, this spin quantum number results in a spin magnetic dipole moment.
And then on which axis they spin?
jackiefrost
#16
May18-07, 07:27 AM
P: 137
Hootenanny - could you explain a little more about why you used the term "pseudo-vector field" to describe the magnetic field? Because of its relativistic nature? Thanks.
Hootenanny
#17
May18-07, 10:43 AM
Emeritus
Sci Advisor
PF Gold
Hootenanny's Avatar
P: 9,781
Quote Quote by scientist91 View Post
And then which orbitals they obey?
I was simply trying to say that the electrons do not 'orbit' around the nucleus as you would probably imagine. Rather there is some non-zero probability that they exist at some distance from the nucleus; the most probable position [for a given energy level] corresponds to a circular ring around the nucleus somewhat like a classical orbit. However, for any given energy level (n) [and low orbital quantum number (l)], there is some non-zero probability that the electron can be found very close to the nucleus. Therefore, it is best not to say that electrons orbit around the nucleus, rather there is some probability to find an electron somewhere in the electron 'cloud' around the nucleus. I'm afraid that this is elementary QM and will probably seem very 'weird' and counterintuitive if you are encountering it for the first time.
Quote Quote by Physics Forums FAQ; Why don't electron's crash into the nucleus in atoms? By Marlon and Edited by ZapperZ
It turns out that the picture of electrons moving in circular orbits around the nucleus isn’t correct either(*). The solution here is the implementation of Quantum Mechanics via the Schrödinger Equation and the concept of wavefunction. By applying such formalism, the “electron” occupies a volume of space simultaneously, so that it is “smeared” in a particular geometry around the nucleus. While there are no more “orbits”, we do use the term “orbitals” to indicate the shape of such geometry. However, this term should not be confused to mean an orbiting electron similar to our planets in the solar system. By describing the system in terms of the QM wavefunction, it creates stable states for the nucleus+electrons system that matches very well with experimental observation of standard atomic spectra.
Quote Quote by scientist91 View Post
And then on which axis they spin?
They don't spin at all.
scientist91
#18
May18-07, 12:59 PM
P: 133
Look man, when there is magnetising the electrons from the lower orbitals gain energy and go into the upper orbitals, so they are spining around the nuclei (circular spinning), and when they release their energy, then they make circle of energy, that is the magnetic field, and then (after they released their energy) go into the lower energy level so the magnetic field is around the electrons


Register to reply

Related Discussions
How can a permanent magnet produce magnetic field? General Engineering 20
Induction of a coil and force exerted on magnet in a magnetic field Classical Physics 1
Modeling the magnetic field of multiple magnet bars General Physics 4
What is maximum magnetic field strength of SC magnet General Physics 2
Calculating Magnetic field of permanent magnet Classical Physics 1