Question about magnet


by njama
Tags: magnet
njama
njama is offline
#19
Sep10-07, 05:34 PM
P: 221
And in iron, how are the atoms bonded? Are there also polar molecules?
yyouth24
yyouth24 is offline
#20
Sep11-07, 02:14 AM
P: 16
In the iron, there are no polar molecules.
DaveC426913
DaveC426913 is offline
#21
Sep11-07, 09:36 AM
DaveC426913's Avatar
P: 15,325
Sorry, I must rescind my earlier claim that atoms do not make magnets.

Some elements have atoms with electron shells that are not paired up. Iron is one. It's 3D shell should hold 10 electrons but it only holds 6 - 2 are paired but the other four are unpaired. These unpaired four are not distributed evenly around the nucleus - and the imbalance is what creates a magnetic moment. This is what makes iron attracted to a magnet.

Further, the iron itself can become magnetized, meaning that a majority of the atoms align themselves so that their unbalanced shells line up an reinforce the overall magnetic field.


http://www.coolmagnetman.com/maghow.htm
zoobyshoe
zoobyshoe is offline
#22
Sep11-07, 02:06 PM
zoobyshoe's Avatar
P: 5,616
Quote Quote by njama View Post
Then how magnet dipole is create? There must be two poles. The electron its self is not dipole, so there must be some other charged particle like the proton. Please help. Thanks.
To understand a magnetic dipole you have to understand the magnetic field that is created around a conductor which is carrying current: it deflects a magnet (compass needle, for example) at right angles to the direction of current flow.

This site has an image illustrating this:

http://www.walter-fendt.de/ph11e/mfwire.htm

The light blue vertical rod at the center is the current carrying conductor. The darker blue rings with arrows around it show the apparent circular configuration of the magnetic lines of force that come into being around the conductor when current flows. To the right you can see a red and green compass needle; red for north, green for south. It is pointing at right angles to the direction of current flow. If we were to place it on the other side of the conductor it would continue to be deflected at right angles to the current flow, but north would be the opposite direction than it is on the present side. The north and south poles seem to go in circles around the conductor.

Now, if we make a loop of that current carrying conductor, those magnetic rings configure themselves like this:

http://www.mne.psu.edu/me415/fall04/...ic%20field.jpg

and what we see is that on top of the loop (I say "on top" since it is oriented horizontally in the illustration) all the north-pointing arrows are now curving into the center of the loop. On the bottom they are pointing out and around. This is what makes the north and south poles of a magnet. Once you understand this you can see that a magnetic monopole is simply not possible, and also that there is no need for two different charges to make a dipole.

Dave explained in a practical way why the electrons in certain atoms amount to current flowing in a loop and allow those elements to give rise to magnetic fields.
yyouth24
yyouth24 is offline
#23
Sep11-07, 04:06 PM
P: 16
Quote Quote by zoobyshoe View Post
To understand a magnetic dipole you have to understand the magnetic field that is created around a conductor which is carrying current: it deflects a magnet (compass needle, for example) at right angles to the direction of current flow.

This site has an image illustrating this:

http://www.walter-fendt.de/ph11e/mfwire.htm

The light blue vertical rod at the center is the current carrying conductor. The darker blue rings with arrows around it show the apparent circular configuration of the magnetic lines of force that come into being around the conductor when current flows. To the right you can see a red and green compass needle; red for north, green for south. It is pointing at right angles to the direction of current flow. If we were to place it on the other side of the conductor it would continue to be deflected at right angles to the current flow, but north would be the opposite direction than it is on the present side. The north and south poles seem to go in circles around the conductor.

Now, if we make a loop of that current carrying conductor, those magnetic rings configure themselves like this:

http://www.mne.psu.edu/me415/fall04/...ic%20field.jpg

and what we see is that on top of the loop (I say "on top" since it is oriented horizontally in the illustration) all the north-pointing arrows are now curving into the center of the loop. On the bottom they are pointing out and around. This is what makes the north and south poles of a magnet. Once you understand this you can see that a magnetic monopole is simply not possible, and also that there is no need for two different charges to make a dipole.

Dave explained in a practical way why the electrons in certain atoms amount to current flowing in a loop and allow those elements to give rise to magnetic fields.
And how do moving charge produces magnetic field? How do then the electrons repel (because they have same charges). By your theory if 2 electrons acting like 2 tiny dipole magnets can attract them selfs?
zoobyshoe
zoobyshoe is offline
#24
Sep11-07, 06:35 PM
zoobyshoe's Avatar
P: 5,616
Quote Quote by yyouth24 View Post
And how do moving charge produces magnetic field?
I don't know.
How do then the electrons repel (because they have same charges).
I don't know how they repell. I don't think anyone knows. It is, however, a well established property of electric fields that like charges repel.
By your theory if 2 electrons acting like 2 tiny dipole magnets can attract them selfs?
I'm not giving any personal theories here. The concept of a magnetic monopole is the "theory" here. I think it's a naive result of trying to break permanent magnets in two until you finally separate the north from the south pole. If you understand the relationship of magnetic fields to moving charges you see that such a thing isn't possible.

Two conductors carrying current in the same direction are, indeed, attracted to each other. So are two loops of wire carrying current in the same direction. Apparently, electrons traveling in the same direction are no longer mutually repulsive, but attractive (edit: at right angles to the direction of travel). Don't ask me why or how, but it is a fact.
yyouth24
yyouth24 is offline
#25
Sep16-07, 03:16 AM
P: 16
By this picture http://www.mne.psu.edu/me415/fall04/...37;20field.jpg the magnet will always be in this position.
novaa77
novaa77 is offline
#26
Sep20-07, 04:35 AM
P: 29
There seems to be some confusion here. A magnetic field is not created by an electron orbiting a protron. As per our current understanding (no one knows exactly what a magne tic field is) the movement of any charged particle whether electron or protron creats a magnetic field. Whithin an atom since the protron (nucleus) is considered to be stationary the magnetic field is created only by the rotating electron. The nobel prize is waiting for one who discovers why a charged particle creats a magnetic field.
jtbell
jtbell is offline
#27
Sep20-07, 08:13 AM
Mentor
jtbell's Avatar
P: 11,231
Quote Quote by yyouth24 View Post
And how do moving charge produces magnetic field?
It's because of Ampere's Law, which is one of Maxwell's four fundamental equations for electric and magnetic fields:

http://hyperphysics.phy-astr.gsu.edu...ric/maxeq.html

In classical electrodynamics, Maxwell's equations are postulates and have no further "explanation."
tabchouri
tabchouri is offline
#28
Sep20-07, 04:22 PM
P: 74
You have to understand that what makes a Magnet a Magnet, is not the physical parts that constites it (unlike a charge - electron or proton).
Rather, a magnet is defined by its Magnetic Field. A magnetic field is basically the movement of charges, movement more or less coherent so as to create a net Current.
I mean that there must be a net quantity of movement in certain direction to have a current.
As HallsofIvy said, an electon orbiting a nuclei generally forms a uniform cloud without an ordered movement (my apologies if i contradict any Quantum principles, correct me if so), so there is no Net Coherent Current, and thus no magnet.
(I wont speak of the spin of electrons, as it would be confusing and i dont master that enough).

Only few atoms and molecules have a net magnetic field, such as Iron (Fe) and Nickel (Ni).
That is if we apply a magnetic field on a rod of Iron, all the atoms it consists of will reorganise so to have the same direction. Thus their magnetic effect would be ordered and sum up to give the magnetic property to the rod.

-----------------------------------------------------
Correct me if i'm wrong.
http://ghazi.bousselmi.googlepages.c...3%A9sentation2


Register to reply

Related Discussions
Would running an electrical current through a magnet destroy the magnet? General Physics 4
Current-Carrying Wire/Magnet Question Introductory Physics Homework 2
what make the magnet to be magnet with magnetic field? General Physics 23
Magnet question... General Physics 9
Electro Magnet question General Physics 5