# Questions tagged [magnetic-moment]

The magnetic moment of a magnet is a quantity that determines the force that the magnet can exert on electric currents and the torque that a magnetic field will exert on it. A loop of electric current, a bar magnet, an electron, a molecule, and a planet all have magnetic moments.

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### Does a magnet effect moving weight [closed]

If i take a tube and put 2 opposite magnets in it (so that they bounce off eachother), and then i put a rock ontop of one magnet. Would the amount of pressure needed to push te magnet with the rock up ...
1 vote
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### Magnetic dipole moment due to folded loop [closed]

A steady current i flows in a small square loop of wire of side L in a horizontal plane. The loop is now folded about its middle such that half of it lies in a vertical plane. Let $μ_1$ and $μ_2$ ...
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### Is it right assume the greater the precession of a type of particle in the same magnetic field the slower the particle spin?

Is it right that the greater the Larmor frequency of a particle measured for same magnetic field applied the slower a particle spin is? I read these articles http://hyperphysics.phy-astr.gsu.edu/hbase/...
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### Magnetic Dipole Moment of a single electron of a hydrogen atom CM vs QM

An electron in orbit is a good approximation of a magnetic dipole so n the introduction of chapter 8 in the book: "Quantum Physics of Atoms, Molecules, Solids, Nuclei and Particles", a classical ...
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### What's the magnetic moment induced by an external magnetic field on a ferromagnetic material?

How do you model the magnetic moment that's induced by an external magnetic field? So basically if you have an external B field, and we put a ferromagnetic rod in that field, what would be the rod's ...
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### How to design a coil for neodymium magnet speaker [closed]

For reasons I won't elaborate in depths here here I need to design a speaker-like oscilating element, that is ring shaped so it fits onto a suction cup so it can be easily attached to any flat surface ...
1 vote
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### Method for calculating nuclear magnetic moments

I am having difficulties computing the magnetic moment for an even-odd (proton-neutron) nucleus. The formula is: $$\mu_J=g_J\times j\times \mu_N$$ I checked this helpful post: When calculating ...
1 vote
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### Paleo-magnetism for the solar system over millions of years from the widmanstatten pattern?

I understand that the widmanstatten pattern (long fingerlike crystalline structure of iron nickel meteorites) is due to a slow cooling and solidification of asteroids over tens of millions of years. ...
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### Permanent magnets - why spontaneous symmetry breaking?

I am not a physicist. I'm curious about the cause of permanent magnetism in ferromagnetic materials. So far, I have formed the impression that a macroscopic net magnetic dipole moment is formed from ...
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### Why armature is being rotated in DC generator?

I am wondering about why armatures are being rotated instead of being static? The magnetic flux will still cut the armature windings and because of this induced current will be generated. So, why it ...
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### Larmor Frequency for Spin Transition

http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/larmor.html Consider the process of Larmor precession of the magnetic moment associated with the spin angular momentum of an electron inside a ...
1 vote
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### Do Protons and electrons actually have magnetic poles?

From what I’ve read protons and electrons only are attracted to each other because they have opposite electric charges. What I don’t understand, though is that I’ve also read that both protons and ...
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### Why would giving a 90 degree Radiofrequency pulse to a ZERO longitudinal magnetisation cause zero transverse magnetisation in MRI?

Let's imagine in my scenario the (a) in the picture above has no net longitudinal magnetization (therefore 0 longitudinal). Why would giving an 90° RF pulse in my scenario not cause the Protons to ...
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### How does QM explain the proton's magnetic moment?

I read that QM is baffled by the proton's angular momentum, I don't know if the issues are related, but do you know if and how it explains the odd value of the magnetic moment of the proton and of the ...
1 vote
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### Hamiltonian of an electron in a magnetic field

Suppose I have an electron in a magnetic field given by: $$\vec{B}=B\hat{z}$$ The potential energy of this system is given by: $$U=-\vec{\mu} \cdot \vec{B}=\frac{g\mu_B}{\hbar}\vec{S} \cdot \vec{B}$$ ...
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### Repulsive Force between two cuboidal magnets

I have 2 cuboidal permanent magnets(same grade) which are kept a small distance apart. They are kept such that they will repel each other. How do I calculate the force of repulsion between them? I ...
1 vote
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### How do I show mathematically that net intrinsic magnetic moment of a substance is $0$?

The following argument is made, keeping in mind the classical theory of diamagnetism. I'm not including the correct quantum mechanical theory in this question. Consider a material in the absence of ...
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### Goodenough-Kanamori rules

Could anyone elaborate more on Goodenough-Kanamori rules or guide me to the right textbook for this? For example, the Goodenough-Kanamori rule predicts a ferromagnetic interaction between d5 with t2g3 ...
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### Ferromagntism and Canting Moment from Antiferromagnetism

There is a thin-film sample that shows a ferromagnetic-like hysteresis loop, but the bulk material is known to be an antiferromagnetic material with small canting, and the canting moment will make the ...
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### Are magnetic surface current real?

In the book "Introduction to Electrodynamics, 4th edition" by Griffiths, the author says, I quote from page 278 : (...) We call it a "bound" current to remind ourselves that every charge is ...
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### Back-of-the-envelope calculation of electron anomalous magnetic moment

I wonder if there is an intuitive way to obtain the $\frac{\alpha}{2\pi}$ correction to electron's $\frac12 (g-2)$ just like how Bethe estimated the Lamb shift? Here is an attempt by Drell & ...
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### Quick question regarding Larmor precession and bar magnets

So I was just reading a bit about magnetic dipole moments, Larmor precession, angular momentum etc., but there was one little thing that was bothering me. As far as I know, any angular momentum will ...
1 vote
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### How to reduce magnetic field between two magnetic shield sheets (silicon steel sheets)?

I put 2 parallel silicon steel sheets between magnetic field as below: As silicon steel has much bigger permeability than air,magnetic line will go through 2 silicon steel sheets. What I can do to ...
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### Why does magnetic dipole's north pole pointing in the direction of magnetic field increases overall magnetic field?

I'm studying magnetic moment- current loop, electron/proton/charge revolving, magnetic dipole etc. This is about paramagnetism of materials. According to me magnetic dipole's south pole is attracted ...
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### How to calculate pole strength for this magnet?

I know magnetic mono poles don't exists and a magnetic poles always have equal strength. But what about a magnet which looks like this? This is picture of magnet whose thickness is constantly ...
1 vote
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### Maximum $B$-field at the surface of a permanent magnet

I have the dipole formula for a permanent spherical magnet in coordinate-free form. $\vec{B}=\frac{\mu_{0}}{4\pi}\frac{3(\vec{m}\cdot\hat{r})\hat{r}-\vec{m}}{r^{3}}$ I am trying to find the maximum $B$...
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### Electron to electron interaction

I am interested to know if it would be possible to calculate the magnetic attraction between two electrons at zero space between their magnetic poles against electrostatic repulsion between them in ...
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### Force and potential energy between two magnetic dipoles

I have a question about two magnetic dipoles in the form of coaxial current carrying loops both of radius $r_0$ a distance $h_0 \gg r_0$ apart. Using $h_0 \gg r_0$ we can assume the B-field from one ...
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### Why Is an Inhomogenous Magnetic Field Used in the Stern Gerlach Experiment?

The apparatus used in the Stern Gerlach experiment is somewhat like the one shown below with magnetic pole pieces of different shapes producing an inhomogeneous magnetic field. But what would have ...
### Why is the Anomalous magnetic dipole moment defined as half the extra contribution to the $g$-factor?
Was there a reason Julian Schwinger or Richard Feynman officially defined the anomalous magnetic moment as half of the extra $g$-factor? $$a = \frac{g-2}{2}$$ (equation is from the Wikipedia article ...