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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What is $a_\mu$ in particle physics? In terms of a muon; and its magnetic moment? What is, '$a_\mu$ × $10^9$ - 1165900 '?

What does $a_\mu × 10^9 - 1165900$ mean in the muon $g-2$ experiment at Fermilab?
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Why are electrons inherently magnetic? [duplicate]

I read that permanent magnetism is caused by electrons orbiting in a way which produces a net magnetic field. but how can a particle with no dimensions have a magnetic dipole? also I read that photons ...
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Review of experiment $g-2$ of the muon

This week a new development was announced to measure the pressure of the muon magnetic moment and the variation of its result on the theoretical value. The question is: what is the meaning of this ...
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Could the muon's shape be attributing to our measurements of the $g$ term for the magnetic moment?

I read that the $g$ term in the magnetic moment is being studied carefully these days in muons. I was wondering if the $L$ term was also being studied? I know that electrons have been found to be ...
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Could someone explain the muon $g-2$ experiment problem?

In the past days it was announced that the lastest results of the muon $g-2$ experiment indicates some discrepancies with the standard model. As an outsider in particle physics, I don't understand ...
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Assuming the announced $g-2$ experiment αμ discrepancy is mainly because a dark matter candidate, is this a quantum gravity induced effect?

The possible effectively extra added vacuum polarization by a dark matter candidate could account for the recently announced anomalous magnetic moment αμ measured discrepancy from the theoretical ...
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Resolving Conflicting Reports on Fermilab $g-2$ Results

Today it was announced that the Fermilab measurements of the muon's gyromagnetic ratio are in disagreement with the Standard Model with a statistical certainty reported at 4.2 sigma [1, 2], raising ...
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Induced magnetic poles in the middle of magnetic object [closed]

How are the magnetic domains aligned when one magnet is added to a middle of a long narrow object? Would it be south on both ends of the object?
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Can you magnatize the blades of an auger

Long story short im playing with mental designs of an electric motor and I'm not sure on some things regarding magmets/magnrtic materials and my designs are in flux do to these variables. I'm ...
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Can the Lorentz Force and Magnetic Moment be related?

I have learned that the Lorentz Force, $\vec F = q \vec E + q \vec v \times \vec B$, describes the electric and magnetic forces on a charge, such as a proton or an electron. I understand that, 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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Can neutrons be manipulated with magnetic fields? Can neutron particle accelerators be built?

Neutrons have no electric charge and do not respond to electric fields as in a conventional particle accelerator. However, they are magnetic and do have a small magnetic dipole moment. So it should ...
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Field of an infinitely wide magnetic dipole

Students commonly wonder about the near-analogies between electricity & magnetism. One such: The field of an electric dipole in the limit of an infinitely wide plane tends to 0 outside the plane (...
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Determining critical exponent in spontaneous magnetization of 2D Ising model

I have been solving a problem related to Onsager's relation in Ising model. The initial relation is: $<s>^8=1-sinh(\frac{2J}{k_BT})^{-4}$ I got that critical temperature is $\frac{2J}{k_BT}=sinh^...
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Deuteron magnetic moment for $l=2$

Considering the Deuteron in its $l=2$ state, I dont understand why its magnetic dipole moment is composed of $3$ terms: $$ \mu_d = \mu_n + \mu_p + \mu_{orb}$$ where the first two are the intrinsic ...
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Magnetic potential for the electron

Citing my professor's book: The magnetic moment associated with the orbital motion, somewhat corresponding to a current, can be derived from the Hamiltonian for an electron in a static magnetic field ...
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Why cant we treat electron as a dipole in nucleus' magnetic field in this way in hyperfine structure?

In hyperfine structure modifications, the magnetic field due to magnetic moment of nucleus couples with the orbital angular momentum of the electron. The interaction(perturbation) term of the ...
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What is the Lorentz's force equation for a moving segment of current-carrying wire?

According to Griffths's Electrodynamics textbook, the magnetic force on a segment of current-carrying wire is $$\mathbf{F} = \int I (d\mathbf{l} \times \mathbf{B}) $$, when the path of the flow is ...
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Can particle spin actually show quantum effects like the disruption of measurement?

I was going through a quantum objects course on brilliant.org, a few things have been bothering me and though I searched A LOT I can't seem to find any answers. For one, the course implies that a ...
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Why does spin, and not total angular momentum, couple to the magnetic field in a Stern-Gerlach experiment?

I understand that the dynamical principle behind a Stern-Gerlach experiment is the coupling of a magnetic dipole moment to a (non-homogeneous) magnetic field. I also understand that when an electric ...
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Is the anomalous magnetic dipole moment due to interactions with the QED Vacuum?

I am pretty sure that it is, from what (little, so far) I understand, but... Most of what I have read about the anomalous magnetic dipole moment and it's contribution to the electron's $g$-factor do ...
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Why aren't common magnets made of magnetite, $\rm Fe_3O_4$? Instead of ferrite, $\rm Fe_2O_3$?

Why are common, simple, cheap magnets like refrigerator magnets made (usually) of hematite ($\rm Fe_2O_3$) in some form, like 'ferrite', instead of the more magnetic and magnetizable magnetite ($\rm ...
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Which of these magnets should have the strongest strength at 10cm?

Basically, I need to generate the strongest possible field at 10 cm from a circular magnet, in its central axis. I hesitate about what buying. For example, the following magnet has a large diameter of ...
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Magnetic dipole in gradient magnetic field

I know that a magnetic dipole in a uniform magnetic field will precess. What happens qualitatively (or quantitatively) to a magnetic dipole in a gradient magnetic field? According to Wikipedia, "...
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At what distance does magnetic attraction between two properly aligned electrons cancel electric repulsion?

Electrons have both magnetic dipole moments and charge. Two electrons separated by a distance would repel electrically but it stands to reason they would rotate their spins so their magnetic poles ...
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Invariance of magnetic moment in slowly-changing magnetic fields (plasma physics)

I am trying to understand how the magnetic moment is invariant in slowly changing magnetic fields. There is a proof in the textbook I am using, but I'm stuck on how $-e\int\frac{\partial B}{\partial t}...
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Why does calculation of magnetic moment of electron depend on mass?

All of the calculations I have seen for the magnetic moment of electrons include the electron's mass in the calculation. Why would this be relevant? The calculation for magnetism of macroscopic ...
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When does a stationary state have zero magnetic moment?

If the Hamiltonian is invariant under parity, nondegenerate energy eigenstates cannot carry permanent dipole moment because $\langle n|{\vec r}|n\rangle=0$. Is there a similar property of the ...
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General expression for magnetic Field due to a finite solenoid

The expression for magnetic field inside a solenoid is well know to be nearly constant and also for an infinite solenoid the magnetic field outside is zero. But generally a finite solenoid is used as ...
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Is there any fundamental relationship between the torque on a classical magnetic moment due to a field, and the Lorentz force on a moving charge?

I was studying recently and noticed that the torque on a magnetic moment due to a field is defined as $\tau = \mu \times B$. Classically, as far as I'm aware, the magnetic moment is given by $\gamma L$...
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How is the magnetic dipole moment operator defined?

In quantum mechanics, the electric dipole moment operator is defined as $$\hat{\vec D}=q\hat{\vec r}$$ where $q$ is the electric charge of the distribution. This is directly obtained by promoting ...
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Magnetic field lines of a toroid magnet

I am not sure what are the magnetic field lines of a torroid magnet like this one: In particular, at the center of the magnet, is the field null or is it maximal?
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Why does a compass feel a force when placed in a magnetic field?

The magnet has its own magnetic field and the same goes for the compass. So whenever I place a compass near a magnet, the magnetic field lines of both the compass and the magnet must interact to ...
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Range of the RKKY interactions

I read that RKKY interaction has a longer range than just the nearest-neighbor distances. Approximately, do you know by about how long this range could be? Better, what is the longer range that has ...
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What does it mean that a neutron has a 'negative' magnetic moment?

Most questions about this ask why, or how, a neutron has a magnetic moment at all, or why it is negative.... But I am curious as to what it means, physically or experimentally, for a magnetic moment ...
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Are the units for the magnetic moment correct for this paper?

Can the units of $$\frac{e\,c}{2\pi\,f},$$ where $c$ is the speed of light, $e$ is the elementary charge and $f$ is the frequency, be correct for the magnetic moment? I see that the units of magnetic ...
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How is magnetic dipole “created”?

I know that the electric dipole can be created when the electron cloud is displaced realative to the nucleus. I am trying to draw parallel to this and to better understand this topic, so please help ...
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Why do neutrons have magnetic moments with spin?

Neutrons are neutrally charged, but apparently they have magnetic moments with spin. What is the intuition behind this?
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References on motion according to minimization of Magnetic Energy

When you tell people involved in science "everything in nature obeys to a principle of minimization of some energy" usually they are not (too much) surprised. However, I need to provide some ...
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What would be the induced EMF of a hollow sphere moving in linear direction transverse to a constant magnetic field?

This is how I visualized the question- Now, as we know, induced EMF is the change in magnetic flux- $$ EMF = − \frac{N\Delta\Phi}{\Delta t} $$ And as for the magnetic flux- $$ \Phi_B = \iint_A \...
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Why do we only include core electrons in Larmor diamagnetism?

In the Larmor diamagnetism derivation of a susceptibility $\chi = -\mu_0 \frac{\rho e^2}{6m} <r^2>$, we are told to use the density of core electrons as $\mu$ and not all of the electrons in the ...
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Contradiction with rectangular slab in uniform $B$ field

I am considering a case of a rectangular slab of linear magnetic and insulating material (with non-zero magnetic susceptibility $\chi$) in a uniform magnetic field and I am experiencing a ...
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Magnetic dipole moment of volume current derivation

The multipole expansion of the magnetic potential yields the dipole term : $$\mathbf A_{dipole}(\mathbf{r}) =\frac{\mu_0}{4\pi r^{2}}\int (\hat {\mathbf r} \cdot {\mathbf r}') \mathbf J {dV}'$$ How do ...
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Multipole expansion to approximate magnetic field of two currents with given distance and the field of a dipol with given momentum in 2D

I tried to approach this problem numerically, and someone pointed out that this was a classical multipole expansion problem. I dont know anything about multipole expansion, So i ask for help here. My ...
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Ampere's law when there is current density as well as surface current

We all know Ampere's law stating that: \begin{equation} \dfrac{1}{\mu_0}\left(\boldsymbol{\nabla\times}\mathbf{B}\right)\boldsymbol{=}\mathbf{J} \tag{01}\label{01} \end{equation} But what will happen ...
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Magnetic dipole moment because of spinning electron

We always consider only the spin of electron. But protons are spinning charges as well. So what about the magnetic dipole moment caused by them?
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Does the new measurement of the fine structure constant rule out string theory?

I am no expert in either string theory or experimental physics, but I was reading this article by Nature, where it is quoted: This result confirms, for example, that the electron has no substructure ...
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A non-magnetic screwdriver suddenly becomes magnetic and attracts screw when working near brushed DC motor containing permanent magnet

When I was disassembling my R/C quadcopter, I had to take out the screw holding the plastics. As i completely unscrew one of the screw near the brushed DC motor, the screw was adhered to the ...
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How to approximate electromagnet-magnet interaction

I need a simple model of a small electromagnet interacting with a small magnet. The core of the problem is "If the magnet is located in this position, what about the attraction of the ...
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Magnetic moment produced by a charge in translatory motion (with no orbital motion)

A moving charge produces a magnetic field, while its magnetic moment is given by $$\mu = -g\frac{q}{2m}\textbf{L}$$ where, $g$ = gyromagnetic ratio, $q$ = charge, $m$ = mass, L = orbital angular ...

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