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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I Bring 1 kg of Iron to a Flux Density of 1 T. How Much Energy Does That Take?
I'm an EE, not a physicist, so please forgive if this question is dumb.
I learned a bit of magnetics when I took motors 20 years ago, but I don't remember much.
I'm reaching out to the physics ...
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Magnetic moment [closed]
I'm not calculating a magnetic moment of even nuclear (odd protons+odd neutrons). results of taking according to a nucleon shell-model of Shmidt do not match experimentl resauls for calculating ...
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How does the Lagrangian work with a magnetic field?
I was told the following Lagrangian is for a charged particle with spin moving in a constant magnetic field:
$$
L = \frac{\left ( \vec p \right ) ^2}{2m} + \vec \mu \cdot \vec B$$
Let's just say $B$ ...
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Absorption Cross Section for Two-Level Spin System in an AC Magnetic Field - Photon Picture
For a two-level spin with a energy difference of $E = h f$, where the two levels have zero dipole electric coupling and can only be driven by a magnetic field, how do I calculate the absorption cross ...
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How to interpret Magnetic Susceptibility as the ratio of two vectors $M$ and $H$, as division of two vectors is not defined in mathematics?
Magnetic Susceptibility, denoted as χ is defined as a scalar, represents the ratio between the Magnetization vector ($\vec {M}$) and the Magnetic field strength vector ($\vec{H}$).
However, in ...
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Intuition for magnetic dipole moment
The definition of the electric dipole moment of a system of charges makes sense intuitively -
$$\boldsymbol {\bf p} = \int_{V} \boldsymbol {\bf r} \rho (\boldsymbol {\bf r})dV$$
describes the overall ...
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Explanation of why Kinetic Energy Increases when Particle Reaches the End of the Magnetic Bottle?
I don't understand how to explain why kinetic energy increases using Faraday's Law as a charged particle reaches the end of a magnetic bottle.
I know that along the field line in the bottle, the ...
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Do magnetic fields cause rotational inertia proportional to their magnetic moment?
If I have a stick that has a spinning disc on the end of it, and I try to rotate the stick, I will feel more inertia the faster the disc is spinning because I have to transform its rotational energy ...
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What is the physics behind Oasis Mini?
A ball placed in the sand is moving around and drawing magnificent art. In the video below it draws a dolphin. It is very precise.
How does it work?
https://www.youtube.com/shorts/2b291H4uHAY
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Can the electron $g$-factor be understood as electrons having roughly twice as much momentum as the Bohr Magneton?
I'm trying to make sure I understand the $g$-factor of the electron, so if my question is flawed please don't just point out my flaws, but help me correct my understanding
If I understand correctly ...
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Why is magnetic field due to magnetization $M$ (net dipole moment per unit volume) of a material given by $B=\mu_0M$?
(Magnetization $M$ of a sample is defined as the net magnetic dipole moment per unit volume.)
If, for example, the interior of a solenoid is filled with a material of non zero magnetization, the field ...
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Magnetic Force on a Ferromagnetic Material
Consider a ball or bullet made of a Ferromagnetic material (such as pure iron) in a Magnetic Field, Does the Magnetic Force applied to the ball calculate via this formula?
$$F = \nabla(m.B)$$
Can ...
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Why do compasses always align with the magnetic field, when the spin of individual particles only align half of the time?
If I have an electron orbiting a nucleus and I apply a magnetic field there will be two effects:
Larmor precession given by the cross product of the magnetic moment and the field of the experiment
$$...
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Why is water diamagnetic, but water protons align with external field in NMR?
I recently re-learned today that water is diamagnetic. I don't believe I totally understand why, but I will accept it as true.
However, I remember that in NMR of water, the protons of water form ...
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How is the local magnetic moment determined experimentally?
The Anderson model is contrived to explain the existence/nonexistence of local magnetic moments in metallic solutions.
It is said that for a solution of A atoms in B metal, sometimes there are local ...
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Spin magnetic dipole moment of electron not an invariant with acceleration?
Since the energy of the electron at rest can be calculated by:
$$
E_e=\frac{h c}{ \lambda_e}
$$
where $\lambda_e$ is the Compton wavelength value of the electron at rest, $h$ the Planck constant and $...
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How can we define Magnetic Potential Energy if it is non-conservative?
I recently learnt that for a circular wire carrying electric current or for a magnetic dipole, if it is kept in a uniform magnetic field, we can define its magnetic potential energy. This would mean ...
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The Earth's Magnetic Field and the Apparent Contradiction with Geographic Poles
"Regarding the Earth's magnetic field generation, it is said to be a result of the rotation of molten materials in the Earth's outer core, which generates electric currents. We know that the ...
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Magnetic coexistence curves, and the magnetic Clapeyron equation
Suppose I am interested in a simple magnetic system. In particular, in the phase diagram in the $B_e-T$ plane for a simple ferromagnet; assume no magnetocrystalline anisotropy and assume the external ...
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Metals and Magnets
A metal is attracted by a magnet when placed in it's vicinity. I was wondering if it is the metal that moves towards the magnet, or is it that both the metal and magnet move towards each other? Could ...
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Where does force act in two parallel current carrying conductors?
F=ILB.so consider length as 5 m and I as 2 ampere and B as 5 T.so the force is 50 N.does this 50 N act at one point or equally applied on full length like pressure.So what does force/length in this ...
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Do we experimentally know how a magnet reacts in a curling / non-zero-curl magnetic field?
There are two possible formulas for the magnetic force on a magnetic dipole moment due to the inhomogeneity of the magnetic field:
$$ \vec{F}_{A} = \nabla (\vec{m}\cdot\vec{B}) \qquad\text{ and }\...
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How does magnetic moment vector arise from spin 1/2 spinors?
In NMR a hydrogen proton magnetic moment is a vector due to spin, but spin 1/2 like protons are spinors, not vectors, so how does spin 1/2 spinor give rise to an actual magnetic moment?
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Does this basic example of two bar magnets preserve angular momentum conservation?
Let's say I hold two bar magnets side by side both vertically aligned ($z$-axis). I don't want to worry about their shapes, so let's approximate them as dipoles. I will use the dipole formula rather ...
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Prove $\frac{\mu}{L}=\frac{\frac{Q}{2}}{M}$ [closed]
I was studying magnetism. I encountered a relation but with no proof. It was a statement. It says
If for a body, charge and mass distribution is same then $$\frac{\mu}{L}=\frac{\frac{Q}{2}}{M}$$
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Can we derive the magnetic dipole moment of a current loop from the Lorentz force on it?
I would like to derive $\boldsymbol{\mu}$ for a current loop where $\boldsymbol{\mu}$ is defined by the relationship between torque on the current loop resulting from it being in a magnetic field,
$$\...
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Does string theory predict any small variation in the magnetic moments of charged elementary particles from the predictions of QED?
Does string theory predict a slightly different magnetic moment for charged elementary particles than QED does? I suspect there should be some variation if only because rather than particles being ...
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Accuracy of finding electron's magnetic moment
In the little book QED, Feynman says:
"experiments have Dirac’s number at 1.00115965221 (with an uncertainty of about 4 in the last digit); the theory puts it at 1.00115965246 (with an ...
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Contracdicting qualitative statements regarding magnetic polarization
Consider a cube of metalic material (either it is paramagnetic or diamagnetic can be both discussed). An external magnetic field $\textbf{B}$ is applied along the +x axis.
We expect $\textbf{B}$ to be ...
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Why is the magnetic field due to a dipole at equatorial position opposite to the magnetic moment?
I understand that the direction of the magnetic field lines at the equatorial plane is opposite to the direction of the magnetic moment by definition. Is there a reason of physical significance as to ...
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Where the Magnetic moment and angular momentum relation is valid?
There is a relation between angular momentum and magnetic moment as
$$M/L = q/2m $$
where $M$ is magnetic moment and $L$ is angular momentum. So this relation is valid for which cases?What are some ...
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Spin magnetic moment and external magnetic field, stable state
I am having a hard time understanding when the electronic state, represents a more stable state, when we consider an electron with spin exposed to an external magnetic field.
The spin magnetic moment ...
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If you stacked Jupiter and Saturn pole-to-pole (magnetically) on top of each other, would the magnetic force come close to the gravitational one?
The titular question should say it all. Let's assume they're essentially touching each other (so the distance between them is 0 based on their commonly stated radii). At that exact moment, how does ...
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Understanding the Landau–Lifshitz–Gilbert (LLG) equation discrepancy in literature
Background, I am a masters student in microelectronics trying to perform some micromagnetic studies.
In some literature, the $\gamma$ in the LLG equation is said to be just the gyromagnetic ratio of ...
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Potential energies and Directions of angular momentums of an electron in $\rm H$ atom
I know in a Hydrogen atom, the electron revolves around the nucleus (proton) in a circular path. In addition, the electron spins about its own axis. Due to this spin, electron has a magnetic dipole ...
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Why compass needle doesn't precess about but aligns by magnetic field?
A magnetic dipole in magnetic field, precess about the axis of magnetic field. So why compass needle doesn't precess but lines up with magnetic field?
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An embarassing question about photon power, Hamiltonians, and converting units
I am a hapless experimentalist, and desperate for a bit of advice.
I am trying to do a spin-density calculation building on some of the ideas contained in this paper. In brief, it's describing a ...
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Gyrating proton near magnetic pole of the Earth
Imagine a proton from space which approaches the magnetic pole in the Northern hemisphere of the Earth. The proton spirals around the magnetic field lines. The $\vec{B}$-field is stronger near the ...
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The force on a magnetic dipole in a non-uniform magnetic field
Let's say there is a non-uniform magnetic field $B=(0,0,z)$ (i.e. the field is parallel to $z$-axis and the amplitude is linearly changing along $z$-axis). If there is a current loop (=magnetic dipole)...
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Force experienced by magnetic dipole from a current wire loop
I'm trying to figure out how I can calculate the force experienced by an object that has a magnetic moment from a circular loop of wire carrying a current $I$.
The loop of radius $R$ is located at the ...
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Working of MRI in detection of tissues for imaging
why we consider the rotational axis of proton under the action of magnetic field in MRI not electron?
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Deriving the Bleaney-Bowers equation from statistical mechanics
I've been recently reading about the derivation of the Bleaney-Bowers equation from Van Vleck paramagnetism and I am looking forward to derive it but using a statistical mechanics formalism instead.
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Classical dipole-dipole interaction in iron
I've been reading about the classical magnetic dipole-dipole interaction and I'm wondering how it would work in a ferromagnet element like iron (theoretically under the assumptions I will write below)....
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What will happen if I pass Current through Permanent bar Magnet?
Following the Picture below,
If I Conduct current through Permanent magnet Bar and hold the battery still. Will the magnet move in any direction ? Thank you.
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What is the secret behind the striking similarity between a quark pair and a bar magnet?
If one tries to split a pair of quark and an anti quark, one ends up with two pairs, in the same way, when one tries to break a magnet in half, one end up in the same way with two magnets, so is this ...
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Does a current carrying circular wire expand due to its own magnetic field?
Here is a thought experiment:
Since two parallel current carrying wires repel each other, does the same hold true for any element of a circular current carrying wire and thus the wire expands radially ...
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In what proportions is magnetic moment caused by spin and orbiting of electrons?
(What Im basically trying to understand is what causes magnetism, but this is a specific bit of that discussion)
In all discussions of this topic I hear about magnetic moment of electrons due to them ...
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How to calculate the magnetic field produced by an electron spin?
A circular coil carrying current has a magnetic moment associated with it and it produces magnetic field. A electron spin also has magnetic moment associated with it. Hence it should also produce ...
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Antenna as a heat exchanger in the magnetocaloric effect
Consider a refrigerator based on the magnetocaloric effect.
During the adiabatic demagnetization stage that starts at $T_h$ and bias field $H=H_{max}$ going to $H \to 0$ the magnetic dipoles relax and ...
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How to calculate the Force between a magnet & an induced dipole? [closed]
https://www.youtube.com/watch?v=xTwDZJG_W9w
In this video at 9:12 it details the potential energy of an induced dipole
Specifically
$$U=-mBcos\theta=(\frac{\chi V}{\mu_0}B)Bcos\theta$$
&
$$F_z=\...
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