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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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Force on current carrying loop due to non-uniform magnetic field

I was been taught that when there is a non-uniform magnetic field then the Force on a current carrying loop with Magnetic Moment M is F = M(dB/dx) where B is magnetic field. I can't get hold of this ...
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3 magnetic scalar points along a 1D axis of 1m. Using interpolation, how many additional data points needed for certain accuracy (statistical errors)? [closed]

On outdoor magnetic field surveys we're using a two fluxgate (vertical magnetometer configuration), while walking, spacing 1m. Since we're quite unhappy with our results, we now want place more ...
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What exactly is intensity of magnetization and magnetic field intensity?

What is intensity of magnetization (I) and magnetic field intensity (H)? What is the difference between them? I saw some similar questions but I either didn't understand the answers or I understood ...
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Linear approximation of the magnetic dipole field

Summary: using 3 angles to represent a magnetic dipole's orientation is redundant because the rotation around the $z$-axis of the dipole does not change the magnetic field, there are only 2 DOFs for ...
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Internally, what defines whether a material is magnetically hard or soft?

I know that magnetically hard materials hold magnetic fields (magnetic moment alignment) for longer, while soft metals do not. However, what, internally, causes these properties to arise?
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Magnetic moment of a paramagnetic cylinder

I am currently struggling with a problem where I have to calculate the magnetic moment $M$ of a cylinder of radius $R$ and height $h$ made up of a paramagnetic material (aluminium) and under a ...
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Magnetic moment of two electrons

For two electrons in the sate with S=1 and Sz=0, do we have a magnetic moment? Because the spin on the z axis is zero, thus if we couple it with a magnetic field on the z-direction we get zero.
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How to derive $V = -\textbf{m}\cdot \textbf{B}$? [closed]

Why is the potential energy of the magnetization $\textbf{m}$ in an induction magnetic field $\textbf{B}$ given by $$V = -\textbf{m}\cdot \textbf{B} \text{?}$$ I don't understand how to start from any ...
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Can hydrogen aquire magnetic moment?

Is the orientation of the electron inside its orbit around the proton inside the hydrogen atom dependent of the proton spin orientation... (as the spins of the two particles are cancelled out.)So if ...
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What is the physical meaning of the torque term involving the magnetic displacement force?

In Zangwill's Modern Electrodynamics the magnetic torque is derived in Eq. 12.63 to be \begin{equation} \mathbf{N}(\mathbf{r}_0) = \mathbf{m} \times \mathbf{B}(\mathbf{r}_0) + \mathbf{r}_0 \times \...
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Magnetic Field on a point in a current carrying wire

Current carrying wire produces a magnetic field around it, we all know that. A circular wire carrying current produces a magnetic field around it due to the flow of electric charge. This phenomenon is ...
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How does the polarity of the magnet changes when flipped upside down? What happens to the direction of magnetic domains and magnetic line of force?

Imagine you have two flat bar magnet with dimensions as $L \times B \times H = 100 \times 50 \times 5$ each. The $B \times H$ side of magnet 1 is facing the $B \times H$ side of the magnet 2. And let'...
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Why is Magnetism at the centre of a bar magnet zero?

I have seen some sources saying "Magnetism at the centre of a bar magnet is zero." and Some sources say "Magnetic field at the centre of a bar magnet is zero." Please help me ...
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Why can we calculate force on a dipole from torque?

In the Feynman lectures he derives the (mechanical) energy of a dipole $$ U = -\boldsymbol{\mu}\cdot \boldsymbol{B} + \mathrm{constant}$$ by considering only the torque on it in a uniform field. He ...
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Confusion regarding magnetic moment

Is it possible to have a magnetic configuration without a north and a south pole? My school textbook says that it is possible, as in the case of toroid and a wire carrying current. Now, the ...
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Can magnetisation component along a specific direction be measured by a magnetometer?

In a magnetometer, like VSM, we measure the magnetisation of the sample which is the net magnetisation. Is it possible to measure the component of the magnetisation along a specific direction? If yes, ...
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What is the force exterted on a Iron cylinder when expsed to an Magnetic Field

is there a way to find the approximate force exerted on a iron cylinder of dimensions (height 1cm, radius 0.5 cm) when it is placed in a magnetic field (Generated by a solenoid). I am trying to make a ...
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Magnetic moment of an silver atom

Image from Sakurai, Modern quantum mechanics. Question: Why $\partial_z(\mu\cdot B)\simeq\mu_z \partial_z B_z$? it's because $\mu_z$ is constant with respect to the $z$-axis? thanks.
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Hysteresis curves of a ferromagnet magnetized below saturation

I am confused about the qualitative behavior of ferromagnetic materials. Referencing the diagram below, I understand that magnetizing a ferromagnet from point A to point C (its saturation ...
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Magnetization current when two magnets are brought together and the Lorentz force law

Suppose we have two ferromagnetic objects constituting two permanent magnets. A classical way to think of the two magnets repelling/attracting each other would be by ascribing bulk and surface ...
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How strong of an MRI machine would be able to kill a person?

Previous title: How strong of a magnetic field could dissociate water molecules? (Changed as this is probably not possible) This is part of an attempt to answer the question 'How much MRI is enough to ...
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Motion equations of moving magnetic dipole in electric and magnetic field

I would like to find motion equations $m\frac{\text{d}^2}{\text{d}t^2}\vec{x} = -\vec{F}(\vec{x},\dot{\vec{x}},\vec{E},\vec{B})$ or Hamiltonian $\mathcal{H}$ or Lagrange function $\mathcal{L}$ of ...
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Estimate values of $g$-factor

I'm not sure I understand how to compute the gyromagnetic ratios. Here's what figured out: if we consider an orbiting charged point-like massive particle we can $\textit{classically}$ compute the ...
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Time for ferromagnet to align with magnetic field

A ferromagnet is inside a solenoid. When the current in the solenoid flips its direction, the solenoid magnetic field flips. As a consequence, the ferromagnet magnetization flips. What determines the ...
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Coexistence of a static electric and magnetic dipole

I have been trying to construct a charged object (not a conductor carrying any current) that can behave simultaneously as an electric and magnetic dipole and then calculate the electric and magnetic ...
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Force on Neodymium Magnet due to Magnetic Field from Electromagnet

I am a mechanical engineer currently in a university research program, and my project involves mixing bonded neodymium powder (Magnequench for those who are interested) into a polymer in order to ...
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Why don't the spin states of 47th proton in silver atom matters? [duplicate]

In the Stern-Garlach experiment the silver atoms are splits into spin up and spin down in a inhomogeneous magnetic field and latter the culprit is identified as the spin states of the 47th electron of ...
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Is the total magnetic moment of an object equal to the sum of the magnetic moments of the parts that compose it?

For example, given a spherical shell with charge $Q$ rotating on its axis, can I think of it as the composition of many concentric coils and integrate the infinitesimal magnetic moments $d\vec \mu$ to ...
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Magnetostatics problem involving dipoles

A while back I came across a problem in which I were to find the force of attraction between a magnetic dipole and a spherical iron ball (which is much smaller than the distance between the dipole and ...
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How great is the net force exerted on a superconducting material of a small size being subjected to an external uniform magnetic field?

Assume that we have a very tiny spherical or disk-like superconducting material that is subjected to an externally uniform magnetic field. I want to know if the net force that accelerates the ...
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Electric moment from the Pauli term?

The Pauli term is roughly given by $$M_{\mu\nu}F^{\mu\nu} = K\cdot E + J\cdot B$$ where $K$ is the boost and $E$ is the electric field and $J$ is the angular momentum and $B$ is the magnetic field. We ...
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Limit of solving the 1D Heisenberg chain to find the dynamics numerically

I am trying to simulate the dynamics of a 1D Heisenberg chain using Python. I am going step-by-step. There is an external magnetic field along +Z direction. At first we consider a single classical ...
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When modeling the magnetic field of an electromagnet array, how to take the interference between electromagnets into account?

When it comes to the magnetic field of an electromagnet array, all the papers and books I've read will give this equation: $$\mathbf{B}(\mathbf{P})=\sum_{e=1}^{n}\mathbf{B}_{e}(\mathbf{P})=\sum_{e=1}^{...
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Is there any way to detect localized magnetic field change in a magnetic material or powdered magnetic material?

Hi I was wondering if there was any way to detect localized magnetic field change within either bulk magnetic material or within like powdered magnetic material. The application we are looking for is ...
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How does the magnetic field of an electron compare to the magnetic field produced by a bar magnet? [duplicate]

We are currently studying Moving charges and magnetism in school and we learned that moving charges produce magnetic field and that magnetic dipole moments also produce it.However, magnetic monopoles ...
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Potential energy of a permanent magnet

A friend and I had a discussion about the potential energy of a permanent magnet, and we want to find out which of our views is right, but we can't seem to find information to confirm/disprove either ...
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Why atom with unpaired electrons is paramagnetic?

I know when electron spins are exposed to a magnetic field, they align so that their moments are parallel to the field. But why is there no paramagneticity for paired electrons? The book says it's ...
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Correct form of magnetic energy: $H dB$ vs $-B dM$

I found two different expressions for the magnetostatic energy density stored in magnetic materials. Avoiding vectorial notation, these read as: $dU=H dB $ $dU=-B dM$ It appears that the two are ...
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Orientation of Magnets in Paramagnetic Substances

We know that electrons can act as magnets and are responsible for the properties of para, diamagnetism, etc. In particular, paramagnetic and ferromagnetic materials are permanent magnets due to the ...
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Has the Stern-Gerlach experiment now been carried out with free electrons or protons instead of silver atoms? [duplicate]

At least, why not try with protons, they are much heavier and at the end, any deflection from Lorentz force will not overshadow the Stern- Gerlach phenomenon. But the question is still, was such ...
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Is there any measurement of electron spin that doesn't involve magnetic moment?

So the way to measure electron spin is to split the beam with a magnet to obtain two beams. Essentially what gets measured is magnetic moment, that is later interpreted as the direction of spin ...
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Tunneling lowers the energy of a ground state superposition of spins up and down in the quantum Ising model

Considering an Ising model in the quantum scenario in quantum spatial dimension d=1 (that corresponds to classical D=2=d+1 dimension). Starting with the Ising model hamiltonian under the approximation ...
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$(g-2)/2$ The anomalous magnetic moment [closed]

Does anyone know how to calculate the anomalous magnetic moment of the muon? The Fermilab result is 3 standard deviations from the standard model calculated value. Quantum electrodynamics to 10th ...
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What is the relationship between the distance of a current carrying wire and a dipole magnet's magnetic field strength?

For school, I'm doing this experiment where I measure the change in magnetic field strength, between a magnet and a current-carrying wire as a function of the distance. Online after doing some reading,...
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Problem with derivation of $U_B=-\mu \cdot \vec{B}$

I'm trying to prove that $U_B=-\mu \cdot \vec{B}$, but I keep running into an annoying dead end in my proof (a note about the notation my course's instructor uses: $\mu$ = magnetic moment, $NIA \hat{n}...
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Obtaining Current From Quantum State of 3d, assumed hydrogen atom

So I've been banging my head against this problem for a while and I genuinely have no clue how my answer is differing than the one provided to me and while I'm not usually the type to ask such a thing,...
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What exerts torque on a pulsar? [duplicate]

I'm modeling a pulsar as a rotating compact body with frequency $\omega(t)$, and magnetic dipole moment misaligned from the axis of rotation by angle $\chi$. It's straightforward to calculate the ...
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How does QED describe the electromagnetic scattering between two neutral fermions?

Fermions with no electric charge may carry magnetic moments e.g., the neutron. Since particles with magnetic magnetic moments interact, they're expected to scatter off each other electromagnetically. ...
Solidification's user avatar
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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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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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