Magnetic moment Definition and 181 Threads

The magnetic moment is the magnetic strength and orientation of a magnet or other object that produces a magnetic field. Examples of objects that have magnetic moments include: loops of electric current (such as electromagnets), permanent magnets, elementary particles (such as electrons), various molecules, and many astronomical objects (such as many planets, some moons, stars, etc).
More precisely, the term magnetic moment normally refers to a system's magnetic dipole moment, the component of the magnetic moment that can be represented by an equivalent magnetic dipole: a magnetic north and south pole separated by a very small distance. The magnetic dipole component is sufficient for small enough magnets or for large enough distances. Higher-order terms (such as the magnetic quadrupole moment) may be needed in addition to the dipole moment for extended objects.
The magnetic dipole moment of an object is readily defined in terms of the torque that object experiences in a given magnetic field. The same applied magnetic field creates larger torques on objects with larger magnetic moments. The strength (and direction) of this torque depends not only on the magnitude of the magnetic moment but also on its orientation relative to the direction of the magnetic field. The magnetic moment may be considered, therefore, to be a vector. The direction of the magnetic moment points from the south to north pole of the magnet (inside the magnet).
The magnetic field of a magnetic dipole is proportional to its magnetic dipole moment. The dipole component of an object's magnetic field is symmetric about the direction of its magnetic dipole moment, and decreases as the inverse cube of the distance from the object.

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  1. L

    Calculate the magnetic moment of a rotating sphere

    Ich wäre Ihnen sehr dankbar, wenn Sie sich meine Lösung der folgenden Übung ansehen: A sphere with radius ##R ## is spatially homogeneously loaded and rotates with constant angular velocity ##\vec{ \omega}## around the ##z ## axis running through the center of the sphere. Calculate the...
  2. ergospherical

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  3. C

    I Is the magnetic moment of a hydrogen atom not equal to Bohr's magneton?

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  4. dextercioby

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  5. K

    I Definition of magnetic moment in quantum mechanics

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  6. Anmoldeep

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  7. patric44

    Why the Stern-Gerlach experiment didn't detect the L?

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  8. M

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  9. G

    I Electron's magnetic moment

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  10. G

    How to get the magnetic moment for this loop?

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  11. TheBigDig

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  12. JD_PM

    Finding a method to compute the magnetic moment of an even-odd nucleus

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  13. H

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  14. M

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  15. R

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  16. K

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  17. Edge5

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  18. Javier Lopez

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  19. Javier Lopez

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  20. thee qs

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  21. T

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  22. M

    Finding Magnetic Moment from Pull Force

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  23. N

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  24. N

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  25. C

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  26. patrickmoloney

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  27. WeiShan Ng

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  28. C

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  29. Arman777

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  30. O

    I Calculate the Dipole Moment of an object

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  31. S

    How Do You Calculate the Magnetic Moment and Torque of a Rectangular Loop?

    Homework Statement A 15-turn rectangular loop of wire of width 10 cm and length 20 cm has a current of 2.5 A flowing through it. Two sides of the loop are oriented parallel to a uniform magnetic field of strength 0.037 T, and the other two sides are perpendicular to the magnetic field. (a) What...
  32. J

    I What does the magnetic moment of a particle depend on?

    Every magnetic object has a magnetic moment. From electrons to molecules, to even planets. But my question is, what determines how much of a magnetic moment a quantum object has? I'm not sure if "how much" is the right word for it. What determines the "quantity" of a magnetic moment of a...
  33. J

    B Does an electron's position collapse when measuring g factor?

    https://link.springer.com/chapter/10.1007/978-3-540-39664-2_1 http://iopscience.iop.org/article/10.1088/0031-8949/1988/T22/016/pdf In these two experiments done back in the 80's, electrons were trapped inside a penning trap for long periods of time. They were measuring the ratio of the magnetic...
  34. P

    Neutron scattering - determing the magnetic moment for MnO

    I'm told that the MnO crystal resembles in structure that of NaCl (FCC) with lattice constant a, and am first asked to write a general expression for the position vector Rj of the ion j in the unit cell of MnO. I am then asked to find the vector K for MnO in order to use the relation...
  35. TheSodesa

    A gyromagentic ratio for a cylinder

    Homework Statement In classical physics, a system's magnetic moment can be written like so: \mu = g\frac{Q}{2M}L, where ##Q## is the total charge, ##M## is the total mass of the system and ##L## the angular momentum. a) Show, that for a cylinder (##I = \frac{1}{2}MR^2##) spinning around its...
  36. P

    Induced Magnetic Moment (vector) vs. Induced EMF (scalar)

    When I induce magnetic flux through a closed loop, I should expect the lines of flux produced by current in that loop to oppose the change of flux through that loop. But what happens when that loop, say a rectangular loop, is curved into the shape of the letter J (like a candy cane) and my flux...
  37. Sudhir Regmi

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    I read that the stoichiometric half-metallic compound has integer spin moment. For this, n(up)-n(down) should be integer. Since n(up) +n(down) is always integer, either n(up) or n(down) should be integer to make total spin moment integer. I could not understand how the presence of energy gap in...
  38. pac134

    Torque upon a rotating magnetized body

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  39. K

    A Calculation of magnetic moment of an atom in the compound

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  40. T

    Does a Magnetic Moment μ exist for any closed current loop?

    I'm asking the above question as I imagined a current loop made out of a curving wire that cannot fit into a flat plane. Where does the direction of μ point then? Also, is there only one μ value for any current loop, independent of the chosen axis of tilting? Or can a current loop have...
  41. W

    Non-uniform magnetic fields and magnetic moment

    Hey all, I'm having some issues with electromagnetism here. Let's say we have a particle with magnetic moment ##\vec{\mu} = \mu_0 \hat{x}## and magnetic field ##\vec{B(x)} = B_0 \frac{x}{a} \hat{x}## where ##\mu_0,B_0,a## are constants. If we assume that the magnetic field ##B_0## is far, far...
  42. H

    Relation between torque and magnetic moment

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  43. D

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  44. C

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  45. F

    Magnetization (M) / magnetic moment (m) of NdFeB?

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  46. pbutter

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  47. E

    Magnetic field components of a circuit

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  48. JGBuck94

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  49. 1

    Deriving the magnetic moment of a specimen in a given magnetic field

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  50. Titan97

    Find spin only magnetic moment of [Fe(H2O)5NO](2+)

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