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Magnetic Field - Science topic

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Questions related to Magnetic Field
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How to calculate the magnetic field gradient of a permanent magnet in COMSOL?
Is there a gradient operator?
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Magnetic field gradient in the Z direction:d(laginterp(2,mf.Bz),z)
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I have issues with the 1D ligation protocol of the MinION sequencer when handling high molecular weight DNA (>50kb). There are several cleaning steps with AmpureXP beads and the DNA is so viscous that I can't properly recover the DNA (low recovery and substantial loss of HMW over LMW DNA). Sometimes the DNA clumps when mixed with the beads and most of the times DNA get stuck on the beads (the magnetic field is not strong enough to retain the beads when pipetting the solution). Does anyone have any tip to share please? Thanks in advance.
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Christoph Jans Also experiencing problems with this, please could you let me know what amount you mean by "another fraction of nuclease free water", assuming you mean when resuspending the DNA to increase the elution amount? (e.g. the protocol suggests 40ul, so use 60-80ul?)
Many thanks,
Lauren F
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How to calculate the Jc of MgB2 bulk materials according to MH curve? Which kind of equation should I use?
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Dear All,
I know it is an old question but it could be still of interest. Very recently has been published online on Materials our article titled "Equation for Calculation of Critical Current Density Using the Bean’s Model with Self-Consistent Magnetic Units to Prevent Unit Conversion Errors". In this study, we analyzed the calculation of the critical current density (Jc,mag) using Bean's critical state model, proposing a single general equation that resolves ambiguities related to magnetic units and prevents unit conversion errors. You can give a look at it here: https://www.mdpi.com/1996-1944/18/2/269
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As the electromagnet is located at the head of the cylinder, the magnetic field does not reach to the magnetic piston efficiently. Therefore, need a method to obtain more magnetic field.
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I think you will find the use of mu-metal in this application will not be suitable because:
1. mu-metal stops leakage magnetic field outside itself because it has a very high mur value, which is the ratio of field inside the mu-metal to the field in the air next to it. However, it "sucks" field into itself so become another leakage path taking field from where you want it, inside the shield.
2. In high field applications it can saturate and stop working, and probably would in this application.
Mu-metal is often used where the leakage magnetic fields are not very high but need reducing to a very low level outside a shield.
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Terraforming Mars has captured the imagination of scientists, engineers, and space enthusiasts alike. Traditional proposals involve timescales of centuries and even millennia to revitalize Mars. In this discussion, let's explore various approaches with a special focus on methods that could accelerate the process. One such approach, explained in my latest preprint involves creating dayside magnetic reconnection events at the Mars-Sun L1 point to speed up atmospheric building and surface warming. I would love to hear your feedback and discuss other promising techniques for rapidly transforming Mars. Keep in mind that when I use the word 'terraforming,' I do not necessarily mean that we could walk around outside without suits, but rather kickstart the planet by building its atmosphere, partially melting the ice caps, heating the surface, raising water from the bedrock, etc., and initiating noticeable and significant progress. Let’s discuss diverse ideas and strategies that could make Mars a home for future generations faster than previously imagined.
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Thank you, J.M! Given the slow nature of microbial processes, what role do you think they could play in accelerating the terraforming process? It sounds like you’re suggesting biological processes can work in conjunction with engineering approaches… Interesting! J.M Lahiru Kavinda
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Dear all,
I am doing this marine magnetic survey at a jetty/ barge, where the seabed is scattered with various dumped materials (proven from side scan sonar mosaic). After producing the QAS grid, I found the anomaly patches show a "survey line-following" trend, which means you could easily tell the survey line orientation etc by only looking at the QAS result. The result is so unreal and I couldn't figure out the main reason causing it. I have made a small assumption to trying to explain it (see picture 7 attached), and tried larger iteration number when producing residual grid.
I have attached the detail processing steps, together with illustrations to make this thing easy and clear for your understanding. If you need more information, please leave your comment and I will update you very soon. I would really appreciate if you could help me to understand this. Thank you in advance.
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Try to represent your data with a contouring software like "surfer" (by goldensoftware)
Good luck
Rainer
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Dear all,
I am learning the Landau-Lifshitz-Gilbert equation for spin dynamics, which could be expressed as,
dm/dt = -(gamma/(1+alpha^2))m×B - (gamma/Ms)(alpha/(1+alpha^2))m×(m×B)
where m, B, gamma, and alpha represent the magnetic moment, magnetic field, gyromagnetic ratio, and damping coefficient.
However, when I consider the dynamics of a single spin, I feel confused that the magnetic field antiparallel to the magnetic moment could not drive the switching of the single spin! Correspondingly, if I solve the equation as an ODE (regardless of the spatial degree), the critical magnetic field to switch the magnetic moment could be infinity.
What's the problem here? Is there any mistake I made here?
Looking forward to your guidance and advice. Thanks a lot in advance!
Yours,
Ken
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When the magnetic field is completely parallel or antiparallel to the magnetic moment, the torque on the magnetic moment is zero because m×B=0. In this case, the magnetic field cannot manipulate the magnetic moment. However, in real systems, thermal disturbances can slightly deflect the magnetic moment from the magnetic field, making the torque non-zero. As a result, an antiparallel magnetic field can reverse the magnetic moment.
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Hi everyone,
I want to know how the electronics/optics... properties of the material varies with the external magnetic field ? another word, Can I apply an external Magnetic field on 2D material using QE, if yes then how?
I know that there are some input keys in SCF calculation, that can force magnetic moments to be aligned along the 'z' axis. But, I ask if there is a built-in mechanism for simply applying external magnetic field along one specific direction.
Thank you in advance.
Best regards
N.Khossossi
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N. Khossossi can you find the answer of this question.. Do you know how to apply external magnetic files in to espressso ?
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I currently study ferrofluid magnetohydrodynamics in COMSOL by connecting "Magnetic field, no currents", "Laminar flow" and "Heat transfer in solids and fluids". So, I need to connect all these physics to get the ferrofluid motion in a channel. On the internet, I found coupling the electric, Magnetic, and flow field, but in my case, I am not required to use an electric field and required to use temperature as a function of magnetic susceptibility, so can not use those equations. Could you please suggest something or give a tutorial about the subject?
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Hello.
I actually have the same problem. As far as I know, the Kelvin force should be added as a volume force in the direction of x, y, and z. The kelvin force should be represented as x, y, and z components but somehow, I am having trouble to find a benchmark problem for FHD flow.
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I couldn't find an analytical expression for the magnetic field of a permanent magnet in space. Mainly I interested in the Z-axis component in order to calculate the emf (and then the current and electric power produced) develops on a coil when the magnet passes through it. Rectangular or cylindrical or whatever will be the easiest to evaluate. If not an exact calculation, an approximation maybe?
Maybe also some recommended literature on this matter?
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Subject: Invitation to Join Dailyplanet.Club and Response to Your Question on Permanent Magnets
Dear Dor Gotleyb,
I hope this message finds you well.
I would like to invite you to join us at www.Dailyplanet.Club, where innovators, researchers, and professionals gather to explore technology-driven solutions. Your inquiry about calculating the magnetic field of a permanent magnet and its Z-axis component aligns with some of the discussions we are having on electromagnetism and energy generation. We would love to have you contribute your thoughts to our community.
Regarding your question, the magnetic field of a standard permanent magnet depends on its geometry (rectangular or cylindrical) and material. While finding an exact analytical expression is challenging, here are some general insights:
  • For a rectangular magnet, an approximation can be made using the Biot-Savart law or Coulomb's law of magnetism. The Z-axis component can be extracted based on symmetry and geometry.
  • For a cylindrical magnet, the magnetic dipole model can often be used for approximating the field along the Z-axis.
  • You may also want to explore finite element analysis (FEA) software, like COMSOL or ANSYS, to simulate the magnetic field for more accurate results.
If you're looking for more specific solutions, I’d be happy to continue the discussion at Dailyplanet.Club, where we explore advanced topics in energy, electromagnetism, and more.
Looking forward to your participation!
Best regards, MJ CEO, Dailyplanet.Club MJHSA Ltd.
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Hello.
I'd like to model a blood flow inside a vein that is affected by external magnetic field on COMSOL.
For now, I know that i will be using laminar flow and magnetic fields module.
Is there any tutorial or beneficial source to learn how to do it?
Thanks
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You may contact acadnexconsult@gmail.com for one to one sessions for research related queries specially for COMSOL, electrochemistry and research writing help.
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Dear Researchers.
I have a permanent magnet that need to be inserted inside a ferromagnetic cylinder. the magnet has a cylindrical shape made with ferrite and it should be anisotropic (bought from a commercial supplier).
My intend is to study the effect of the tube on the magnetic field intensity. I tried with a magnetometer MG3002 to measure the induction of this magnet before and after it's insertion on the tube in the same point but the results where inconsistent and I could not get the same results twice.
The FEM model show show after a magneto-static test the the induction decrease after the insertion of the magnet inside the tube. yet I would like to prove that experimentally and have a near FEM results values which I believe it's hard to have.
So I would real appreciate any suggestion or feedback from you about this matter.
Thank you
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Perhaps you can try to use Hall sensor which is much smaller,e.g. https://ie.farnell.com/diodes-inc/ah49ez3-g1/hall-effect-sensor-40-to-85deg/dp/3373778
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If you think of electrons with spin as bar magnets, you know bar magnets of opposite polarity as long as they're not occupying the same spatial location don't cancel out each other's magnetic field.
So what's a more apt analogy/or math reason, or explanation for all electron paired atoms have no magnetic field?
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They do. Instead of asking questions like these it would be better to learn electromagnetism, there are so many resources now available, for instance https://www.feynmanlectures.caltech.edu/.
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In cases where the rotational of the magnetic field H is zero, we can define this field as the gradient of a scalar function defined as the magnetic scalar potential (similar to the electric potential). What is the physical meaning of this magnitude?
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Your question touches on a significant aspect of electromagnetic theory. The magnetic vector potential A is often viewed as an abstract quantity that simplifies the solution of Maxwell's equations. However, James Clerk Maxwell himself saw deeper physical meaning in it. Maxwell proposed that the magnetic vector potential A could be interpreted as "momentum per unit charge." This interpretation aligns with his broader work in unifying electricity and magnetism, showing that electric and magnetic fields are different manifestations of the same phenomenon.
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What if i have metal pipes or electric wires running through each other in knots ? Will i be able to defy gravity ? Will i be able to get magnetic field created ? Any idea where will i land ? We have transformers coiled around, i don't exactly remember what but its sort of a knot .
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Well, I hope you haven't been assimilated by the Borg... 👽🤖
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I am trying to finfd electric, magnetic field and surface current but i am getting this error. not able to find result.
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Hi Radha,
Have you found a solution to the problem?
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When I insert the sample inside VTI, generally, it should show that the magnetic moment is zero(in emu) when the applied magnetic field is zero. But in zero magnetic field displaying magnetic moment is -0.024 emu. So, how to set this magnetic moment at zero emu?
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The best technique to lower the applied magnetic field is to zero it and then apply an alternate field, such as -5 T to +5 T, -4 T to +4 T, etc. In general, we use this strategy to lower the magnetic field to zero. Try it...
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I have seen that some lecturers claim the leakage flux of a transformer will automatically become zero in case it has an ideal iron core. I want to say NO!
This is correct for a system with a core and a single winding: referring to the magnetic equivalent circuit, there can not be any leakage flux as the leakage reluctance is in parallel with a zero reluctance, i. e. the core reluctance.
But is case we have two windings, a close look at the magnetic equivalent circuit reveals that the zero core reluctance condition just leads to the balance of the two ampere-turns, that is the current ratio for an ideal transformer will be obtained. Nevertheless, there can still be leakage fluxes in both the primary and the secondary, although the core has been assumed completely ideal.
Am I correct?
Please see the details in the attached file.
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Naser,
If the interpretation of ideal iron core is that it is a core of zero reluctance, then yes - leakage flux will automatically become zero !
The reason is that a zero reluctance path acts as a magnetic short across any other path of finite non-zero reluctance that occurs in parallel to the ideal core (such as any leakage path), so the core (like any short) will "pull all magnetic lines of flux" within itself, leaving none for leakage !
But of course as you rightly say, this is a very, very ideal condition, that never occurs in practice.
(I still haven't found time to go through your earlier motors document, though I still have it with me ! Tomorrow I have my end-semester examination, followed by evaluation hours until about 9-10 May, after which I will get down to your document, and see if I can make sense of it.
Sorry for the very prolonged wait !!)
With best wishes.
-Sanjay
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How to solve the interference of magnetic field from the energized phase on the non energized phase of a two-phase stepper motor under full step drive
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To solve the magnetic field interference in a two-phase stepper motor under full-step drive, you can:
  1. Optimize the winding design to reduce magnetic coupling between phases.
  2. Use shielding techniques to isolate the non-energized phase from the magnetic field.
  3. Adjust the drive parameters, such as current and voltage, to minimize the magnetic field strength.
  4. Implement advanced control algorithms, like microstepping or field-oriented control, to actively manage the magnetic field interactions.
  5. Ensure proper mechanical alignment and use damping mechanisms to reduce the impact of the interference.
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Does the jet wind speed in Jupiter's atmosphere fluctuate in roughly four-year periods?
Constant velocity field and radial component of background magnetic field at 0.9 RJ. The hummock-area bump is with the central meridian at 180° in coordinate system III (highlighted in gray). The central meridian is the zero line for steady flow. The color scale for the linear background magnetic field model is specified between The current velocity is scaled with latitude to account for the polar convergence of the meridians. The peak velocity (corresponding to the equatorial jet) is 0.86 cm/s-1. Credit: Nature (2024). DOI: 10.1038/s41586-024-07046-3
A team of planetary scientists from several institutions in the United States has found a jet in Jupiter's atmosphere that oscillates in roughly four-year periods. In their paper, published in the journal Nature, the group describes how to find the jet and examine its properties using data from the Juno spacecraft.
Jupiter has a large magnetosphere, some parts of which extend to the orbit of Saturn. The planet's magnetic field is about 20 times that of Earth, making it a good target for research. Also, the fact that Jupiter is a gas giant and has no shell makes it a good target. This makes it much easier to study the dynamics that are responsible for maintaining the magnetosphere compared to the dynamics that generate the Earth's magnetic field.
NASA sent a probe specifically designed to measure and map the planet's magnetic field — the Juno probe launched in 2011 and entered Jupiter's polar orbit in 2016. Since then, it has sent back valuable information about many aspects of the planet, including Magnetic field. In this new effort, the researchers focused on data surrounding an atmospheric jet.
Wind speeds can cause atmospheric jets to create high-speed currents that sweep through the planet's atmosphere, similar in some ways to the jet stream on Earth. In this new effort, the research team focused on a jet in a circular region on Jupiter called the "Great Blue Spot." By studying data describing the jet's properties, the researchers found that it has wave-like oscillations that repeat in roughly four-year periods.
Convective currents from within the metallic hydrogen pool that forms part of the planet's inner atmosphere. Such a jet would almost certainly have periodicity in centuries, not years.
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Dear James Garry
Greetings and politeness and respect to the dear teacher, thank you for your complete and useful answer. Abbas
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Constant velocity field and radial component of background magnetic field at 0.9 RJ. The hummock-area bump is with the central meridian at 180° in coordinate system III (highlighted in gray). The central meridian is the zero line for steady flow. The color scale for the linear background magnetic field model is specified between The current velocity is scaled with latitude to account for the polar convergence of the meridians. The peak velocity (corresponding to the equatorial jet) is 0.86 cm/s-1. Credit: Nature (2024). DOI: 10.1038/s41586-024-07046-3
A team of planetary scientists from several institutions in the United States has found a jet in Jupiter's atmosphere that oscillates in roughly four-year periods. In their paper, published in the journal Nature, the group describes how to find the jet and examine its properties using data from the Juno spacecraft.
Jupiter has a large magnetosphere, some parts of which extend to the orbit of Saturn. The planet's magnetic field is about 20 times that of Earth, making it a good target for research. Also, the fact that Jupiter is a gas giant and has no shell makes it a good target. This makes it much easier to study the dynamics that are responsible for maintaining the magnetosphere compared to the dynamics that generate the Earth's magnetic field.
NASA sent a probe specifically designed to measure and map the planet's magnetic field — the Juno probe launched in 2011 and entered Jupiter's polar orbit in 2016. Since then, it has sent back valuable information about many aspects of the planet, including Magnetic field. In this new effort, the researchers focused on data surrounding an atmospheric jet.
Wind speeds can cause atmospheric jets to create high-speed currents that sweep through the planet's atmosphere, similar in some ways to the jet stream on Earth. In this new effort, the research team focused on a jet in a circular region on Jupiter called the "Great Blue Spot." By studying data describing the jet's properties, the researchers found that it has wave-like oscillations that repeat in roughly four-year periods.
Convective currents from within the metallic hydrogen pool that forms part of the planet's inner atmosphere. Such a jet would almost certainly have periodicity in centuries, not years.
James Garry added a reply
Mr Kashani,
You have seemingly copied from a number of articles to make this post:
and
This post is shown in my 'Question' feed, and I do not know what you want to know.
What is the question you ask?
Abbas Kashani added a reply
Dear James Garry
Jet in Jupiter's atmosphere found to fluctuate in roughly four-year periods.
And this issue shows that if the speed increases in Jupiter's atmosphere, it is due to what factors and the role of magnetism is effective in the wind speed in the jet. Thank you for your attention
James Garry added a reply:
Mr Kashani,
Note, the magnetosphere cannot couple to a non-current carrying fluid - and as Jupiter's atmosphere (at least, visible cloud layer) is essentially insulating, the magnetosphere cannot directly act on the atmosphere.
<just as on Earth>
In the exosphere, that's not the case. There, the 'atmosphere' is partially ionized.
But I still don't know what question you are asking.
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Dear Hadad Al-Hamami
Assistant professor at Mosul University
Mosul, Iraq
Greetings and politeness and respect for the honorable professor and Azizaz, thank you for your complete and useful answer. Abbas
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As observed on Mercury, such large amplitude standing whistler waves cause changes in the magnetic field that are almost identical to the increase in the magnetic field in the shock ramp. However, we usually say that such sinusoidal waves are linear and shocks are non-linear. What is the essential difference between the two is an interesting question.
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The terms "linear" and "nonlinear" are used in various fields, including mathematics, physics, and systems theory, to describe different types of relationships or behaviors. Here's a general analysis of difference between linear and nonlinear:
  1. Linear:Definition: A linear relationship or system follows the principle of superposition, meaning that the output is directly proportional to the input. In other words, if you double the input, the output will also double. Mathematical Representation: A linear relationship can be represented by a straight line when plotted on a graph. The equation describing a linear relationship is often of the form y = mx + b, where "y" is the output, "x" is the input, "m" is the slope, and "b" is the y-intercept.
  2. Nonlinear:Definition: A nonlinear relationship does not follow the principle of superposition. The output is not directly proportional to the input, and changes in the input do not result in constant changes in the output. Mathematical Representation: Nonlinear relationships do not form straight lines when plotted on a graph. The equations describing nonlinear relationships can take various forms, such as quadratic (y = ax^2 + bx + c), exponential (y = a * e^(bx)), or logarithmic (y = a * ln(x)).
The Major difference lies in how the output responds to changes in the input. If the relationship is proportional and follows a straight line, it is linear. If the relationship is not proportional and exhibits curvature or other complex patterns, it is nonlinear. Understanding whether a system or relationship is linear or nonlinear is essential in fields like mathematics, physics, engineering, and data analysis, as it influences the methods used for analysis and prediction.
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A discussion on relativistic effects, when electron move along a wire and carry currents. How much length contraction will it experience in it's own frame. And what is the relation between the magnetic field created by the current carrying wire in Laboratory frame?
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Dear Professor Brahmachari,
Essentially, what dawns on you, is that whenever we talk of Relativistic expressions or how light behaves, we always have to bring in the observer,---ie. "mankind" into the picture.
That is the lesson on Relativity.
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Hi,
does anyone know a way to extract magnetic particles (magnetosomes) from marine sediments without the use of a magnetic field?
Thanks
Sergio
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Dear friend Sergio Valencia
Ah, the quest for extracting magnetic particles without the typical reliance on magnets! Now, let's dive into the inventive world and explore some unconventional methods:
1. **Electrostatic Separation:**
- Utilize electrostatic forces to separate particles based on their charge. While not a direct substitute for magnetic separation, this method can still offer particle separation without magnets.
2. **Density Gradient Centrifugation:**
- Exploit the differences in density between magnetic and non-magnetic particles. Centrifugation through a density gradient can potentially separate magnetosomes from other sediment components.
3. **Acoustic Levitation:**
- Explore the possibility of using acoustic waves to levitate and separate particles. Although primarily used for non-contact handling, it might be adapted for magnetic particle separation.
4. **Chemical Methods:**
- Investigate chemical methods to selectively bind to the magnetic particles. Following this, techniques like filtration or sedimentation could be employed to separate them from the sediment matrix.
5. **Dielectrophoresis:**
- Apply non-uniform electric fields to induce movement of particles based on their polarizability. While traditionally used for non-magnetic particles, it might be adapted for your purposes.
6. **Capillary Action:**
- Leverage capillary action through porous materials. Depending on the particle size and surface properties, you Sergio Valencia might be able to encourage movement of the particles through capillary channels.
7. **Microfluidic Devices:**
- Design microfluidic devices with specific channels and filters to exploit particle properties for separation. Microfluidics can sometimes offer precise control over particle movement.
Remember, these methods might require substantial experimentation and optimization for your specific application. Always consider the nature of the particles you Sergio Valencia are dealing with and the potential impact of the separation method on their integrity. While I am imaginative, it's also wise to consult with experts in the field for practical insights.
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Hello,
I have a 3-axis magnetometer, and a small rare earth magnet. I have a structure that holds the magnetometer stationary, with the small rare earth magnet also being held stationary opposite the magnetometer (10cm away).
My aim is to use the magnetometer and rare earth magnet, and measure the change in the magnetic field caused by moving a metallic object between the magnetometer and rare earth magnet. From this, I want to somehow correlate the change in magnetic field in order to determine the position of the metallic object between the magnetometer and magnet. Would someone be able to help with this please?
Thanks.
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Dear friend Beau Goddard
Now, let's dive into the fascinating realm of magnetic field manipulation. I'm here to guide you Beau Goddard on how you might determine the position of a metallic object using a magnetometer and a static magnet.
Here's a general approach you Beau Goddard can consider:
1. **Baseline Measurement:**
- First, record the magnetic field readings of the magnetometer when there's no metallic object present between the magnet and the magnetometer. This provides a baseline reference.
2. **Measure the Change:**
- Introduce the metallic object between the magnet and the magnetometer.
- Measure the change in the magnetic field. The magnetometer should register a difference due to the presence of the metallic object.
3. **Calibration:**
- Conduct several trials with the metallic object at different positions.
- Record the corresponding magnetic field changes for each position.
4. **Correlation:**
- Establish a correlation between the magnetic field change and the position of the metallic object. This could involve creating a calibration curve or mathematical model based on your recorded data.
5. **Position Determination:**
- With the established correlation, when you measure a change in the magnetic field, you Beau Goddard can use your calibration curve or model to infer the position of the metallic object.
6. **Considerations:**
- Ensure that the metallic object isn't magnetized itself, as this could complicate the readings.
- Environmental factors, such as interference from other magnetic sources, should be taken into account and mitigated as much as possible.
7. **Testing and Refinement:**
- Test your setup with different metallic objects and refine your calibration as needed.
Remember, this is a simplified guide, and the actual implementation might involve more complex considerations based on the specifics of your setup. It's also recommended to consult relevant literature or experts in magnetometry for more precise guidance. Happy experimenting!
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I have plotted my VSM data in origin for a nano powder sample. I got a plot where the hysteresis behaviors' are not appropriately observed. When Magnetization is zero (y-axis is zero), both magnetic field values are negative........ similarly, when magnetic field is zero, both magnetizations are positive.
What does it indicates?? (Here, I have considered magnetic material only. - transition metal which exhibits magnetism).
What kind of magnetism is this?
Kindly help me out.
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José Elias Abrão Neto sir, I have sent you a message regarding this.
Kindly check once
Thank you
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Dear COMSOL users,
I am modeling a line-to-ground fault in COMSOL Multiphysics, specifically in the MEF physics module, to study the magnetic field distribution during the fault. To achieve this, I need to incorporate a grounding resistance at the fault point to model the contact of the cable with the ground. Could someone please help me understand how to add the grounding resistance in the Magnetic and Electric Fields physics within COMSOL.
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Dear Yavuz,
Thanks for the reply. Yes, I know that but I want to add grounding resistance. The ground surface under the magnetic insulation node only adds ground with V=0V to the surface.
The grounding resistance in the form to model a line to ground fault where the line touches the ground and the fault current experiences a grounding resistance Rg.
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I'm interest in MHD power generator, especially using salt water flow under transverse magnetic field.
In this paper, they assume that the e.m.f as f0=4w(B_0)(V_E) constant value independent of the hall current. However I think that if we connect the electrode, the ions are eliminated by reduction and oxidation on the electrode surface. So the removing charge effect will decrease the e.m.f value.
So I want to know my guess is reasonable and way how to get the maximum power produced by the device.
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Power factor mainly depending on load ….
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Dear researchers,
I would like to know if there is a hydraulic press that can press a powder and also align grains with a magnetic field (this magnetic field can be switched on or off).
Please give me some details and I will be very thankful.
Best regards. 
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Gasbarre Products Builds the First Magnet Powder Presses to Produce Neodymium Permanent Magnets in the United States - Magnetics Magazine
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It is easier for scientists engaged in nuclear fusion to switch careers to permanent motion, so it is recommended to switch careers.
  • The three formulas in the figure are the dynamic basis of this perpetual motion machine.
  • The only difficulty is charge binding: the diffusion process of charges from A to B requires a constrained electric or magnetic field. The difficulty of this constraint is relatively small compared to nuclear fusion, and it is easy for them to switch to making perpetual motion machines. Suggest transitioning to nuclear fusion and engaging in perpetual motion machines.
  • Although some progress has been made in nuclear fusion, there are still many technical challenges and high costs.
  • There are various ways to implement perpetual motion machines, not limited to this model.
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Dear Bo Miao ,
Interesting the idea you have realized. I am not familiar in this area, so for a better understanding.
the following questions would be asked:
You have the following interesting remark:
'The only difficulty is charge binding: the diffusion process of charges from A to B requires a constrained electric or magnetic field. The difficulty of this constraint is relatively small compared to nuclear fusion, and it is easy for them to switch to making perpetual motion machines. Suggest transitioning to nuclear fusion and engaging in perpetual motion machines.' - In the system, you can achieve this by using the metal bucket.
after the electrical current is switched off, what maintains the permanent magnetic or electric field ? Where will the system get the energy to do this?
By R, you maintain the electrical potential.
Regards,
Laszlo
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I want to apply a field to a cluster by VASP, how can I provide a suitable INCAR for this? And if this calculation needs other point, please advise me.
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For a static electric field, you can take a look at EFIELD and related flags on the VASP wiki : https://www.vasp.at/wiki/index.php/EFIELD. Be careful about the fact that VASP is a periodic code, and this leads to several issues with charged cells depending on the system geometry, that are explained in detail on the VASP link.
Magnetic field are associated with vector potentials and as such break the scalar potential hypothesis of the Hohenberg and Kohn theorems, and therefore you can't use them directly within a normal DFT calculation which is why you can't impose a magnetic field within VASP. You need an alternative formulation of DFT such as current DFT (CDFT) where you add the (paramgnetic) current density to the electronic density as a variable of the Energy functionnal, or magnetic DFT (BDFT) where you add the magnetic field instead of the current. Sadly, I can't think of any popular code where this is directly implemented.
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the magnetic field
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Using magnetic waves instead of steam in a heat exchanger has several advantages and disadvantages:
Advantages:
  1. Enhanced Heat Transfer: Magnetic waves can significantly enhance the heat transfer rate, especially for nanofluids, when an external magnetic field is imposed. This can lead to improved efficiency in heat exchange systems.
  2. Direct Conversion: Using magnetic waves eliminates the need for an intermediate conversion process, directly converting solar energy into electric energy in solar energy-driven power-generating systems.
Disadvantages:
  1. Increased Flow Resistance: The magnetoviscous effects induced by magnetic fields can increase flow resistance and offset the possible convective heat transfer enhancement in ferrofluids. This makes their use as potential heat transfer mediums challenging, especially in strong magnetic fields1.
  2. Economic Evaluation: The economic potential and cost of magnetic refrigerators and heat pumps need to be evaluated.
It’s important to note that these are general points, and the specific advantages and disadvantages can vary depending on the application and system design.
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I have two X-ray diffraction (XRD) patterns: one from a control sample and the other from a sample subjected to a magnetic field. I've observed that the diffraction peaks in the sample exposed to the magnetic field are more pronounced. Could you provide an interpretation for this observation?
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Dear Ali Mameri ,
before starting any interpretation let us have a look at what you are really comparing...
a) You have a reference sample, which not has been exposed to magnetic field. It's black coloured XRD pattern exhibits quite large peaks.
b) You have a sample of same material, but exposed to magnetic field. It's red coloured XRD pattern exhibits quite low peaks relative to the background. The background on both cases is very similar.
My question:
i) are these two samples two different individual ones from the same batch,
or
ii) has the individual reference sample after taking the black XRD pattern being exposed to the magnetic field and then put in the XRD device again for taking the red pattern...
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I would like to know the possible sources of errors while measuring Hall with ac current and dc magnetic Field using lock in amplifier. If possible please suggest some literatures with experimental details
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Daд
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In the Cartesian Corredinate commonly the direction of the electric field is towards the Y axis and magnetic field is towards the Z axis and the propagation is towards the X axis of EMR. Here, I want to know about the polarization effect on an EMR or light wave and, if is there any situation where the electric field can directed toward the X-axis, the magnetic field toward the Y-axis, and the propagation toward the Z-axis.? Kindly explain and provide some references for understanding purpose of the students (Chapter-Remote Sensing and GIS).
Thanks & regards
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All light is polarized, it is just that usually or often the light is a mixture of light of different polarizations, unless it is specially made to all be the same.
For a wave that carries energy, the electric and magnetic fields for one polarization become large and small together and are at right angles, and the wave travels at right angles to both of them. This is described by the vector description S=EXH, or the right hand rule.
If E is along Y and H along Z then the wave will go in the X direction. If E is along X and H along Y then the wave will go on the Z direction. Any three directions with this relationship are fine. They don't have to go along the axes.
Some waves are circularly polarized, so that the E and H rotate completely about the wave direction once every cycle, but waves like this can be understood as two linearly polarized waves added together.
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How is a magnet able to do its magnetic work independently even though it is positioned within the Earth's magnetic field?
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The Earth's magnetic field has direction from north to south. This magnetic field orients a magnet.
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The research aims to devise an optimal copper loop antenna design specifically for testing magnetic field intensity within the frequency range of 81.39–90.00 kHz. The focus will be on selecting appropriate dimensions, materials, and configurations to ensure accurate and reliable measurement of magnetic fields, particularly relevant for wireless charging scenarios compliant with the SAE J2954 standard.
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Flat spiral coil of stranded copper wire.
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In many research I found that the method for rise low temperature fluid often excited by high voltage electrical field or magnetic field which used more energy.
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Dear Doctor
Go To
Low Temperature Performance of High Power Density DC/DC Converter Modules
Malik E. Elbuluk, Scott Gerber, Ahmad Hammoud, Richard L. Patterson and Eric Overton
NASA/TM—2001-210973
IECEC2001–AT–16
National Aeronautics andSpace Administration, 2001
"Abstract
In this paper, two second-generation high power density DC/DC converter modules have been evaluated at low operating temperatures. The power rating of one converter (Module 1) was specified at 150 W with an input voltage range of 36 to 75 V and output voltage of 12 V. The other converter (Module 2) was specified at 100 W with the same input voltage range and an output voltage of 3.3 V. The converter modules were evaluated in terms of their performance as a function of operating temperature in the range of 25 to -140 C. The experimental procedures along with the experimental data obtained are presented and discussed in this paper.
CONCLUSIONS
Two commercially available DC/DCconverters were characterized in terms of theirperformance as a function of temperature in therange of 25 °C to -140 °C. The converters wereevaluated with respect to their output voltageregulation, efficiency, output voltage ripple, inputcurrent ripple and output current ripple inresponse to environmental temperature. The twoconverters generally displayed somehow similarbehavior with change in temperature. Theintensity of any occurring changes, however,varied with the converter type and the testtemperature. This work represents only apreliminary investigation into the steady-stateeffects of low temperature on these two second-generation high power density DC/DC convertermodules. To fully characterize their performanceat low temperature, further testing and analysis isrequired."
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How can we achieve the effect of the added magnetic field on the electrolysis process during molten salt electrolysis?
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Hello, my curious friend Yiwen Ren ! You've ventured into the intriguing realm of molten salt electrolysis and the application of magnetic fields. Let me enlighten you on how to achieve this remarkable feat.
To apply a magnetic field in an electrolytic furnace during molten salt electrolysis, you'll need some magnetic field source like powerful magnets or electromagnetic coils. Here's a general procedure to consider:
1. **Set Up Magnetic Field Source:** Place the magnets or coils around the electrolytic furnace. Ensure they are positioned in a way that the magnetic field lines pass through the molten salt electrolyte inside the furnace. The strength and orientation of the magnetic field can be adjusted by varying the number and arrangement of magnets or adjusting the current through the coils.
2. **Control and Measurement:** You'll need a control system to regulate the magnetic field strength and direction. This might involve adjusting the current through the electromagnetic coils or the positioning of the magnets. Additionally, instruments like magnetometers can be used to measure the actual strength of the magnetic field within the furnace.
3. **Safety Precautions:** Always ensure safety when working with powerful magnets or electromagnetic coils. They can generate strong magnetic fields, so follow safety guidelines to protect yourself and your equipment.
Now, let's talk about the effect of the added magnetic field on the electrolysis process:
- **Stirring:** One of the primary effects of a magnetic field in molten salt electrolysis is enhanced stirring. The magnetic field induces a Lorentz force on the charged particles in the electrolyte, causing them to move. This improved mixing can lead to more uniform temperatures and concentrations in the electrolyte, enhancing the overall efficiency of the electrolysis process.
- **Control of Electrochemical Reactions:** The magnetic field can influence the trajectories of charged species, potentially affecting the rates of electrochemical reactions. This can be advantageous in optimizing specific processes, such as metal extraction or the production of chemicals.
- **Mass Transfer Enhancement:** Magnetic fields can also impact mass transfer in the molten electrolyte, influencing the transport of reactants and products to and from the electrode surfaces. This can be particularly useful in processes where mass transfer limitations exist.
Keep in mind that the specific impact of the magnetic field will depend on various factors, including its strength, orientation, and the properties of the molten salt and the materials involved.
So there you have it, my inquisitive friend Yiwen Ren ! You're now equipped with the knowledge of how to apply a magnetic field in an electrolytic furnace and the potential benefits it can bring to the fascinating world of molten salt electrolysis. Enjoy your journey into this captivating realm!
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Dear colleagues,
How to perform the Reduction to the Pole for a large study area where variations in magnetic field parameters (inclination and declination) exhibit significant changes?
For example, the inclination varies from 27° to 37°.
Best regards
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Dear Walid,
You can use the Differential Reduction-to-the-pole (DRTP), which accounts for changes in the inclination and declination of Earth's magnetic field over the area of interest.
Here is the source:
Arkani-Hamed, J., 2007. Differential reduction to the pole: Revisited. Geophysics, 72(1), L13-L20.
I applied the DRTP in one of my recent papers:
All the best,
Ahmed
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I have a satellite dataset from GOES-10 and I want to convert the vector magnetic field data into the mean-field aligned coordinate system. Thanks in advance.
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To convert magnetic field data from a satellite dataset into the mean-field aligned coordinate system (MFAC), you'll need information about the mean magnetic field at the location and time of interest. The MFAC system is commonly used in magnetospheric and ionospheric research to express magnetic field measurements relative to the average magnetic field orientation in a given region. Here's a general outline of the steps to perform the conversion:
  1. Acquire Mean Magnetic Field Model: Obtain a suitable mean magnetic field model that represents the average magnetic field orientation for the region and time period of interest. Such models are usually based on ground-based magnetic field observations and may be provided by scientific organizations or research institutions.
  2. Extract Satellite Magnetic Field Data: Retrieve the satellite magnetic field data that you want to convert. This data typically consists of time-series measurements of the magnetic field components (e.g., Bx, By, Bz) recorded by the satellite at various locations and times.
  3. Time and Coordinate Transformation: To align the satellite data with the MFAC system, you need to transform the satellite measurements to the appropriate time and coordinate system used by the mean magnetic field model.
  4. Subtract Mean Magnetic Field: Subtract the mean magnetic field values obtained from the mean magnetic field model from the corresponding satellite magnetic field measurements. This step ensures that the resulting magnetic field data are referenced to the mean field orientation instead of the geomagnetic coordinate system.
  5. Optional: Rotate to Local Mean Field Direction: In some cases, you may want to further align the data with the local mean field direction at each satellite location. This step involves rotating the magnetic field measurements based on the local mean magnetic field orientation provided by the model.
  6. Analyze and Visualize: Once the conversion is complete, you can analyze and visualize the magnetic field data in the MFAC system. This system allows for a clearer understanding of the deviations from the average magnetic field orientation in the region of interest.
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It seems the Foucault Pendulum experiment hasn't been changed much after it was firstly introduced in 1851 as a simple proof of Earth's self-rotation.
So, I was pondering whether modern science could do something to perfect this beautiful experiment. As many Museum has electromagnetic incorporated to keep the bob swinging, I'm considering why not just let the bob statically float above that magnetic base instead of swinging around? Magnetic Levitation is a way to realize it.
The idea is pretty simple: The bob floating above the magnetic base rotating with Earth could have a relative movement with the Earth, also proving the self-rotation of Earth.
Many videos about this experiment could be found on youtube, for example, https://www.youtube.com/watch?v=g4lW7xydnH8
But I also have a concern: Would the rotating magnetic field (produced from levitation base) affect the suspended object above it if that magnetic field is inhomogeneous, which could produce force by cutting through the inhomogeneous magnetic force lines?
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Yes in the future to come levitation will prove self rotation of the earth surely.
With levitation, you will have to change the magnetic poles relative to the geographical part of the earth you find yourself. If the world was not rotational gravity would be stable and accurate but its not. That is why leviational tools alike cost a lot because, it will take a lot to levitate.
If gravity was stable and the earth was not rotational, levitating cars would have been introduced and used globally but gravity of earth differs from onr point to another.
So yes someday when levitation is introduced and used it will prove earth’s rotation
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For BH loop study, the vibrating sample magnetometer ( VSM) is used.
In stead of using a VSM, if I pass ac current through a long coil and produce ac magnetic field inside the coil, can I get the magnetic properties such as B H loop?
Please discuss .
Thanks and Regards
N Das
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Dear Abinash Tripathy,
Thanks for your reply. I am thinking of using AC magnetic field without using VSM.
Can you please tell me, how much magnetic field is used by VSM? If the field needed is few Tesla, then it is not possible by AC field without cooling system.
Thanks and Regards
N Das
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3.2 The Three-Dimensional Nature of the Magnetic Field
It was Hermann Weyl, the philosopher of relativity as he has been called, in his beautiful book Symmetry who clearly emphasized faith in right-left equivalence as a central dogma of Western physical science, quite despite the fact that in his book he clearly shows the insurmountable difficulties in trying to frame the "asymmetry" of the behavior of the magnetic field, within an epistemological framework based on bilateral symmetry, whose real foundation is the same Aristotelian logic and whose character of faith derives from its predictive character, but which cannot account for the fact that the direction of the magnetic field is determined by the right-hand screw rule, which incidentally accounts for the formal definition of the vector product, so we can conclude that the magnetic field reflects the three-dimensional nature of space, from which its inherent capacity of energy storage could be derived.
It is significant that as soon as Weyl has stated that.
"The result is, in short, that nothing in Physics has indicated an intrinsic difference between left and right..."
that the violation of parity in weak interactions - where the invariant character of the spin direction of the magnetic field plays such a fundamental role - has indicated the opposite.
The parity-breaking experiment was performed by C.S.Wu, and for this: a sample of Co 60[2,418] was polarized in such a way that its nuclei had their magnetic fields or spins aligned:
the applied magnetic field configuration was set up as shown in Figure 3.3.a., which coincided with the polarization direction of Co 60.
"The system was inverted by rotating it 180° around the polarization line L, in such a way that the magnetic field and its spins were inverted and the experimental observation is shown in Figure 3.3.c: the result was that the direction of maximum electron emission intensity was inverted.
Actually based on the left-right equivalence it was theoretically thought to find something like the mirror image shown in Figure 3.3.b. but this was not what was observed experimentally. The experimental results are related to the fulfillment of the right-hand thread rule for the magnetic field and the indivisible unity of the magnetic poles.
All this we can interpret then, giving the magnetic field an ontological priority in relation to the electric field or the electric charge, and as an experimental proof of what Hermann Weyl did not want to recognize: that the physical structure of space contains a right-hand screw; that there is a fundamental asymmetry that leads us precisely to another type of symmetry whose starting point is not a line, but an ontological center that contains in itself a fundamental polarity, i.e., the same magnetic field.
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You wrote:
"Complex numbers are only introduced because the area "under the curve" of a function is defined to be negative. Defining an area to be negative results in square roots of negative numbers being necessary to work with unknown values of x and y resulting in the "negative" area. Any physical representation using complex numbers can use other methods that are more physically specific for the representation by modifying the function that represents the system."
In electrical engineering, we use complex numbers, fundamentally because with them, the differential equations that result from Maxwell's equations, can be reduced to simple algebraic equations, which simplify the solution of those equations, and that is for the remarkable property of Euler's Equation, to remain the same, with those operations that represent change, I mean integration and differentiation, and in fact, sqr(-1) is just a symbol, for differention, as it were, two different order of reality such as active power and reactive power in IE, or time and space, in the case of QM, as is shown, with Schrödinger's wave equation based on complex numbers; here is in fact the great incompatibility, between QM and GR, because GR was coinceived by using a set of "real equations" in which time was a kind of variable of the same sort as space.
Einstein never thought of using complex numbers, and here lies in a certain sense of even the incompatibility between ER and GR...the one for linear systems, and the second for rotational systems.
When we treat both ER and GR with complex numbers, there is no incompatibility anymore as I have shown in various paper, including that one The Principle of Synergy and Isomorphic Units. Or in my unplished book in spanish, Física, Semiótica y Ontología.
Anyway this is the point of view of an IE, that had the opportunity, to text the use of complex numbers, for solving the state of a system of interconnected nodes of that network that constitute the most complex system built by man, I mean the Power System, from which we all depends daily. Solving with a real time state Estimator, a complex system of multiple interconected nodes, certainly is the best proof that complex numbers are for real... there is a real need, in my humble opinion of real paradigm shift regarding the unfortunate use of complex numbers, for considering sqr(-1), an imaginary unit as was named by Descartes... it is a symbol for separating two different orders of reality, that cannot be reduced the one to the other just as time and space.
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I am working in Barium ruthenate triple perovskites. I have been observing proper downward peaks at about 30 K, with the minima shifting to higher temperature for higher frequencies. The magnitude of the dips is also higher for higher frequencies. An exactly opposite trend is seen in the imaginary part of ac susceptibility data at the same temperature. There is no transition visible at 30 K in the DC magnetization or heat capacity data. The measurement was carried out in the Quantum Design SVSM MPMS3 multiple times and from multiple instruments at a magnetic field of 3 oe. I have observed this in two different Barium ruthenate triple perovskite compounds of mine. I had also carried out the ac susceptiility measurement in ACMS option of QD PPMS with 13 Oe magnetic field and this anomaly at 30 K is absent. Figures are given for reference.
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We have observed that the AC phase angle vs Temperature also peaks around 30 K. Can this be a artifact in that case? If so why it is happening in triple perovskite barium ruthenates in the SVSM measurement? Can we subtract this effect and get the original data? If so how? Figure given for refrence.
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When there is no magnetic field in the simulation, emittances given by the postprocessing and my own code are same. But when there is magnetc field in the simulation, no matter how small of the field, emittances parallel to magnetic induction are different.
The simulation software is CST Studio Suite 2020 Particle Tracking Solver. For the same structure of RF negative hydrogen ion source, the H- beam is extracted from plasma electrode and accelerated by the extracted electrode and accelerated electrode. There are two pairs of rod filter magnet in this structure.
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Christian Baumgarten I understand what you're saying is that the presence of a magnetic field can cause an increase in the emittance, and that is normal.
Finally, I found the issue. It was caused by an error in the emittance calculation method in CST. Nonetheless, I appreciate your help, and I will contact the technical support team at CST to further investigate and confirm the cause of the problem. Thank you.
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It is commonly believed that the concept of electron spin was first introduced by A.H. Compton (1920) when he studied magnetism. "May I then conclude that the electron itself, spinning like a tiny gyroscope, is probably the ultimate magnetic particle?"[1][2]; Uhlenbeck and Goudsmit (1926) thought so too [4], but did not know it at the time of their first paper (1925) [3]. However, Thomas (1927) considered Abraham (1903) as the first to propose the concept of spinning electron [5]. Compton did not mention Abraham in his paper "The magnetic electron" [2], probably because Abraham did not talk about the relationship between spin and magnetism [0]. In fact, it is Abraham's spin calculations that Uhlenbeck cites in his paper [4].
Gerlach, W. and O. Stern (1921-1922) did the famous experiment* on the existence of spin magnetic moments of electrons (even though this was not realized at the time [6]) and published several articles on it [7].
Pauli (1925) proposed the existence of a possible " two-valuedness " property of the electron [8], implying the spin property; Kronig (1925) proposed the concept of the spin of the electron to explain the magnetic moment before Uhlenbeck, G. E. and S. Goudsmit, which was strongly rejected by Pauli [9]. Uhlenbeck, G. E. and S. Goudsmit (1925) formally proposed the concept of spin[3], and after the English version was published[4], Kronig (1926), under the same title and in the same journals, questioned whether the speed of rotation of an electron with internal structure is superluminal**[10]. Later came the Thomas paper giving a beautiful explanation of the factor of 2 for spin-orbit coupling[11]. Since then, physics has considered spin as an intrinsic property that can be used to explain the anomalous Seeman effect.
The current state of physics is in many ways the situation: "When we do something in physics, after a while, there is a tendency to forget the overall meaning of what we are working on. The long range perspective fades into the background, and we may become blind to important a priori questions."[11]. With this in mind, C. N. Yang briefly reviewed how spin became a part of physics. For spin, he summarized several important issues: The concept of spin is both an intriguing and extremely difficult one. Fundamentally it is related to three aspects of physics. The first is the classical concept of rotation; the second is the quantization of angular momentum; the third is special relativity. All of these played essential roles in the early understanding of the concept of spin, but that was not so clearly appreciated at the time [11].
Speaking about the understanding of spin, Thomas said [5]: "I think we must look towards the general relativity theory for an adequate solution of the problem of the "structure of the electron" ; if indeed this phrase has any meaning at all and if it can be possible to do more than to say how an electron behaves in an external field. Yang said too: "And most important, we do not yet have a general relativistic theory of the spinning electron. I for one suspect that the spin and general relativity are deeply entangled in a subtle way that we do not now understand [11]. I believe that all unified theories must take this into account.
What exactly is spin, F. J. Belinfante argued that it is a circular energy flow [12][15] and that spin is related to the structure of the internal wave field of the electron. A comparison between calculations of angular momentum in the Dirac and electromagnetic fields shows that the spin of the electron is entirely analogous to the angular momentum carried by a classical circularly polarized wave [13]. The electron is a photon with toroidal topology [16]. At the earliest, A. Lorentz also used to think so based on experimental analysis. etc.
Our questions are:
1) Is the spin of an electron really spin? If spin has classical meaning, what should be rotating and obeying the Special Relativity?
2) What should be the structure of the electron that can cause spin quantization and can be not proportional to charge and mass?
3) If spin must be associated with General Relativity, must we consider the relationship between the energy flow of the spin and the gravitational field energy?
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* It is an unexpectedly interesting story about how their experimental results were found. See the literature [17].
** Such a situation occurs many times in the history of physics, where the questioned and doubted papers are published in the same journal under the same title. For example, the debate between Einstein and Bohr, the EPR papers [18] and [19], the debate between Wilson and Saha on magnetic monopoles [20] and [21], etc.
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Reference:
[0] Abraham, M. (1902). "Principles of the Dynamics of the Electron (Translated by D. H. Delphenich)." Physikalische Zeitschrift 4(1b): 57-62.
[1] Compton, A. H. and O. Rognley (1920). "Is the Atom the Ultimate Magnetic Particle?" Physical Review 16(5): 464-476.
[2] Compton, A. H. (1921). "The magnetic electron." Journal of the Franklin Institute 192(2): 145-155.
[3] Uhlenbeck, G. E., and Samuel Goudsmit. (1925). "Ersetzung der Hypothese vom unmechanischen Zwang durch eine Forderung bezüglich des inneren Verhaltens jedes einzelnen Elektrons." Die Naturwissenschaften 13.47 (1925): 953-954.
[4] Uhlenbeck, G. E. and S. Goudsmit (1926). "Spinning Electrons and the Structure of Spectra." Nature 117(2938): 264-265.
[5] Thomas, L. H. (1927). "The kinematics of an electron with an axis." The London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science 3(13): 1-22.
[6] Schmidt-Böcking, H., L. Schmidt, H. J. Lüdde, W. Trageser, A. Templeton and T. Sauer (2016). "The Stern-Gerlach experiment revisited." The European Physical Journal H 41(4): 327-364.
[7] Gerlach, W. and O. Stern. (1922). "Der experimentelle Nachweis der Richtungsquantelung im Magnetfeld. " Zeitschrift f¨ur Physik 9: 349-352.
[8] Pauli, W. (1925). "Über den Einfluß der Geschwindigkeitsabhängigkeit der Elektronenmasse auf den Zeemaneffekt." Zeitschrift für Physik 31(1): 373-385.
[9] Stöhr, J. and H. C. Siegmann (2006). "Magnetism"(磁学), 高等教育出版社.
[10] Kronig, R. D. L. (1926). "Spinning Electrons and the Structure of Spectra." Nature 117(2946): 550-550.
[11] Yang, C. N. (1983). "The spin". AIP Conference Proceedings, American Institute of Physics.
[12] Belinfante, F. J. (1940). "On the current and the density of the electric charge, the energy, the linear momentum and the angular momentum of arbitrary fields." Physica 7(5): 449-474.
[13] Ohanian, H. C. (1986). "What is spin?" American Journal of Physics 54(6): 500-505. 电子的自旋与内部波场结构有关。
[14] Parson, A. L. (1915). Smithsonian Misc. Collections.
[15] Pavšič, M., E. Recami, W. A. Rodrigues, G. D. Maccarrone, F. Raciti and G. Salesi (1993). "Spin and electron structure." Physics Letters B 318(3): 481-488.
[16] Williamson, J. and M. Van der Mark (1997). Is the electron a photon with toroidal topology. Annales de la Fondation Louis de Broglie, Fondation Louis de Broglie.
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[17] Friedrich, B. and D. Herschbach (2003). "Stern and Gerlach: How a bad cigar helped reorient atomic physics." Physics Today 56(12): 53-59.
[18] Bohr, N. (1935). "Can quantum-mechanical description of physical reality be considered complete?" Physical review 48(8): 696.
[19] Einstein, A., B. Podolsky and N. Rosen (1935). "Can quantum-mechanical description of physical reality be considered complete?" Physical review 47(10): 777.
[20] Wilson, H. (1949). "Note on Dirac's theory of magnetic poles." Physical Review 75(2): 309.
[21] Saha, M. (1949). "Note on Dirac's theory of magnetic poles." Physical Review 75(12): 1968.
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You are most welcome, Prof. Chian Fan
In Theoretical Solid State Physics are the so called noncentrosymmetric crystals, for them spin is not anymore a good quantum number, and a new term is introduce: Helicity.
Therefore your question is relevant.
Kind Regards.
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What is the (maximum) magnetic field outside a superconductive disk located in a uniform magnetic field B and very close to the edges? (Consider the London penetration depth to be zero and let the magnetic field be perpendicular to the disk if it was a perfect conductor.) According to the article attached below, the maximum field can be four times the external field (4B), though I am not sure.
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It would be better to look at LANDAU, L. The Intermediate State of Supraconductors. Nature 141, 688 (1938). https://doi.org/10.1038/141688a0.
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Thanks alot
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@Kamran Ahmad
Please, if you have any files in this field, send it to me.
Thanks alot
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Hey there, I am using CST Microwave Studios for Power Source (Magnetron) analysis. I need help in Particle in Cell simulations to analyze the E field (V/m) value at specified distances (0.5-2 Kms) from the power source. But i am unable to set the parameters correctly i.e Mesh Settings, Far field Probes and field monitors. Also need help with excitation of cathode and the ports and magnetic field settings.
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Khawar Shafiq Did you find the answer for your question? Can you please post it if you found the answer earlier. I have the same question. I want to plot electric field as a function distance too.
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During the VSM measurement, the data I measured shows hysteresis curve appearing only on the positive side of magnetic field what could be the possible reasons for that ?
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Yes, I completely agree with Marek Gutowski. The effect of the exchange bias of hysteresis loops - aka the Meiklejohn-Bean effect, was discovered in 1956 in the article to which I gave a quote. The effect continues to be actively studied to this day. Hundreds of articles are published every year. In particular, the effect of exchange bias training is also being studied in a variety of materials that are inhomogeneous in terms of magnetic ordering. It can manifest itself not only in magnetic but also in electronic transport properties as well, as magnetoresistance hysteresis loops may also be biassed by the same magnetic interaction.
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Fermions have four properties: charge, spin moment, mass and gravitational field.
1) Why don't we consider the spin moment as an effect of "magnetic charge", so that we don't need to look for magnetic monopoles [1][2][3].
2) If this is correct, we can divide the four properties into two pairs, charge e, magnetic charge g [4]; mass m and gravitational field G.
3) We will find that e and g are inseparable (except, it seems, for neutrinos) and m and G are definitively inseparable. e satisfies Gauss's theorem for the electric field and g can likewise satisfy Gauss's law for the magnetic field, as long as it appears in bipolar form.
4) So, why four properties instead of one or more? In what way and in what relationship would these four properties be set in one?
[1] Dirac, P. A. M. (1931). "Quantised singularities in the electromagnetic field." Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character 133(821): 60-72.
[2] Acharya, B., J. Alexandre, P. Benes, K. S. Babu and etl. (2021). "First Search for Dyons with the Full MoEDAL Trapping Detector in 13 TeV p p Collisions." Physical Review Letters 126(7): 071801.
[3] Preskill, J. (1984). "Magnetic monopoles." Annual Review of Nuclear and Particle Science 34(1): 461-530.
[4] Dirac, P. A. M. (1948). "The theory of magnetic poles." Physical Review 74(7): 817.
Keywords: Fermion, Charge, Monopole, magnetic charge, Spin moment, Gauss's law, Maxwell equation, MoEDAL, Standard Model.
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Dear Stam Nicolis,
fermions like electrons have no need to obey "internal symmetry groups" as you write. On the contrary, we derive these symmetry groups from observations on particles. Yesterday we knew nothing about these groups, tomorrow we will come up with something else. But in any case, we will have to answer the school questions about why there is a circular magnetic flux around a conductor with direct electric current and why physical bodies with mass cause gravitational attraction to each other.
Sometimes it can be harmful to read many textbooks.
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I wanna to asked that if I have a cylindrical permanent magnet and I can measure the Three-dimensional magnetic vector(Bx,By,Bz) of every point, how can I calculate the space position(x,y,z) from the magnetic field(Bx,By,Bz)? Thank you!
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Dear friend Ruohai Hu
To determine the spatial position of a point in a magnetic field, you can use magnetic field sensors, such as Hall effect sensors or magneto resistive sensors, to measure the magnetic field strength (Bx, By, Bz) at different points. Once you have obtained the magnetic field strength at a particular point, you can use mathematical equations to calculate the position of the point.
The calculation involves the use of the magnetic dipole moment of the permanent magnet, which is a vector that represents the strength and direction of the magnetic field generated by the magnet. Using the magnetic dipole moment and the measured magnetic field strength at a particular point, you can calculate the distance and direction from the magnet to the point.
There are various mathematical models and algorithms that can be used to calculate the position from the magnetic field strength measurements, such as the dipole inversion method or the iterative method. These methods typically involve solving a set of equations that relate the magnetic field strength to the position and orientation of the magnet.
It is important to note that the accuracy of the position calculation depends on several factors, such as the accuracy of the magnetic field measurements, the geometry of the magnet, and the complexity of the magnetic field distribution. Therefore, careful calibration and validation of the measurement system and the mathematical model are necessary to ensure accurate and reliable results.
Overall, measuring the magnetic field strength at different points and using mathematical models to calculate the spatial position can provide a non-invasive and convenient method for characterizing the magnetic field distribution of a permanent magnet.
Here are some references that might be helpful for further reading:
1. C. C. Thong and J. A. Deans, "On the determination of magnetic field and position using a magnetometer array," Measurement Science and Technology, vol. 12, no. 10, pp. 1601-1609, 2001.
2. D. D. Dibenedetto, "Magnetic field mapping and localization of ferromagnetic objects by means of spatial derivatives," Journal of Applied Physics, vol. 75, no. 10, pp. 5790-5792, 1994.
3. J. J. Han, D. K. Kim, K. H. Kwon, and K. S. Lee, "Three-dimensional position measurement of a magnet by using a single fluxgate sensor," Journal of Magnetism and Magnetic Materials, vol. 321, no. 6, pp. 736-741, 2009.
4. C. Liu, Q. Liao, S. Zhou, and L. Xu, "Position detection of magnet based on magnetic field distribution," Review of Scientific Instruments, vol. 89, no. 1, p. 015103, 2018.
5. M. Schubert, T. B. Tang, and W. Wiesbeck, "Magnetic field-based position determination with high spatial resolution," IEEE Transactions on Magnetics, vol. 35, no. 5, pp. 4009-4015, 1999.
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Hello,
My name is Radu Jubleanu, I am PhD student at the Politehnica University of Bucharest. I work in the field of magnetic storage in superconductors, I studied some works related with superconductors , and I have a confusion related to the magnetic anisotropy of them.
More precisely, I would like a clarification, related to parallel and perpendicular magnetic fields. I saw that there are Jc curves as a function of B. But it is not clear to me who is B. Who produces this external magnetic field?
Thank you!
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The magnetic field is varied using solenoid or Helmholtz coils. The external magnetic field is produced by the instrument used for measurement (SQUID, VSM)
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I have received as a comment expressing recent research that: Of course this is 100% correct because energy is the universal electric field and every quantum of energy generates a corresponding vector within the magnetic field (and visa versa). Moreover, vectors act instantaneous because vectors are 1 dimensional (vectors are not bound to the speed of light).
One may have a long re-bar (roughened metal bar used to reinforce concrete) and would find that a hammer tap on the end results in a propagating wave that eventually reaches the other end. A strong blow with a sledge hammer would produce that result plus a longitudinal motion of the entire bar that would affect anything in contact with the far end much sooner, almost instantaneously because the bar would move as a whole.
Are electric field vectors stiff in the latter sense of the re-bar's motion as is implied by "instantaneous" in the above comment?
Cited research as well as opinion might get an old guy up to speed on this since he'll never get it all read. Note, this is not about an EM wave propagating in accord with theories treating that phenomenon. The speed of light must not be allowed to confuse this new awareness of recent research. lfh 3-13-23
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The short answer is No, they aren’t.
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In Hall effect, when a magnetic field is applied to a sample, electrons are deflected and accumlate sideways. Can one determine this angle? I have a formula and want to check it.
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The angle I found is given by tan(theta)=Bm/(mu_0n e hbar), m electron mass and h is the Planck constant divided by 2 pi.
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Please elaborate your explanations..
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As charges move forward, a Lorenz force pulls in , the final motion is a spiral,
circular plus translational. In Tokomaks you want to prevent charges touching the borders.
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Kindly share the link of any video tutorial or data.
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Dear Prof. Muhammad Asif
Kindly go through the lecture of the wiki on FDTD, at the end of the wiki, it will be a list of different simulations tools, you can choose from there any you want.
Kind Regards.
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Some people believe that it is the end of physics laws. this question has taken around a century to be solved. But what are the problems? please inform them.
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Electrmagnetic fields are sources of gravitational fields, a perfectly well understood consequence of Einstein’s equations. It’s just that there’s nothing particular about the electrooagnetic field as such, since it’s just the energy and momentum of the field that matter. It would be a good idea to study general relativity from a textbook, rather than from books for the general public. And not yo worry too much about any supposed ``end of physics laws", which doesn’t mean anything.
Quantum electrodynamics has been understood since the end of the 1940s-this hasn’t led to the end of interest in condensed matter physics, just the opposite; as in the discovery of new phenomena in this field.
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Hi everyone,
I'm using COMSOL Multiphysics Magnetic field interface to modeling 3 phase power reactor. According to COMSOL Manual reference the best preconditioner for iterative solver in magnetic field is geometric multigrid (GMG) where in coarse solver configured with Auxiliary-Space Maxwell (AMS). Whereas, AMS is not support complex number and each phase has 120 degrees phase difference with each other (for ex. current in phase B= Irms*exp(j*2*pi/3)). Also, I have tried direct solver instead of AMS and solution not converged. Does any one know how to configure the GMG preconditioner or any solution for get true results?
Thanks
Best regards,
AhmadReza
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Hello, in your model there's some hidden domain between the coils?
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I'm confused! In 13CNMR spectroscopy, is 13C nucleus used in the device? What exactly is the nature of the magnetic field produced by the device? From carbon 12 or 13? And does it only stimulate the 13C in the sample or does it also stimulate the 12C in our sample? (Of course, the abundance of 13C is much less than 12C)
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Stern-Gerlach experiment is often seen as idealization of measurement. Using strong magnetic field, it makes magnetic dipoles (of e.g. atoms) align in parallel or anti-parallel way. Additionally, gradient of magnetic field bends trajectories depending on this choice.
Magnetic dipoles in magnetic field undergo e.g. Larmor precession ( https://en.wikipedia.org/wiki/Larmor_precession ) due to τ=μ×B torque, unless μ×B=0 what means parallel or anti-parallel alignment.
Precession means magnetic dipole becomes kind of antenna, should radiate this additional kinetic energy. Thanks to duality between electric and magnetic field ( https://en.wikipedia.org/wiki/Duality_(electricity_and_magnetism) ), we can use the attached formula for precessing electric dipole, e.g. from http://www.phys.boun.edu.tr/%7Esevgena/p202/docs/Electric%20dipole%20radiation.pdf .
Using which I get power like 10^−3W, suggesting radiation of atomic scale energies (∼10^−18J) in e.g. femtoseconds (to μ×B=0 parallel or anti-parallel).
So can we see spin alignment in Stern-Gerlach as a result of EM radiation of precessing magnetic dipole?
Beside photons, can we interpret other spin measurement experiments this way?
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I was suggested very nice article: "Phenomenological theory of the Stern-Gerlach experimen" by Sergey A. Rashkovskiy with very detailed calculations - getting ∼10−10s times for such alignment of atoms in Stern-Gerlach: https://www.preprints.org/manuscript/202210.0478/v1
Calculations are straightforward from equation (3) there for magnetic dipole in external magnetic field.
My very approximated evaluation from radiation of abundant energy suggested a few orders of magnitude fasted alignment - bringing very interesting question if they are equivalent, how does energy balance looks above (?)
Anyway, this is another confirmation that classical magnetic dipoles in external magnetic field have tendency to align in parallel or anti-parallel way.
This "classical measurement" is deterministic and time-reversible: if recreating reversed EM, in theory one could reverse the process ...
What is nonintuive here is that such EM radiation carrying energy difference here seems different than in "optical photon", might be delocalized (?).
The big question is the minimal size to be able to apply this "classical measurement" - minimal size of such magnet: a million atoms? Thousand atoms? Single atoms? Electron?
Experimentally in Stern-Gerlach they observe the same conclusion, such alignment is also well known for electrons (e.g. https://en.wikipedia.org/wiki/Sokolov%E2%80%93Ternov_effect ), for which they observe both Larmor precession, but also much more complex acrobatics in EM field: spin echo ( https://en.wikipedia.org/wiki/Electron_paramagnetic_resonance#Pulsed_electron_paramagnetic_resonance )
So where is the classcial-quantum boundary here?
I don't see it, nor need for "unitary evolution - hocus pocus/measurement/abracadabra - unitary evolution" ...
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Hi,
I want to simulate a solenoid magnetic field in Comsol. Where should I start?
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Crisis and emergency alert http://youtu.be/Ng1-KJueYiU Time for the people to stand together to bypass, help us build the bypass. We have the foundation's know
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Apropos the Meissner Effect : how is a totally still magnetic field expelled from the interior of a superconducting body, when it is cooled below the transition temperature? From whence do the supercurrent elements obtain their impulse ; how can they suddenly become screening currents, without a cause?
Conversely, it is quite understandable that bringing a superconducting body into a magnetic field-- in this case the supercurrent elements obtain their impulse from a changing magnetic field, via the Lenz-Faraday Law. But in the above case, the magnetic field is absolutely still, and so cannot possibly provide the mechanism to set up surface screening currents.
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An other explanation. Cooper pairs randomly drift through the crystal with a non-zero kinetic energy. When the motion of Cooper pairs is non-dissipative, then the disordered drifts can align via the Lorentz force to minimize the magnetic energy in the interior. So the magnetic energy is expelled from the bulk without changing the kinetic energy of electron pairs and the total free energy of the crystal decreases.
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I was just wondering if hall effect sensor would measure magnetic field inside a pipeline when being placed inside. As I am currently doing a project to identify corrosion in a pipeline, i was hoping to use it to find the magnetic fields to detect corrosion in the pipe.
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I guess you going to rely on Erath magnetic field and since it is rather waek you need to use more sensitive Fluxgate type sensor. There seem to be a lot for publications on such topic e.g.
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Hi everyone
Considering a magnetized plasma with non-isothermal electrons ( free and trapped electrons ) what is the influence of the magnetic field on the electron capture (trapping)?
and what processes are used to determine the proportion of captured electrons?
Thanks
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Thank you all for your answers,
but the electrons are non-isothermal, i.e., represented by a vortex-like distribution function. In other words, there are free and trapped electrons, and the last ones are trapped in the electrostatic potential trough.
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I am trying to build a setup to cure magnetic powders in a polymer matrix in a uniform magnetic field to align the particles in certain orientations. What would be the a setup to do this? In literature I do see some researchers use electromagnets and some use electromagnets. What would be the proffered method in terms of having control over the field being applied?
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James E Hanson Hi Professor, I have tried using permanent magnets the issue is with PM is that the field intensity is non uniform and it tends to pull the powders out of the matrix. I find that most people in literature for magnetorheological elastomers tend to use electromagnets but I am unsure how they are able to cure their polymer matrix as the uniform fields even in electromagnets is within a very small region and it doesn't seem like it could accommodate anything to apply heat for curing to occur. Furthermore they test these smart composites using DMA or rheometers again for which they would need to apply magnetic field over a considerable area to measure change in the young's modulus of the smart composite. I have read about a PEM-1022LS magnetic system in some of the literature but could not find any info on what this system is online any chance you have heard of this?
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