Science topic

# Magnetic Field - Science topic

Explore the latest questions and answers in Magnetic Field, and find Magnetic Field experts.
Questions related to Magnetic Field
Question
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!
The magnetic field is varied using solenoid or Helmholtz coils. The external magnetic field is produced by the instrument used for measurement (SQUID, VSM)
Question
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
The short answer is No, they aren’t.
Question
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.
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.
Question
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.
The field is 1B because the disc is in intermedial condition.
Question
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.
Question
Kindly share the link of any video tutorial or data.
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.
Question
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.
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.
Question
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,
Hello, in your model there's some hidden domain between the coils?
Question
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)
Question
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?
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" ...
Question
Hi,
I want to simulate a solenoid magnetic field in Comsol. Where should I start?
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
Question
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.
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.
Question
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.
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.
Question
In doped multiferroic composites of BTO-CFO, i observed increase in dielectric constant by the application of magnetic field. However, in some cases, a decrease in dielectric constant was observed by applying magnetic field. Which factors may be responsible for such behavior?
I am replying to this question as my working research field in same,
In the case of magnetodielectric(MD) it is true that some composite shows increased MD i.e. positive MD effect some shows negative magnetodielectric effect. The MD effect depends on a numbers of factors such as type interphase coupling between the phases in the composite materials, microstructures of the two phases, inter-diffusion effect at the interfaces, conductivity differences of the two phases, change of conductivity with magnetic field, presents of defects porosity, magnitudes of local fields etc.
Depending on the above mentioned parameters , the dielectric response or the permittivity of the composite material should have to be analyzed by applying a magnetic fields.
So, depending upon the nature of permittivity change occurring in the composite material negative or positive MD effect can be predicted.
Question
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
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.
Question
Hello fellow human beings;
I am currently trying to find a way to simulate multiple frequencies entering one conductor and watch the evolution of the magnetic field of this particular conductor. One of the idea could be to write an equation which describes the behaviour of the two signals and to inject that signal (described by the equation) through the conductor.
I currently have CST studio the student's version, have access to Altair FLUX and i have femm.
I am open to test any software, as long as it gets the job done.
CST + wire antenna + orthogonality (different frequencies dont interact) + (at the end of all simulations done) linear superposition of the resulting fields, tell me what is the problem with this since it should simply work as CST numerically solves the EM problem (and simple conductors).
Question
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?
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?
Question
Temperature in umbra region is less compared to penumbra is it because of magnetic field or something else
Dear Jothsana: both previous answers are correct. But take into account that there is a magnetohydrodinamic effect for that: magnetic fields are associated with a "magnetic pressure" that complements "thermodynamical pressure" in the solar plasma up to the value of the environment pressure of equilibrium. So, where there is a magnetic field the thermodinamical pressure is lower, and the temperature diminishes (ideal gases law); as a result of the lower temperature the emission of blackbody radiation also diminishes.
Question
Why a low magnetic field of 100 Oe or 500 Oe is generally used to measure the Magnetization vs. Temperature curves for magnetic samples?
Question
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.
Hi, I just came across your post when doing trouble shooting on my NGS Minion cleanup (using HMW DNA of E. coli for WGS). Let's try if this chat would still be active...
For the clumping, I experienced the same and had a yield of approx. 3-5 ng/ul. Wy too low. So I resuspended the beads in another fraction of nuclease free water, vortexed the sample until resuspended, and then incubated for 5 min at 37 °C. This increased the yield from 3-5 ng/ul to 60-80 ng/ul. The effect of vortexing on DNA fragmentation is of course detrimental, I am still waiting on the sequencing run to see how my N50 will be affected.
Regarding a later cleanup step during barcoding of samples, I usually have a recovery of 50-75% with the Ampure XP beads. Is this within your usually range?
Thanks and best regards.
Question
Sudden reversal in magnetic field is the origin of switchback. The reconnecting field lines creates shear driven turbulence.
u r welcome~
Question
The high charged currents at the deep of earth exist because of the friction (sliding) between the different layers of earth caused by the planet spin and rotation. This creates moving layers of charges that persist and could be emplified in strength by nuclear phenomena.
The deeper we go in earth the higher is temperature ,thus, the higher is conductivity. So the upper sliding layer will be charged negative and the other positive. furthermore, The negative charged layer is faster in rotation than the positive charged one since the radius of its rotation is bigger.
That means that the we have two opposite magnetic fields but the strongest magnetic field is the one made by the upper layer (Faster charges , Closer to the crust).
The result of all the layers magnetic fields light be The earth magnetic field.
What do you think of this theory that refuses an effective center of magnetism like the example of the center of mass G that doesn't hold all the effective mass?
Earth's iron core.The rotation of the earth with its iron core creates a magnetic field around it like the rotor of an electric motor
Question
I used a Co-planar waveguide (CPW) as a microwave source to measure the ferromagnetic resonance (FMR) of thin films. While taking the measurement, I kept the frequency constant and swept the magnetic field to find the resonance field. And I did the same procedure for different frequencies.
During the measurement, I observed the FMR signal amplitude decreased with the frequency increase. What may be the possible reason behind the decrease in amplitude?
I am attaching the representative image of the FMR signals for different frequencies.
if the film contains rare-earth ions with a strong spin-orbit interaction, then, according to the theory of slow relaxation, the FMR damping increases with increasing frequency
Question
• I have tried increasing the magnetic field still no point if saturation.
It can detect upto 50 emu, but as the sample is too small it's difficult to get the readings. For little bigger samples I am getting perfect curve.
Question
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?
I think you can add volume force for magnetic fluid. The volumetric force can be expressed in terms of the magnetic field force on the magnetic fluid.
Question
When shear is strong enough,switchback and isotropication occurs . In data obtained from PSp encounter-8 ,many many reversal in radial component of magnetic field
A switchback is defined not only in terms of the radial component of the magnetic field, B_R. The Sun has magnetic sectors, with magnetic field "away" from or "toward" the Sun, and such magnetic field orientation is carried out with the solar wind. From one of Maxwell's equations, a sudden change in magnetic field B implies a current sheet at the boundary. This is called the heliospheric current sheet (HCS). But a change in B_R due to a changing sector, or an HCS crossing, is *not* termed a switchback. In Parker Solar Probe's 8th encounter, there were several HCS crossings but actually very few switchbacks.
So how can you tell whether B_R is reversing as an HCS crossing or a switchback? Ideally you would use another type of data. Heat flux electrons, a.k.a. suprathermal or strahl electrons in the solar wind, are found to stream away from the Sun along the local B line. So if you see the pitch angle distribution of such electrons *not* changing, which B_R reverses, that is a switchback. Before/after an HCS crossing, the dominant pitch angle would reverse. Similarly, the cross-helicity of magnetic and velocity fluctuations is generally characteristic of outward-moving Alfven modes, so that behaves like the strahl electron pitch angle: it reverses before/after an HCS crossing but not during a switchback. Or a very simple but not physically rigorous way to identify a switchback is as a very temporary reversal of B_R, with the same sign before and after the switchback.
Finally, given that electron strahl and cross helicity are not reversing, many people define a switchback as B_R changing sign. However, a more general definition is rotation of the B vector beyond some angle, with the threshold angle as a variable parameter (see Dudok de Wit et al. 2020).
Question
Dear all
How can be activated the angle of magnetic field (γ) in FLUENT for convection heat transfer, as shown in Figure 1? step by step please.
Following...
Question
In most of the textbooks on NMR, we come across the fact that under the 1.4 Tesla external magnetic field, the precession frequency of 1H (proton) is 60 MHz. Can anyone tell why it's always mentioned as 1.4 T instead of 1 T?
Ganguly
1.4 Tesla is the maximum field strength achievable in a conventional configuration (natural magnet-at the time) which was known in the early stage of NMR development (before the manufacture of superconducting magnets).
Good luck
Question
We have measured the magnetic field dependence of the ordered magnetic moment of Tb and Mn in multiferroic TbMn2O5 by single crystal neutron diffraction. The Mn moment does not change significantly with magnetic field but Tb moment does. How can I calculate the expected field variation of Tb moment from crystal field effects?
Question
On the magnetic field and its quantum nature ..
Electromagnetic waves travel at the speed of light. Let's think, how can an electric and magnetic attribute travel at the speed of light. The electric and magnetic nature will have to accelerate each other. If the electrical and magnetic nature of the universe is accelerating and reaching the speed of light, what is the main reason for this? Electric current can create a magnetic field. The electrical difference in the universe will cause the magnetic field to differ. But what does this change in the universe indicate? If the electrical nature of a substance changes, its magnetic nature will also change. The electrical quality is directly proportional to the magnetic quality. From here, we also reveal that the electrical change affects the magnetic nature of the material. If the magnetic nature changes, we can say that the natural attraction of that substance to another substance changes. If the electric wave increases, since the magnetic field will increase in a substance, the gravitational attraction of that object to another object will increase. In other words, Dear SIR ISAAC NEWTON (20 MARCH ANNIVERSARY, WITH REGARDS FROM THE WHOLE WORLD OF SCIENCE!) INCREASED GRAVITY OF MATTER MEANS INCREASED MASS OF MATTER IN SPACE TIME. SO MAGNETISM MAKES AN OBJECT TO ITS MASS. CAN I ACTUALLY ASK WATER QUESTIONS? CAN I ACHIEVE THE SPEED OF LIGHT BY MAKING A MAGNETIC VEHICLE? IF WE GO TO THE ESSENTIAL SUBJECT, IF MAGNETISM MAKES AN OBJECT OVER MASS, IT INCREASES GRAVITY. OUR UNIVERSE MAY BE EXPANDING FOR MAGNETISMIC REASONS. SO HOW DO WE EVALUATE MAGNETISM AND ELECTRICITY ACCORDING TO QUANTUM THEORY? Quantum theory means that a particle can be in more than one place at the same time. and atoms (submatter) are conscious. If magnetism increases the mass of a substance above matter, that is, if gravity increases, what happens under matter? and what do we say about quantum theory? Could quantum theory be another form of magnetic property? Because when the magnetic quality increases, we understand that the effect of two objects is in two different places. So let's think about it this way: When quantum theory qualifies as the opposite pole in magnetism and - and the same pole -- it can be as follows: Quantum theory is formed by using the magnetic property. This is how it happens. It is a system that takes two opposite poles and two same poles under its influence at the same time and realizes this. In quantum theory, opposite and same poles of magnetism function at the same time.
Yes, magnetism in substances has a quantum nature. This is not so difficult to see in solid-state physics, for a paramagnetic quantum gas where for each atom the magnetic moment m is:
m = e/(2mc) (L + 2 S) with the angular momentum L (that in quantum theory is also quantized) and the spin part S.
Therefore from macroscopic measurements, one can obtain information about the magnetic properties of substances, including the quantum state of the atoms. This is based on the quantum nature of magnetic phenomena, as you pointed out.
The induced effect from the magnetic field occurs in quantum theory due to the uncertainty principle, since it is impossible to say exactly at what point r in space a particle with momentum p is located, therefore the expression for the induced magnetic moment mind for a system of particles is
mind = - e2/(2mc2) Σi ri × A
Best Regards
Question
Apparently, oscillating magnetic field has positive effects on the flow characteristics.
If we apply an oscillating magnetic field on a ferrofluid flow, will a secondary magnetic filed be produced by the flow against the primary one or not (just like the electromagnetic induction)?
It is important, since we should know how much power is needed to increase the flow properties.
Thank you.
You are most welcome, Prof. Hossein Akhlaghi Garmejani
I noticed that the topic is actually being studied in some of the Russian literature. But of course, the language is a problem. Try Google Translate & check a few searches with the works you consider more important.
I saw in the past several monographies dedicated to ferrofluids in the former USSR since the problem is tractable theoretically.
Best Regards.
Question
In CST studio, I'm computing magnetic fields for a specific cusp configuration and exporting an ASCII file with x,y,z, and Bx, By, and Bz coordinates. I'd want to make a vector field plot out of these numbers. Plotting it in CST is easier because it is done automatically. I'd like to plot it in MATLAB with some tweaks. What should I do? I tried using quiver plot, but it didn't turn out well. I've included a CST reference image for the vector field I'd want to plot.
Question
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.
@Sergey V.Kutsaev, thanks for your reply. I am actually looking to analyze the E Field strength with varying distance from the cathode (particle source). Also is there a convenient method on CST to measure the power output of the magnetron structure.. Please guide. If you have any examples / tutorials on CST, i would be grateful if you can share.
Question
An electron is usually described as being a “point particle”. Collision experiments are interpreted as indicating an electron must be smaller than about 10-18 m. However, this size is incompatible with an electron also having physical angular momentum of ħ/2. An electron would need a radius of about 2 x 10-13 m and be rotating at the speed of light to have ħ/2 physical angular momentum. This conundrum forces physicists to postulate there must be an “intrinsic” form of angular momentum that does not involve rotation. However, the Einstein-de Haas experiment proves that reversing an electron’s spin with a magnetic field imparts physical angular momentum to a ferromagnetic rod. Do you believe there really is an “intrinsic” form of angular momentum that can be converted to physical rotation of an iron rod when an electron’s spin is reversed?
The alternative explanation is that experiments that attempt to measure an electron’s size have been misinterpreted. For example, if an electron’s electric field is considered a fundamental part of the electron’s structure, then it is ridiculous to ignore the fact that an electron’s energy is distributed over a much larger volume than 10-18 m radius. In fact, an electron’s classical radius of 2.8 x 10-15 m is the size where 100% of an electron’s energy would be in its electric field. A sphere with radius of 10-18 m and charge e would have more than 2,000 times too much electric field energy. The solution I have proposed incorporates an electron model that is a rotating quantized wave with a mathematical radius of 3.86 x 10-13m. What is your solution to the electron’s spin problem?
Taking the idea of Dirac as inspiration yields the following visualization: https://www.motionmountain.net/research.html#qed
Question
We have seen in our paper, that for a 10 solar mass non-rotating BH, magnetic field strength can reach up to 10^(5 to 6) Gauss close to the horizon. Now, if we notice the observation of EHT, they report for a 10^9 solar mass BH, field strength reaches up to 1-30 Gauss near the horizon. So, is there any specific explanation for how the magnetic flux changes from stellar to supermassive BHs?
Samik Mitra Using polarised light measurements around the M87 black hole, the EHT team discovered that the magnetic field strength ranges between 1 and 30 gauss. This amounts to around 50 times the intensity of Earth's magnetic field as measured near the planet's poles, where it is greatest.
Magnetism is caused by the heated gas that surrounds the black hole. The magnetic field is strengthened when the charged gas particles spin. The researchers discovered, however, that not all of the magnetic field simply spins with the spiraling gas.
Question
We have magnetic field variation of pyroelectric-current data. A complete cycle of magnetic field variation (0T to 1.3T, 1.3 T to -1.3 T, and -1.3T to 0T ) of pyrocurrent is measured along with time. we need magnetic field variation of polarization.
ARTICLE
Received 18 May 2015 | Accepted 26 Nov 2015 | Published 18 Jan 2016
Magnetoelectric effect and phase transitions
in CuO in external magnetic fields
Zhaosheng Wang1
, Navid Qureshi2, Shadi Yasin1,3, Alexander Mukhin4, Eric Ressouche5, Sergei Zherlitsyn1,
Yurii Skourski1
, Julian Geshev6,7, Vsevolod Ivanov4, Marin Gospodinov8 & Vassil Skumryev7,9
Question
I want to design a 3 axis helmholtz coil with 10 micro Tesla max magnetic field with copper wire of gauge 24, how to determine number of turns?
Your main problem will not be to generate a 10 μT field (just search for "Helmholtz coil" in Wikipedia, solve the equation for n*I) but to deal with the geomagnetic field. Depending on location, its strength is in the range 25 to 65 μT.
Solution 1: Build a shielding box from mu-metal. Might be expensive.
Solution 2: Generate a field of up to 75 μT in such a way that the sum of all fields equals the required 10 μT.
Question
Human dynasty in its millennium era. We have identified fire from the friction of stones and now we are interacting with Nano robots. Once it was a dream to fly but today all the Premier league, La liga and Serie A players travel in airplane at least twice in a week due to the unprecedented growth of human science. BUT ONE THING IS STILL ELUDING IN THE GLITTERING PROFILE OF HUMAN DYNASTY.
Although we have the gravitation theory, Maxwell's theory of electromagnetism, Max Planck's Quantum mechanics, Einstein's relativity theory and in most recently the Stephen Hawking's Big bang concepts...… Why can't we still revert back and forth into our life?
Any possibilities in future?
if not..
Why? in terms of mathematics, physics and theology??
Given Albert Einstein's theory of relativity, cosmology regarding the development of the universe, quantum mechanics, future technologies for building interplanetary spacecraft, etc., time travel is theoretically possible. But in practice the building of a time machine by humans is impossible. Even if a man would achieve the required technological development in the next several hundred years, unfortunately he would not have enough time for it. First of all, a person must first solve other global problems, such as the necessary one is urgent, i.e. in the perspective of the next max. 2-3 decades of time, stopping or significantly slowing down the progressing global warming process, achieving zero-emission economy and avoiding a global climate catastrophe, which may occur at the end of the current 21st century. In order for man to be able to create new technologies of the future, to be able to build interplanetary manned spacecraft, etc., he must first save the planet's climate, biosphere and biodiversity from the risk of almost total degradation.
Best regards,
Dariusz
Question
Hello to all dear experts. The conversation is open to all opinions about specialized fields and applications of the magnetic field impacts in various industrial technologies.
​Best Regards,
Direct Contact: +8801759 731605 (WhatsApp no.)
Magnetohydrodynamics (MHD) helps enormously to understand our closest start, Dr. Md. Fayz-Al-Asad The Sun.
In addition, MHD is crucial for our existence on planet earth since it also relates to the behavior of the Earth's magnetic field.
Best Regards.
Question
I want to know that How can I measure the magnetic flux density in HFSS? I have a box in my model that I defined as a magnetic media, I want to measure the magnetic flux density that is generate because of this particle. I know I can get the magnetic field strength Mag_H_field , but I want to know the B (magnetic flux density)
There is a big difference between B and H. B can be in a different direction to H inside a permanent magnet, or any magnetic material which has hysteresis.
In SI units uo is nearly 4 pi e-7, and ur can be from 1 to thousands depending on the material.
I don't know HFSS but you may be able to post-process by multiplying H by the magnetic properties of each material and so get B, which HFSS may plot for you, or give you values you can use.
Question
This question is the first step of a project which is in the start-up phase and aimed at understanding the physical meaning of exotic dimensions whose existence is proven in the work Linear microbundles.
We refer to Question 10.2 in the work Linear microbundles.
I know this. My question is about what happens varying the shape of inhomogeneity.
Question
Hi,
In relation to the coupling of fluid flow (gasoline) with magnetic field (permanent magnet) in experimental articles it is mentioned that in the presence of magnetic field, fuel properties such as density, surface tension and viscosity will change. I simulated this problem numerically recruiting the finite element method but I don't see these changes. I appreciate your help in advance.
Hi Thomas Cuff , I have seen quite a number similar patents.
Just like peer-review, the patent system isn't perfect and sometimes something gets patented that shouldn't be. It can be enough to claim a new twist on an old idea (like a magnet around the fuel line and the air supply of the engine, as in your example) and sometimes, maybe, the good people at the patent office just had a bad day. This problem is not limited to implausible claims, sometime ago we were troubled by a competitor's patent even though all the claims in said patent were already described in much older scientific literature...
Patent applications should contain novelties (1) and be non-trivial (2). But generally, neither of these two criteria will lead to an obvious and sharp demarcation.
Question
I am currently doing a project where I am making a curved electromagnetic track so that a superconductor can flux pin along it, moving wherever each solenoid is activate(where ever the magnetic field is present). In order to do this, I want to figure out how to calculate the force at one point around the magnetic field and compare it to another to figure out the optimal spacing between each row of solenoids on that curved track.
Question
Can some one guide me to some basic literature about designing inductively coupled RF discharge (preferably cylindrical). How to decide the diameter, number of turns, frequency, power, gas pressure etc. Rule of thumbs would also work if exact literature is not available. Oh yes and in presence of high external magnetic field.
The books of Pascal Chabert and Lieberman are the primary references, of course, but in addition to that this might help :
Question
Graphene is a superconductive material and superconductivity does not have magnetic field and the consequently no electromagnetic field . The Photon and Electron generation process takes place in electromagnetic field then how the generation of electron and positron takes place ?? How and Why the hexagonal structure of vacuum like graphene ??
You are most welcome Prof. Vivek Kumar Sharma there is one point I did not mention, mostly because I never worked on it, that is fractional statistics in CM.
Bose-Einstein and Fermi Dirac Quantum Statistics govern the 3D microscopic world from subatomic particles to the behavior of matter at room temperature. For example, bosons and fermions exhibit different behaviors: bosons like to stay in the same ground state while fermions stay in different states.
But I forgot to tell you that there is a 3rd quantum statistic for other quasiparticles that have been hypothesized: Anyons (also qubits). They are Fractional Quantum Statistics of quasiparticles in 2D (Wilczek, 1982, *) that have characteristics not seen in bosons or fermions.
If I recall well, they are called anyons because particles may obey any statistics, adopting any quantum phase when exchanging position [*].
Thank you so much for the interesting discussion, I appreciate it. I will try to check what about then in hexagonal 2D structures.
[*] Introduction to Fractional Statistics in Two Dimensions. In: Anyons. Lecture Notes in Physics Monographs, vol 14. Springer, Berlin, Heidelberg. 1992.
Question
How is it possible to detect a multidomain and a single domain in nanomagnets without using external magnetic field?
Of course. Magnetic domains appear to minimize the total energy, which has several contributions: magnetocrystalline energy, magnetostatic energy, etc. When you remove the external magnetic field, only the Zeeman energy goes to zero. As an example, you can find two different multidomain states in this recent paper:
But single domain magnetic states can be observed without any applied magnetic field also. For instance, shape anisotropy can help to stabilize single domain states, you can find many examples in the literature with magnetic nanowires. A curious case is obtained with T-shaped structures, since each branch of the T behaves as a single domain:
Finally, when the dimensions of the nanostructure are smaller than the domain wall width, single domain states can also be obtained at remanence, although if the dimensions are too small they cannot be stabilized (supermaramagnetic state).
Question
I have measured the Hall Resistance of a doped single crystal and found Anomalous Hall Effect. The pristine single crystal has also been reported to show Anomalous Hall Effect (), familiar hysteresis loop in the Hall Resistance/Resistivity vs. Magnetic Field plot. But In my case, the loops for various temperatures are found to be shifted downward, entirely in the negative y-region. Is it an artefact?
I have attached the plots of those results for your reference.
Have you been able to decompose the measured data into its longitudinal resistance and Hall resistance components? Typically it is pretty hard to measure 1 without having some component of the other. Having a shift in your data may mean that Rxx has changed and moved your loops up or down. If the magnetoresistance is pretty constant across these field regions, it may be the explanation.
Question
My set up is as follows : Elliptically polarized light at input -> Faraday Rotator -> Linear Polarizer (LP) -> Photodiode
The LP is set such that the power output is minimum. I use a lock -in-amplifier to measure the power change due to the Faraday effect. I have a more or less accurate measurement of the magnetic field and the length of the fiber. The experimental Faraday rotation (Rotation Theta= Verdet constant*MagneticField*Length of fiber) , is more than the theoretical prediction, so I was wondering if I am observing the effect of elliptical polarization at the input to the system.
Yes, you can say both polarizations get rotated. Taking each component separately, they both would get rotated by the same amount, and superposition applies, so together they do the sum of what each of the pieces would do.
However, if it helps, that is not the only way to think of it. We like to think in terms of linear polarization. We like to think of arbitrary polarization as a superposition of two orthogonal linear polarizations. It’s easy to make the diagrams. It also makes sense for linear polarizers and linear retarders. However, that is not the only choice. You can just as easily express an arbitrary polarization as the superposition of left and right circular polarizations. In the basis of right and left circular polarization a Faraday rotator is in fact a phase retarder. if the two components have equal amplitude the result is linear polarization. The relative phase determines the orientation of the linear polarization, so retarding the phase rotates the linear polarization. If the two components have different amplitude, you get an ellipse where the major and minor axes are the sum and difference of the amplitudes. Again, if you retard the phase, the whole ellipse just rotates.
As to why your experiment is producing answers that don’t quite seem right, I think this measurement has several things that can confuse the result. Although I don’t see why you wouldn’t put a polarizer on the entrance, I doubt the entering ellipticity is really the problem. That should just reduce your modulation amplitude making the signal a little weaker, but it shouldn’t impact the phase. A much more likely culprit is linear birefringence in the fiber. Fibers can have significant residual birefringence from the manufacturing, but also bending through the fiber acts as a retardation. For example, sequential coils of fiber called fiber paddles are sold as polarization manipulators.
Question
What are the size limitations of the mentioned measurements?
Can I perform these measurements on a pixel, let's say few microns to few dozen microns square?
Are there any limitations on the thickness?
Is there a major difference between 4PointProbe and Van Der Pauw measurements?
What is a reasonable magnetic field strength needed for Hall-Effect measurements and should it be relative to the probes lengths?
Thanks
Rh= 1/ne
n = 10^17 cm^-3
Vh = Ix Bz / Rh*w
w = 10^-6 (thin film)
Ix = 1 mA
Bz = 0.2 T
Vh = 1 mV to 1 V
The size of the contacts is 1 mm^2 , under 1 mm^2 is very difficult to make the contact
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I want to simulate the RF field around 10 Mhz in presence of magnetic field; looking for a tool that able to complete both the tasks together.
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Accordingly Wikipedia, books, and papers the magnetic pressure is B^2/2mu.
I think it is wrong, because not take into account the plasma speed.
We could obtain it for almost static magnetic field formula of movement of particles in a magnetic field, that happens usually if the magnetic field is under 10khz:
(H is the height of the plasma column, as lower height, more pressure)
The magnetic pressure equation mentioned assumes that MHD motion are slow compared to the speed of light. Please check explanation on eq 682 (click on it) and 688.
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I need to design a low-pass filter for cryogenic experiment. Ideally the filter should be placed near the sample. However, the sample will be subjected to high field up to 4 Tesla. How much this field will affect the pi-filter and/or RC-filter. The cryogenic temperature will be around 2K.
Grace Redhyka,
oh, I did not get that your Pi-filter has the inductor, I thought that Pi-filter is only composed from RC components. If there is also a magnetic device - inductor, than its properties critically depends on its core. If it is just an air-core inductor, than its inductance should not depend on external static magnetic field. If it is a feromagnetic-core inductor, than its core will be deeply saturated with 4 Tesla external static field and so that inefficient. Therefore, you should only use an inductor with an air core.
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I would like to know how when we change the direction of the magnetic field, the refractive indices of left and right circularly polarized light reverses, can someone tell how that happens mathematically???
This answer is from my research book (preprint):
"If the 0.5 Spin and the 6 dimensions in electrons (E:+-0.5x6/3) make an unstable dimension (`1`) on the interaction of the unstable Spin, and if there is another elementary particle with 1 dimension for Spin as a force and -5 dimensions in the dimensional set (M dimensional set/particle in the dimensional structure) while moving and replacing the Spin 1 dimension on the interactions of the -5 dimensions, then that elementary particle can try to attract 1 dimension from electrons as an entanglement between unstable dimensions making a cyclic process from that as making the Magnetic Monopoles. And that symmetric process could keep that elementary particle (M) as a relatively satisfied cyclic force, or Photons (P: -1x6/3) could give dimensions to fill M against electrons as an interaction between them (electromagnetism)."
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For the flow of nanofluid through duct, we an applied the magnetic field to study the enhancement of heat transfer using Ansys fluent. How I can do this, please I need documents, or video for tutorial.
Dear
Best
Dr. Ahmed Al-Manea
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I ran into a problem when measuring the RF magnetic field with a magnetic probe in a helicon discharge. I measure three field components with coils, using a balanced transformer to filter the capacitive pickup. The probe is located across the axis of the installation on a slide in the diverging field of the expansion volume (about 55 cm distance from discharge camera center). In most cases, the field profiles are not symmetric and do not fit any analytical solution (helicon antenna, m = + - 1). in addition, I found that the z field component changes its amplitude under the same conditions. What could be the reason?
By changing the amplitude do you mean changing its sign?. There can be an asymmetry in the magnetic field produced by the coil causing such an issue. Try using some Magnetostatic simulation code to map the magnetic field (CST studio, COMSOL,etc). It may give you a better and accurate analysis compared to a simple analytical solution.
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I am trying to observe TMOKE effect [T(+M) - T(-M)]/T(0) in COMSOL. Where T(+M) and T(-M) refer to Transmission of nanostructure in opposite magnetic field directions, and T(0) in absence of any magnetic field. For this I am using an Au nanostructure on a BIG(Bismuth-Iron-Garnet) magnetic material supported on SiO2 substrate. I have tried changing the magnetic field direction by changing the signs of off-diagonal elements in permittivity tensor for magnetic material but the results are unchanged. I have also rotated the structure so that magnetic field directions goes opposite but again the result is same. That is T(+M) and T(-M) are same leading to non existance of TMOKE. But the original paper I am following shows TMOKE. Can someone figure out the reason??? How to change magnetic field direction in this situation. For reference I have attached the research papaer.
Dear Muhammad Ikram, I hope you are safe and well!
Did you consider the off-diagonal values as: i*g?
You can consider i*m*g, where m is used in parametric sweep as -1, 0, 1.
It makes the magnetization inversion in a quickly way.
Further, what polarization are you exciting the structure? TM? TE? For TMOKE measures, it is important use TM wave and align the magnetic field component with the external magnetization. In 2D model, I usually set TM wave with Hz direction.
Best regards!
Question
Hello everyone,
I have a neodymium N42 grade 10mm thick 50mm diameter magnet with surface field of 2450 Gauss equal to 0.245 Tesla. Base on calculations, repellant force between two of them is about 72.3 lb at zero distance.
Now If instead of one magnet I put a same size coil with iron core over one magnet, how much force I can get with a pulse of 10 amperes of current pushing my neodymium magnet in stroke distance of 50 mm? Probably my coil should have over 1000 turns but the specification of coil is unknown to me.
What I need is the workable coil specs and the maximum repellant force I can get?
Thanks a lot
Many thanks for all your help. Till now you have shared very valuable information regarding my question. I'll go ahead with prototype in the desired form factor. All your general overviews helped me to come up with the best possible way to make this project work. Now I need to simulate the effect of two separate coils with desired specs to see how much force I can generate. I'll let you know the results.
Best of luck
Question
when a 2DEG is subjected to the magnetic field, the energy is split in the form of Landau levels. and the QHE is explained on that basis. however, in the case of quantized resistance is obtained without a magnetic field. then how Landau levels are formed in QSHE?
Dear Shlu,
As shown in 4he attached figure , the charge current flows from left to right through a conductor Hall bar. If the charge current is non-polarized (with equal numbers of spin-up and spin-down electrons), the spin imbalance does not induce a charge imbalance or transverse voltage at the Hall cross. If electrons, which are polarized in the direction of magnetization M, are injected from a ferromagnetic electrode while a circuit drives a charge current (I) to the left, a spin imbalance is created. This produces a spin current (IS) without a charge current to the right of the electrode. Spin–orbit interactions again separate spin-up and spin-down electrons, but now the excess of one spin type leads to a transverse charge imbalance and creates a spin Hall voltage, VSH. As the distance, L, between the electrode and the Hall cross increases, the voltage signal decreases, allowing the decay length of spin currents (spin diffusion length lsf) to be measured. More details about SQHE will be presented in Chapter 9 of my Book, about spin transport in nanostructures.
Question
An electron exhibits wave properties in some experiments and point particle properties in other experiments. This is designated “wave-particle duality”, but these are contradictory words. A wave has a wavelength and has energy distributed over a volume. A point particle has virtually no volume and energy concentrated at a point. Therefore, these contradictory properties cannot be equal parts of a single model. The electron model often associated with the Copenhagen interpretation of quantum mechanics is a point particle that achieves an electron’s wave-like probability distribution by discontinuous jumps. This is an example of a particle dominated model that is not fundamentally a wave.
Quantum field theory describes an electron as an “excitation” of the electron field. Such an excitation is sometimes illustrated as a localized wave oscillation on a sea of harmonic oscillators. This model is more wave dominated. The particle properties are achieved by the “collapse of the wave function” to deposit an electron’s properties (spin, charge, momentum, etc.) at a point when the wave-based electron is “observed”.
These are just incomplete examples to encourage discussion. What mental picture do you have of an electron? Does your model also address an electron’s electric/magnetic field that is distributed over a relatively large volume? Is the human intellect capable of conceptually understanding an electron?
Question
The magnetic field causes the orientation of single electrons of paramagnetic compounds in a specific direction. In the solution phase, does this matter affect the orientation and/or the order of the paramagnetic molecules?
Thanks,
Behnam Farid
for your response. But I can't understand the relationship of spin behavior (thermodynamic preference of a spin state) with the order of paramagnetic molecules in a solution, yet. In this regard, I can express my question in another way. Can we predict how the order of different kinds of paramagnetic molecules in a solution changes after a magnetic field is applied?
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Nearly a year ago, I hit upon an idea with which I try to make an analogy between the Coriolis force (F=2mv×Ω,) and the Lorentz force (F=qv×B) due to an induced magnetic field. I see that these forces are generally incapable of doing work since they are perpendicular to the curved path of the particle, and they are both proportional to the velocity of the particle. The only difference is that the Coriolis force acts on any particle regardless of whether it is charged or neutral, whereas the Lorentz force is exerted on charged particles.
I try to design a thought experiment in which the Coriolis force is entirely eliminated by a Lorentz force both acting on a charged particle. Can someone tell me if this idea is plausible or if there are some references regarding this matter?
Dr. Javanshiry, The commonality between the Coriolis force and the F = qvxB force is discussed in sections V and VI of this article,
This mainly discusses their common physical origins.
As for setting up a rotating system whereby a Coriolis force would cancel the magnetic force, it would be a matter of getting the correct geometry. I'm not sure though that this would be possible. The Coriolis force is a transverse force in a rotating system, whereas when the magnetic force is causing a charged particle to undergo circular motion, it is a radial force. I'm not sure how we could set up a rotation that would cancel this radial force.
But it's an interesting question.
Question
We know that an electron precesses when placed in an external magnetic field. It precesses with Larmor frequency. Does this precessing electron produce an electric field? If so how does it relate to the Larmor frequency? Any possible relation?
Dear Arbab:
At the first, and as you know that Protons and neutrons which are the constituents of atomic nuclei possess the quantum mechanical property of spin which has magnitude and direction. We can imagine these particles as if they were small spinning tops. As a result of spin, the nuclear particles act as small bar magnets. Inside the nucleus, these small magnets associated with the nucleons (protons and neutrons) line up so as to cancel each other's magnetic fields. However, if the number of nucleons is odd, the cancellation is not complete, and the nucleus possesses a net magnetic moment. Therefore, nuclei with an odd number of nucleons behave as tiny magnets. Hydrogen, which has a nucleus consisting of a single proton, does, of course, have a nuclear magnetic moment. The human body is made of mostly water and other hydrogen-containing molecules. Therefore, MRI images of structures within the body can be most effectively produced using the magnetic properties of the hydrogen nucleus. Our discussion will be restricted to the nuclear magnetic properties of hydrogen.
Normally, the little nuclear magnets in bulk material are randomized in space as is shown in Fig.(a) and the material does not possess a net magnetic moment (M=0). The nuclear magnets are represented as small arrows. However, the situation is altered in the presence of an external magnetic field. When an external magnetic field is applied to a material possessing nuclear magnetic moments, the tiny nuclear magnets line up either parallel or antiparallel with the magnetic field as shown in Fig. (b). The direction of the external magnetic field is usually designated as the z-axis. As shown in the figure, the x-y plane is orthogonal to the z-axis. Because the nuclear magnets parallel to the field (+z) have a somewhat lower energy than those that are antiparallel (-z), more of the nuclei are in the parallel state than in the antiparallel state. In an external magnetic field, the assembly of parallel/antiparallel nuclear spins as a whole has a net magnetic moment M that behaves as a magnet pointing in the direction of the magnetic field.
The energy spacing ΔEm between the parallel and antiparallel alignments is
ΔEm=γhB2π
Here B is the externally applied magnetic field, h is the Planck constant as defined earlier, and γ is called gyromagnetic ratio which is a property of a given nucleus. Typically the strength of magnetic fields used in MRI is about 2 tesla (T). (By comparison, the strength of the magnetic field of the Earth is on the order of 10-4T.)
The discrete energy spacing ΔEm, between the two state makes this a resonant system. The frequency corresponding to the energy difference between the two states is called the Larmor frequency and is given by
fL=ΔEmh=γB2π
The gyromagnetic ratio γ for a proton is 2.68×108T-1sec-1. Magnetic fields used in MRI are typically in the range 1 to 4 T. The corresponding Larmor frequencies are about 43 to 170 MHz. These frequencies are in the radio frequency (RF) range, which are much lower than X-rays and do not disrupt living tissue.
If by some means the magnetic moment is displaced from the field, it will precess (rotate) around the field as a spinning top precesses in the gravitational field of the Earth. The frequency of precession is the Larmor frequency. The displacement of the magnetic moment is due to a reversal of alignment for some of the individual nuclear magnetic moments from parallel to antiparallel alignment. A displacement of 90° corresponds to equalizing the population of the spin up and spin down states. To reverse the alignment of antiparallel spins requires energy which must be supplied by an external source.
# For more details please check this valuable articles about the topic at:
I hope it will be helpful...
With my best regards...
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can someone point me towards any relevant literature on this? Thanks.
thanks for sharing the reference, I will look into it.
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Hello community!
I want to ask a question that might be pretty silly to some of you. In the magnetic induction equation, when we consider the external magnetic field, do we have to consider the magnetization of the medium too?
Let's suppose we have a liquid film at rest with an external transversal magnetic flux B0. The liquid will be magnetized, creating a magnetic flux B1 that will be proportional to the external one.
Let's assume that the liquid film starts to move. The relative motion of the liquid, which is assumed to be a ferromagnetic material, with respect to the external magnetic field will engender an induced current density field in the medium. In turn, the current will generate its own magnetic field. The creation of this secondary induced magnetic field b is generally described by the magnetic induction equation. In this equation, the unknown function B is assumed to be given by the sum of the external field B0 and the induced one b.
In the literature, people are not considering the magnetization field B1 in the magnetic induction equation. In my opinion, this is not a generally valid assumption, because it does not account for the penetration of the external magnetic field in the medium due to the magnetization. Moreover, for some materials, the magnetic flux field inside the medium would be even higher than the external one.
From a more physical perspective, the velocity field inside the liquid enters in contact with the magnetic field inside the medium, the one given by the external one multiplied by a constant factor given by the permeability of the material.
Thomas Breuer
The liquid is not an ionized material. It is assumed to be molten metal. The current is generated in accordance with the Maxwell–Faraday equation, even though the magnetic flux field is stationary the ferromagnetic medium is moving with respect to it.
The point which is puzzling me is that in the steady-state conditions the magnetic flux field inside the liquid would be proportional to the external one thanks to the appearance of a magnetization field, with a proportionality constant that depends on both the material and geometry properties of the medium. Now if we consider an unsteady condition, where the liquid is moving, there will be also an induced magnetic flux field b. This field is generally calculated with the magnetic diffusion equation, assuming the magnetic flux is given by the sum of the external field and the induced one. I do not understand because we do not consider the magnetic field inside the liquid due to the magnetization.
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Dear Colleagues,
Working with a composite material whose band gap is found to be 2.5 eV, the Hall effect experiment shows decrease in Hall voltage with increase in magnetic field.
Is it possible?
Thanks and Regards
N Das
Dear Behnam Farid,
Regards
N Das
Question
We have a rectangular cubic cavity that is about a few millimeters in size. We put a magnetic system inside this cavity. Then we apply a fixed and static magnetic field to it. We know that this system is full of spins. They will make a Precession motion in the presence of an external magnetic field. Forget them for a moment and assume a semi-classical vector instead. We know that ultimately the total energy of this system consists of the cavity energy and the energy of the magnetic system and the energy of the interaction of the two systems. The question is how to find the energy of the magnetic system.
Dear Parisa Maleki,
The energy of the magnetic system is dependent on the temperature of the cavity and the interaction with the applied field.
The magnetic energy of a single dipole is -μ.Β. So, if there are N total number of dipoles and n number of dipoles are oriented along the field, then the magnetic energy of the system is n( -μΒ) + ( N-n)( μB).
The value of n depends on temperature.
Thanks
N Das
Question
While solving for the electric and magnetic wave components using Maxwell's equations in the free space, I have read that it was assumed that propagation of the wave is in z direction and that all the field components in this direction may be expressed in the form e^(-r*z) where r is a complex number. It is stated that it is a reasonable assumption for any uniform transmission guide. Why is it so?
And what does the term 'propagating in z direction' mathematically mean, with respect to the solution obtained for each field component through variable separable method where the solution is in the form of the product of a separate functions each of which is a function (constant * exponential) of just one independent variable?
Favourite Discussion
Good luck
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When superparamagnetic particles in a ferrofluid are converted to a thin-film and influenced by a strong magnetic field, they form micron-sized chains. I have searched the internet for images of these chains at the 200 nm resolution level while influenced by a field, but have not found any.
If you have the capabilities to examine a pre-made cell at this level and want to collaborate on a dynamic magneto-optic paper, please message me and we can make arrangements for me to ship a Ferrocell to you at no cost.
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I am conducting a CO2 electrolysis experiment in aqueous medium, where I will be stirring the medium with a magnetic stirrer. I read in the paper linked below that a perpendicular magnetic field (to the surface of the electrode) of more than 1 T can improve bubble dispersion and thus solubility.
As I am stirring my medium with a magnetic stirrer, I was wondering whether such effect would apply to my system. But I am not sure about the strength and direction of the magnetic field generated by the magnetic induction stirrer. Is it ≥ 1 Tesla? And what is its direction?
Thanks
The discussed equipment is ordinary magnetic stirrer for liquids in which a magnetic piece rotates due to the magnetic field of another. The rotation of the latter is controlled electrically. For electrically operated small magnetic stirrer the field would be ~ 1kG but not ~1T.
Since the medium is field sensitive, it is desirable to measure the magnetic field by a guass-meter.
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I was looking for some sources (if available), which contain information about geomagnetic events, ICMEs, Flares, SEPs during the different encounters by Parker Solar Probe (PSP). I am working on the analysis of abrupt fluctuation in solar wind parameters during the encounters by PSP. I would really appreciate your suggestions. :)
For my work on CMES, I used Richardson and Cane catalogue:
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I want to know how solar wind from a sun ( towards the earth) vary over a distance, specially during solar minimum period. Can you suggest some any related articles?
Try E.N. Parker's work (he first delineated the solar wind). I also suggest you go onto the NASA site for the Parker Probe and try looking up recommended papers that might answer your questions in their latest manifestations - and related sites from other solar probes that have been doing work on these matters over the last few years (there are several). And, good luck.
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