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# Electromagnetism - Science topic

Explore the latest questions and answers in Electromagnetism, and find Electromagnetism experts.

Questions related to Electromagnetism

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*(This also answers the criticism that the natural and the artificial shouldn't be mixed. The discussion takes the view that “natural” and “artificial/technological” are the same thing – and explains HOW they are the same thing)*Let's begin with a statement I read recently, “Special relativity is the most fundamental, and thoroughly proven, theory in all physics.” I won’t question that but I will suggest that we consider quantum gravity (QG). There’s no theory of quantum gravity at present but modern physics seems to have little doubt that we will have a successful theory one day. Despite the enormous success of general relativity, that theory will require adjustments to fit in with QG. Quantum mechanics will also need modifications to fit in, as Einstein realized when he called it incomplete. In all history, there has never been a single theory that could be called 100% perfect in the sense that it explained every detail forever, and never needed refinements – and there will never be such a theory. Our period of history is no different and that other product of Einstein’s brain (special relativity) has brought great advances but must inevitably endure the same fate of being refined.

May I suggest possible modifications to the above theories –

**not to attempt to compete with quantum mechanics or the relativity theories but merely to demonstrate that refinements of them are conceivable**.First, quantum mechanics –

Reliance on bodily senses – extended to our technology – tells us things and events are distinct and separate. Acknowledging the correctness of this frame of reference means there are countless particles forming the cosmos. Recognizing the truth of a different point of view means these particles are unified by the action of advanced and retarded waves into one particle* - whether it be classified as a boson or fermion (or both). The interpretation of particles being in two or more places at once can be reinterpreted as being in one position i.e. unipositional, from the Latin

**ūnus***meaning one. This unipositioned particle interferes with itself since it’s composed of self-intersecting Mobius strips which, because mass is united with spacetime, account for spacetime’s curvature. Unipositional quantum mechanics also means every particle is entangled with every other.** "When we solve (19th-century Scottish physicist James Clerk) Maxwell's equations for light, we find not one but two solutions: a 'retarded' wave, which represents the standard motion of light from one point to another; but also an 'advanced' wave, where the light beam goes backward in time. Engineers have simply dismissed the advanced wave as a mathematical curiosity since the retarded waves so accurately predicted the behavior of radio, microwaves, TV, radar, and X-rays. But for physicists, the advanced wave has been a nagging problem for the past century."

("Physics of the Impossible" by Michio Kaku, 2009, Penguin Books, p. 276)

Second, addressing the subjects “non-causal” and “at once” –

All mass is composed of gravitational and electromagnetic waves, according to vector-tensor-scalar (VTS) geometry inspired by the title of Einstein's 1919 paper "Do gravitational fields play an essential role in the structure of elementary particles?" Both types of waves possess retarded and advanced components which cancel each other and entangle all masses. Wick rotation (time) is built into the Mobius strips and figure-8 Klein bottles composing (respectively) electromagnetism's photons and gravitation's gravitons. Therefore, all time (the entire past and present and future) is united into one thing just as all space and all mass are united into one thing. If time only passed rectilinearly - from past to present to future - the idea of waves travelling back in time would make no sense at all. But if time is curvilinear - with past, present, and future interconnected - time must be able to move from future to present to past.

**(Unity of past/present/future may remove the issue of non-simultaneity – in special relativity – because the timing or sequence of events being different in different frames of reference can only exist if past/present/future are separate. The concepts of cause and effect are no longer separate when all periods of time are united, and everything can happen “at once”. This is similar to watching a DVD – every event on the DVD exists at once since the whole DVD exists but we’re only aware of sights and sounds occurring in each tiny fraction of a second.)**

Third, proposing faster-than-light travel (a feature of special relativity is light-speed as the universal speed limit).

The Riemann hypothesis, proposed in 1859 by the German mathematician Georg Friedrich Bernhard Riemann, is fascinating. It seems to fit these ideas on various subjects in physics very well. The Riemann hypothesis doesn’t just apply to the distribution of prime numbers but can also apply to the fundamental structure of the mathematical universe’s space-time. Cosmic maths incorporates

1) topology (the two-dimensional Mobius strip and figure-8 Klein bottle which is immersed [not embedded] in three dimensions),

2) BITS aka electronics’ BInary digiTS, or base 2 maths, which encode the topology,

3) the real and imaginary numbers of Wick rotation (time),

4) vector-tensor-scalar geometry, describing interaction between photons and gravitons, and

5) the Mobius Matrix, combining the topological Mobius and mathematics' Matrix to explain higher dimensions.

How does the Riemann Hypothesis support Faster-Than-Light travel?

*Answer – Using the axiom that there indeed are infinitely many nontrivial zeros on the critical line (calculations have confirmed the hypothesis to be true to over 13 trillion places), the critical line is identified as the y-axis of Wick rotation (stated above to be the time component of space-time). This suggests the y-axis is literally infinite and that infinity equals zero. In this case, it is zero distance in time and space. Travelling zero distance is done instantly and is therefore faster-than-light travel.*

*It must be stressed again that I’m not saying the above ideas are either correct or incorrect. I’m merely seeking to show that modifications to special relativity, general relativity, and quantum mechanics are indeed possible!*I am a PhD in mathematical modeling and never studied applications in diabetes treatment.

However, by particular reasons, I was searching some new researches in the area. In fact, I've found some people doing electromagnetism tests to promote better life quality to patients. It seems fantastic to me.

I am interested in learn more about it. Some researcher can indicate me some new trend?

Thank you!

This morning, I found a couple of paragraphs in a book I had published a year ago which made me wonder if the EmDrive, EM Drive or radio frequency (RF) resonant cavity thruster should be renamed the Possible Engine. I don't know if these are more deep thoughts or if it's just my subconscious telling me I have a secret crush on Supergirl 📷 but here are those 2 paragraphs -

"British engineer Roger Shawyer proposed the EmDrive, EM Drive or radio frequency (RF) resonant cavity thruster in 1999 and it's claimed to use patented microwave technology which converts electrical energy into thrust by amplification of the microwaves creating pressure which drives the vehicle's front forwards. Light is one form of electromagnetism – microwaves are another (so they also obey James Clerk Maxwell's electromagnetic laws and their solution for both retarded and advanced components of the waves).* So some of the microwaves are advanced, and travelling back in time.^ To this action, there is - agreeing with Isaac Newton's 3rd law of motion - an equal and opposing reaction i.e. a thrust forward in time. Since space can never be regarded separately from time, an object in space is affected and the forward thrust in time could power a spacecraft through the void via the EM Drive.

* Gravitational waves must also have advanced and retarded portions. Einstein's equations say gravitational fields carry enough information about electromagnetism to allow Maxwell's equations to be restated in terms of these gravitational fields. This was discovered by the mathematical physicist George Yuri Rainich. [George Yuri Rainich, Transactions of the American Mathematical Society, 27, 106 - Rainich, G. Y. (1925)]

^ The attached "Topological Propulsion Through Space-time" should explain how advanced waves are indeed possible.

"What are the consequences if gravitational fields play an essential role in the structure of elementary particles,** and if gravitational waves can travel back in time? Then the equal and opposite reaction providing the forward thrust in time could not only "power a spacecraft through the void", but it could power anything with gravitational waves in its composition. This includes giving controlled flight to Superman and Supergirl, without any jetpacks - acting in a manner similar to the proposed method of EmDrive, superbeings would be powered through the air."

** The section about vector-tensor-scalar geometry in "Topological Propulsion ..." explains the relation between gravitational fields and elementary particles.

"Out of Time - Predicting the Science of Future Centuries and Millennia (Edition 2)", 19 October 2021, Page 1-93 https://doi.org/10.9734/bpi/mono/978-93-5547-061-4

I know that the electric field inside a charged conducting shell is zero. However, what if we accelerate the shell uniformly? Does the charge distribution remain uniform? If not, is it possible for the new charge distribution to allow some electric field to penetrate the conducting shell?

I guess that the shell still resists the electric fields to be penetrated inside it even if the shell is accelerated, however, I cannot prove it.

Are there any students or professors with students interested in helping with research of Bob Lazar's Sport Model? I don't have much money, just the thrill of a whole new field of study, specifically , a link between electromagnetism and gravity. For more information, please see the attached presentation. Skip over project 1 and see project 2 and 3 used together at the end of the file. This research is for people with experience with microwave RF and microwave magnetic materials.

The refractive index is obtained owing to classical electrodynamics. Is there any way to know how much momentum the electron gains when light incident on a dielectric material? How does the momentum of the electron depend on the refractive index ?

I have the dimensions of an electromagnet comprising a 0.8mm diameter copper wire, which is used to make a coils around 11mm X 13 mm rectangular cross section core material. The dimensions of the coil after wounding around the core is 25mm X 23mm cross section and 17.6 mm height.

So, how to find the effective number of turns in this for calculating M.M.F and also what other properties can be calcuated from this?

Inertia, by definition, is a concept of measuring the “change”, the resistance, in the “natural state” of a body in motion. Is it thus correct to suggest that the idea of a “natural state” is exactly what a theory of everything would entail, and thus would not include the idea of “inertia”, would not include the deliberate man-made “changing” of bodies in motion, bodies in motion that would ideally primarily yield to fundamental field forces? Is not “inertia” a man-made theoretical concept to highlight how we are able to “resist” bodies in motion, to change the natural course of mass, as a “disruptor” within an otherwise ideal “theory of everything” manifest as the natural state of reality? The big question is then, “can using the idea of inertia provide for a link between the most fundamental field forces of gravity and electromagnetism” in achieving a grand unified field force theory of time and space?

*This paper is a project to build a new function. I will propose a form of this function and I let people help me to develop the idea of this project, and in the same time we will try to applied this function in other sciences as quantum mechanics, probability, electronics …*

Hi,

Is there any tips that can make finding modes for fibers, such as photonic crystal fibers, an easy process?

Thanks.

I am looking for a Hall effect sensor that can be interfaced with the Arduino board for measuring the flux densities of permanent magnets(NdFeB 40, NdFeB 42 etc.) at varying distances from the Magnet's surface.

I am looking for a solid core material for DC electromagnet design, but could not find any. I found only hiperco 50 material, but it's price 123$/kg too expensive. Would you suggest me suitable and avaliable core material on the market.

The waelength of the CMBR is about 10^-3 metres, what is the longest wavelenght or lowest frequency of electromagnetism detected

*in a vacuum*.**Please**do not include ULF electromagnetic frequecies as these have to go through a solid (the planet Earth)

Many thanks in advance for your replies

Can I please ask for good articles/papers/ thesis on Flat Lens Antenna to study? Is it metamaterial or antenna having a metamaterial at the back?

I am looking at this:

Trying to understand what is this?

Thank you

If you had a design for an electromagnet core that required it to be assembled out of several parts would it still produce as strong a magnetic field as the same core but made out of a single piece?

My thinking is that the magnetisation may not be as effective across the boundary between two metal components that are touching as opposed to a solid piece of metal but I am unsure as to how detrimental that would actually be.

I need some help. I am involved in calculating numerically the potential and electric field solutions in the 3D space of the classical problem of a disk with radius r0, biased at potential V0, surrounded by a circular crown of a flat dielectric (from r0 to rb), and this in turn by a flat infinite conductor at V=0. The three elements are located, for convenience, in the Z=0 plane, and the disk axis coincides with the Z axis (angular or acimutal symmetry).

I realize this is a problem involving 3 boundary conditions in separate domains, and with 'hybrid' character, because in the dielectric the only thing we can say is that the vertical component of the electric field (Ez), or potential derivative in the z direction (dV/dz), is null (by smmetry). This is what literature considers an "triple integral equation system with hybrid boundary conditions".

I follow the guidelines proposed in books and formulate the solution for the potencial V(r, z=0)

*in the dielectric region*in terms of series of Bessel functions.My problem is that I am able to solve the series coefficients for V defining a domain for the Bessel funtions up to a distance rh > rb (well inside the grounded conductor),

**without using the hybrid boundary condition dV/dz=0.**In fact, the problem is that my solution meets well the condition V(r)= V0 (for 0 < r < r0), and V(r)=0 (for rb < r < rh), but does not meet the condition dV/dz = 0 in r0 < r <rb. If I try to impose this condition, apparently the only solution is the trivial one, null.**What am I doing wrong?**(I know the analytical solutions of the triple integral equation system proposed by Duffy for the so-called A(k) function, but I wanted to formulate the problem in terms of discrete series, and not continuos functions). Can someone help me with this?

Wavelength of light is an obvious factor, but this is not my point of question

Some specific questions are

- What can be molecular/atomic level mechanism behind temperature and density dependence of refractive index?
- refractive index is square root of product of relative (electric) permittivity and relative (magnetic) permeability of a medium. How a ceramic/glass/polymer structure can attain high relative permittivity (higher dielectric constant means more polar groups in polymers, more charge imbalance in ceramics) and high relative permeability (aromatic groups and ferromagnetic ligand centers in polymers, second one also for ceramics) without losing transparency?
- how phase angle of complex permittivity and permeability of a medium depends upon its structure (e.g. factors mentioned above, bulk of chain and steric effect in polymers, photon propagation and phonon-mediated dipole oscillation of ceramics, chemical substitutions in ceramic structure)?
- Why some atoms elevate refractive index of ceramics and some substituent groups elevate refractive index of polymers more than others? While atomic/ionic polarizability can be explained from fajan's rule and pearson's HSAB theory, and magnetic behaviors can be explained from magnetic spin, electronic configuration (and spin exchange between nearby atoms); have there been any comprehensive work combining all these aspects to predict refractive index elevation?

if there is somebody who can help me with modeling an electromagnet 12V Dc and a piece of material placed on the electromagnet core to study the effect of current flux on the mechanical properties of the material.

I made an iron powder core of the following specifications:

Radius : 65mm

Length : 10mm

Mass of iron used : 10% mass fraction (20g)

Total mass : 200g

Binder : Slow cure epoxy

I noticed that after curing, the iron powdered settled at the bottom and formed a thin layer. The core also did not increased the magnetic field strength of the magnet. As I don't have enough epoxy to make more cores, I'm wondering if anyone know if the lack of improvement is due to the amount of iron used, the fact that the iron settled at the bottom of something else I may not have considered.

Any help or tip is very much appreciated. Thanks !

Looking for some good FEA software that is not cost prohibitive.

I am looking for benchmarks in educational studies that investigated the benefits, obstacles and disadvantages regarding the use of simulation software to support teaching at undergraduate level. It would be interesting to see results both from a teaching perspective as well as the learning outcomes and benefits to the students' understanding of STEM. It could be applied to any field in which simulation software is used (structures, fluids, electromagnetism, etc).

Dear Sirs,

I think many knows the ideas due to Jules Henri Poincaré that the physics laws can be formally rewriten as a space-time curvature or as new geometry solely without forces. It is because the physics laws and geometry laws only together are verified in the experiment. So we can arbitrary choose the one of them.

Do you know any works, researchers who realized this idea. I understand that it is just fantasy as it is not proved in the experiment for all forces excepting gravitation.

Do you know works where three Newtons laws are rewritten as just space-time curvature or 5D space curvature or the like without FORCES. Kaluzi-Klein theory is only about electricity.

Hi,

I'm attempting to create nonlinear metamaterial structures in comsol and I don't know how to measure second harmonic generation.

How do I measure that frequency x goes into structure and generates frequency 2x ?

Thanks for any help.

Is there any software (preferably MATLAB) for computing the E field resulting from a short dipole above a stratified media? I found something for a line source, but not a dipole.

The general term of the current reads

J_total=J_conduction+J_Displacement.

Where in most cases J_C obeys Ohms law and J_D=epsilon dE/dt.

Usually when a capacitor is disconnected from the electric circuit the the condition current is zero and so is J_t=0.

What will happened if I now intentionally adding a time dependent electric field between the capacitor plates (not sure if it's possible so it may be considered as a though experiment)?

My thought is that J_C will cancel somehow the displacement current in order to maintain J_t=0 since there can't be current outside the capacitor.

Is this analysis true or false? am I missing something? What is the meaning of conduction current in this case?

I need to build a continuous electromagnet, B=1-2 T, narrow hysteresis loop, good linearity (to have the flux density easily adjustable). Application - MeV electron beam deflection. I'll be grateful for any advice.

I am following the below method so far & need guidance to further modify it:

**1) Making a specimen**

**2) Making an Electromagnet using prepared specimen**

**3) Using DC & AC Source to find BH- Curve**

**4) Calculate Permeability from graph by taking respective points**

Please make your suggestions regarding all 4 points

Most people say that electro-magnet of strength more than 2 Tesla is not possible without superconductor.

Please tell me why ?

Regards

Nityananda Das

Is it possible to make a 4 Tesla or 5 Tesla magnet at 5 mm air gap. Air cooled.

Regards

Nityananda Das

Estoy trabajando con algunos alumnos Elementos Finitos para Electromagnetismo. Me interesa también la formulación con formas diferenciales.

Me gustaría hiciéramos un trabajo entre grupos.

Me escribes cuando puedas cpiedrahita@udem.edu.co.

Saludos cordiales,

CarlosP

In an electromagnetic field the flow of energy is given by the Poynting vector. For an electromagnetic wave, this vector is in the direction of propagation and accounts for radiation pressure. However, in a static electromagnetic field the Poynting vector can of course be non-zero. It's not easy to understand how there can be a 'flow' of energy in a static situation. Please discuss.

Hi, everyone! I want to use fluent's MHD module to simulate, using electromagnet to generate a rotating magnetic field, which can induce current in liquid metal and make liquid metal flow. How can I add the time-varying rotating magnetic field to the MHD module? How to write magnetic field files in .mag form? Can anyone help me out?

Does anyone know if the poisson solver will enable the calculation of capacitance between electrodes with a cylindrical structure?

Bonnor and Bondi suggest that GR predicts antigravitational interactions between negative masses. Jame Farnes points out that Newtonian mechanics suggest the same. But in electromagnetism interactions, same particles sign results in the same interaction, and only different signs behave different. Why choose one insted of the other?

Hi,

I'm trying to couple electrical circuit physics with frequency domain em wave.

In my simulation a wave of some frequency propagates through a split ring meta atom.

I have set lumped ports in the split gap of my split ring, and am attempting to connect a circuit element in my split gap to my split ring (eventually attempt to mimic a varactor diode but for now just a diode +resistor combination will do).

Whenever I run this, I get:

Failed to find a solution.

Maximum number of Newton iterations reached.

Returned solution is not converged.

Even if I change the iterations to 100/200 etc and even if I increase my relative tolerance.

I have tried a fine mesh and it takes a very long time and still has the same issue.

Any suggestions for helping the simulation converge?

Or even tips for linking circuit elements to 3d models in comsol as I'm new to the whole coupling physics functionality.

Thanks!

Hello,

I would like to know how to deduce the amount of current flowing through a solid volume , when current is applied in the form of current density 'J' (A/m2).

Example: As shown in the image attached, the solid body is a rectangular volume which acts as a coil in a electromagnet. In the simulation model I am building , the current flowing through the coil has to be input in terms of current density. The total volume is about 4.5 x e-6 m3 . A current density of 1e6 A/m2 is applied to the body.

As current density J=I/A , if applied to a 2D surface area, it is pretty straight forward to calculate the current flowing through the area.

What is the formulation to calculate the current in amperes for the volume?

Hi folks,

I am going to find the band structure of a 1D photonic crystal waveguide by COMSOL. There is an example in application library for 2D photonic crystal with a 2D geometry. In the example the refractive index of materials are frequency dependent, and a nonlinear formulation is used to normalize the field in a unit cell and finding the frequency and so updating refractive indices. It is exactly the point that I need to understand completely, since material dispersion is important for me, too. However, I can not figure out how the nonlinear formulation for the field normalization works and how I can utilize the same principle for a 3D geometry. I would be really grateful if somebody can help me.

Thanks for your attention,

Zeinab

Dear all:

I hope someone can give me some insight to this problem.

Considering that I have a micro size metallic particle. Lets say a symmetric Gold cubic particle, about 6 micrometers of lenght.

What physical framework do I have to use if I want to find the Electric Field distribution coming out from this particle ?

Will Maxwell Equations be enough for this case ? Ohm's Law ? some consideration of some Quantum Mechanical Effects ? Consideration of Plasmons ?

I'am posing this problem cuz I'm attempting to solve an Octahedral Gold particle of these dimensions in COMSOL Multiphysics, where I need to compute the E field distribution. Therefore I continue thinking if is as straightforward as to set the system of linear PDEs using just Maxwell Equations and Ohm's Law, and obtain physical representative results.

Please, any insight will be helpful

Regards ! :)

Hello everyone,

I am searching for references in numerical modelling of

**fully-coupled electromagnetism**with FEM for high frequency applications? I am particularly focussed on induction heating of magnetic polymers with hysteresis losses at high frequency alternating external magnetic fields.Any help is very much appreciated!

Thank you in advance!

The transformation of two "colliding" photons into a pair of particle / anti-particle was experimentally observed already. But the observed particles are always

*electrically*charged.1. If such a transformation takes place in vacuum, and the pair annihilates after a short time, then no interaction with other real particles occurs (apart from virtual particles in vacuum). If under these circumstances a pair of

*magnetically*charged particles were generated, could the mass of each particle roughly equal the mass of an "otherwise similar" electrically charged particle? I.e., if we permit the existence of magnetic monopoles at all for the moment, could we assume magnetic counterparts to electron and positron, for example, without immediately generating paradoxes? (The theoretical lower limit for the mass of magnetic monopoles in condensed matter is usually calculated as being much larger than the mass of an electron.)2. If magnetic monopoles were generated by photon/photon collisions, do you think they could be / would be detected under the standard experimental conditions? (For example, the usual spiral shaped paths would occur only in a strong electric field instead of the usual magnetic field. And besides that, the use of a cloud chamber is incompatible with the above assumption "no interaction with other real particles".)

3. If the anwer to question 2 is "no", do you know of attempts to observe magnetic monopoles generated by two photons? (If I'm not mistaken previous attempts to prove the existence of magnetic monopoles were directed toward single, relatively long-lasting monopoles, not necessarily generated inside the experimental setup.)

Many thanks in advance for answers and links to publications related to this topic!

Hi,

For a project I'm working on, I require an X band varactor, with a junction capacitance of the order of 0.1pF.

I am struggling to find a varactor (surface mounted, SC-79 packaging) with that low a junction capacitance, the best I have found so far is the SMV1430 by skyworks which has a junction cap. of 1.11pF.

Any help would be greatly appreciated.

Dear researchers and friends, please tell me the formula for calculating Reflection loss in EMI SE? I used 20 log [S11], is it correct?

The Pound–Rebka experiment is a well-known experiment to test Albert Einstein's theory of general relativity in 1959. The result confirmed the predictions of general relativity. Proponents of the theory of general relativity offer three different conflicting explanations of these results that are said to be equivalent to each other and therefore are all equally correct. The main problem with this explanation lies in the conceptualization of a physical process by which mass, momentum and energy could be either added to or subtracted from a photon without changing its velocity or angular momentum. Such a mechanism has never been proposed except for a mathematical description of a four-dimensional substance called a “space-time continuum.” This is a non-Doppler explanation of the shifts in which both source, observer and all photons are in the same inertial reference frame and the photons move at exactly c relative to both source and observer.

Apparent Weight of Photons; Physical Review Letters - PHYS REV LETT , vol. 4, no. 7, pp. 337-341, 1960

Take one electromagnet and a permanent magnet. Apply the current to the electromagnet for repulsion. Try to get them repelled at small separation. You will always find that corners of both of the electromagnet and permanent magnet attract each other instead of repelling. At lower current the attraction will be heavy and at higher current it will be weaker.

On the other hand, I have found that the majority of scientists deny the attraction between the like poles. I have discussed this matter with a group of scientists. Opinion of one of the scientist about this matter:

*“The strength and direction of a magnetic field at any point is the vector sum of all the individual fields at that point, so the situation you describe is not possible as the field at any point will always be a single vector. So it is not possible for the unaligned domains to be attracted by the permanent magnet while other domains are repelled because the unaligned domains will be acted upon only by the net field.”*Link to the discussion: https://www.thenakedscientists.com/forum/index.php?topic=75622.msg564049#msg564049Why is this obvious contradiction between the experimental fact and the opinion of the scientist?

Hello everyone,

This question is about the engineering feasibility of destining such a big electromagnet. I am a computational scientist and all I can think is stacking parallel current loops...The field is needed for ~1-2 micro second. So, it is enough if the electromagnet produces the pulsating field during 5 microsecond time window. The field need not be super uniform and preferably not using any ferro-magnetic materials. This is indeed contemplated for accelerator/collider experiments, so wild imaginations are fine :)

Can anyone please shed light on this?

Regards,

Kolahal

Capacitors and dielectrics pertain electric phenomena, one could say that inductors can be considered analogues of capacitors in the magnetic case.

Is there a dielectric analogue in magnetism?

What about dielectric relaxation in electricity, is there any such thing as magnetic relaxation? Can it be magnetic hysteresis?

I try to simulate 2D voltage induced in coil by moving magnet which is COMSOL example in 3D but I get error that Failed to evaluate variable Jacobian.

- Variable: comp1.tAx_lmTy

- Geometry: 1

- Boundary: 11 12 16 17?

An eddy current is a well known reaction in electromagnetism. They exist in the ferromagnetic core of various static and moving electromagnetic induction based machines, for example, transformers and motors.

**Is it possible to directly measure eddy currents?**electric flux density is equal to (numerically ) to the charge per area

_{.....}_{but what are those lines ?? , the electric field strength is represented by lines .... however such lines do not exist ..... eventually is there a particle that mediates magnetic flux, electric field strength or electric flux .... eg protons mediates charge ...etc}

I have a system set up where 35 mm cell culture dishes are placed in between 2 electromagnets. We want to use the maximum voltage the magnets are rated for to create the strongest field strength possible, but we are running into serious heating issues leading cell death throughout the dish. Does anyone know of a way to mitigate this issue?

Collective effects are evident in billions and billions of particles or entities in physics, such as In lasers, electromagnetism [1], superconductivity, critical mass in nuclear physics, physics of fluids, thixotropic and other non-newtonian effects, fusion and fission, binding energy, gravity, and quantum mechanics.

There are applications also in maths. We discussed its application in social movements, where statistics is not used, nor psychology, but a causal model is introduced, based on physics of fluids and collective effects.

The problem is that a system made of billions of billions of particles or entities, as usual in physics of natural systems, is much harder to study, for example, in quantum behaviour or even classical.

In network theory, comes the example of 6 degrees of separation. Now, in physics [2,3], comes the example of 10 photons. Studying quantum behaviour of particles is much easier with fewer particles, so the fact that phase transitions occur in these small systems means we can better study quantum properties such as coherence.

Could we start to see behaviour of collective effects with 10 electrons or less? Can we use them to better study coherence also in non-quantum behaviour? What is the lower limit?

[1] Carver Mead, Collective Electrodynamics: Quantum Foundations of Electromagnetism,

[3] Driven-dissipative non-equilibrium Bose–Einstein condensation of less than ten photons, https://www.nature.com/articles/s41567-018-0270-1

Of course, one can use Clifford Algebra Cl(3,1) in electromagnetism. But then, one is not working with Gibbs vectors anymore (NOTE 1.1, 1.2) , but with multivectors (NOTE 2.1, 2.2, 2.3). Better yet, we can try to check with tensors. There is a physics fundamental reason (NOTE 1.31P) why tensors are better than Cl(3,1) when one transforms coordinates.

Also, every element of a geometric algebra, such as Cl(3,1) and spacetime algebra by Hestenes, can be identified with a tensor, but not every tensor can be identified with an element of a geometric algebra. In that sense, tensors are more general than pure grade multivectors. The rank of a tensor is not restricted by the dimension of the base vector space like the grade of a multivector.

This means that there is no way to represent any 2nd-rank tensor by a bivector, vector, and scalar. Or, in particular, no way that any 3×3 matrix could be represented by a 2-vector in 3D!

So, it is not a 3D here and 1D there, but a union of the two, in 4D, that is desirable in electromagnetism spacetime. One can transform length into time, and vice-versa.

Tensors allow that, Cl(3,1) does NOT do that. And electromagnetism may be at least 4D, maybe 6D or more, which tensors can represent, but Cl(3,1) would not.

Similar question: what's the relationship of tensor and multivector . The short answer is that all multivectors are tensors, but not all tensors are multivectors, so geometric algebra is not and cannot be isomorphic to tensor algebra.

Therefore, geometric algebras (Clifford Cl(3,1), Hestenes) seem insufficient for electromagnetism, in all possible generality. What is your view?

NOTES:

1.1. The 3D vector cross product is not a vector, but a tensor. This is well-known and the reason to invalidate its use in Maxwell's equations, and physics equations. This is both a physical and a mathematical reason, commented below. But, would it not serve a restricted purpose adequately? No, it can create mistakes upon reference frame change, for example, simple mirroring, gives us wrong units in the SI MKS, worldwide, and this is all old news that have to be somehow continuously repeated, with a "life of its own," as a misconception in even current college books at competitive US universities.

1. 2. MATHEMATICAL REASON: The 3D vector cross product is not a closed operation in the 3D vector space, it produces a member that does not belong to the same set, the 3D vector space, although it may look like it in some cases.

1.3. PHYSICAL REASON: Both sides of an equation representing a physical relationship, such as A = B, must change equally when the frame of reference changes and the so-called inertial condition is obeyed, as already stated by Galileo, Newton, and Einstein, that

**the laws of physics are the same for all uniformly moving observers.**But if one writes an equation using a 3D vector cross product, such as A= B x C, the left and right side may transform differently if the coordinate frame of reference changes, while still inertial. In the past, this was accommodated, not solved, by considering spurious things such as polar and axial vectors, and pseudoscalars. This is solved using tensors, which maintain the form A = B under inertial reference change.2.1. Multivectors, in geometric algebras, or Clifford algebra, or Cl(n,1) algebras, or STA Hestenes algebra, solve the mathematical reason (1.2), creating a closed space in all operations. No geometric algebra operation is mathematically unsound.

2.2. Multivectors do not solve the physical reason (1.3), but tensors do. This is another reason, besides lack of isomorphism with tensors and no use of time as a coordinate in spacetime, that invalidates the use of geometric algebras in equations of physics, including electromagnetism.

2.3. With multivectors, If one eliminates the physically wrong results, by requiring an additional step of "filtering" through, let us say, a Hamiltonian, this will not produce those results that are physically valid but were ignored in the first place, using just multivectors. A sequence of filters cannot filter less than the first filter, well-known in physics, math, and engineering. This appears, more easily to see, in non-euclidean spaces, such as anything larger than, let us estimate in general, a few Planck lengths.

3. This thread arrived at a first conclusion, which is stated in the NOTES 1-2 above. There is no room to refuse to notice an obvious thing, or to re-explain here, the reasoning and references are available above, to anyone.

4. We are now moving on, to non-mathematical aspects of using Clifford algebras, even beyond the physical reason given in the NOTES above, where using Clifford algebras would be detrimental to special relativity. We are talking about time.

I am looking for a small electromagnet with a height of only 32 mm with cooling system and produce an out-of-plane magnetic field of about 2k Oe. Does any one know any brand which produces the small electromagnets.

In physics, spacetime mathematical models fuse the three dimensions of space and the one dimension of time into a single four-dimensional continuum.

The question asks whether the existence of a 4D model of the universe is necessary to UNDERSTAND special relativity or electromagnetism, as the Minkowski SR [1]. Not like Einstein SR, that results in inconsistencies that cannot be resolved within the system, and then beset the results.

[1] Minkowski SR uses spacetime to provide a clear pictorial representation for the special theory of relativity. See https://demonstrations.wolfram.com/MinkowskiSpacetime/

Does anyone has an idea on how to establish an electromagbetic control of a flexible and thin polymer (5-10 um thick)?

I think shrinking an electromagnet down to this size might not work. Is there a simplier way? would it work to have a coil on the “controller” and simply a magnetizable metal on the “probe that i want to move”? is there a limitation of size/dimensions this will work?

Thanks!

Hi everyone ;

I wish to draw the distribution of electric field amplitude and phase at a given distance from my patch antenna in cartesian coordinates.someone has already done!?

Thank you

I am trying to model Bulk-hetero junction solar cell using two physics module - Electromagnetism and semiconductor. while running the semiconductor module I am getting this error.

I have already checked my Boundary conditions.

Undefined value found.

- Detail: Undefined value found in the equation residual vector.

There are 188 degrees of freedom giving NaN/Inf in the vector for the variable comp1.Ne.

at coordinates: (-2.47032e-005,1.42627e-007), (-2.47019e-005,1.61237e-007), (-2.2932e-005,2.33333e-007), (-2.29348e-005,2.61008e-007), (-2.26355e-005,2.33331e-007), ...

There are 2357 degrees of freedom giving NaN/Inf in the vector for the variable comp1.Ph.

at coordinates: (-2.49918e-005,1.16766e-007), (-2.49776e-005,1.08352e-007), (-2.49918e-005,1.33433e-007), (-2.49351e-005,1.08365e-007), (-2.4956e-005,1.16717e-007), ...

Hi,

I am attempting to simulate in comsol a nonlinear metamaterial (which by using effective media theory I can approximate as a periodic slab of artificial material).

My process is as follows:

Run a frequency domain study, this contains my model, a propagating wave (from the emw port). I perform the comsol study and place domain point probes at points of interest. I monitor the Ex, Ey, Ez, and normE here.

Next, I find the voltage at a point in my material (at split of my split ring resonator) simply by multiplying a component of the E field at this point by the gap size of the split in the ring.

Next, I couple a time domain study of my model to a circuit model so I can apply a voltage source. I am looking for the second harmonic so I apply V(2w) =1/2 a(Vw)^2 voltage (from an expansion of the voltage in the linear model with 'a' being a nonlinear co-efficient which I will know).

Following this, I have a scattered boundary condition as a source of the field I have saved from my emw.Ey etc run from the frequency domain and I use a polarisation term to couple the incident field chi(2) *(emw.Ey)^2, where chi has been found via an equivalent circuit analysis.

I then export my time domain results to matlab (just for sake of ease as I'm more familiar with matlab) and take the abs(fft(Efield)) to find the frequency content of the output from my model.

I'm aware this method is probably incorrect, but any pointers, or corrections from correct comsol usage to correct method to simulate nonlinear materials, would be greatly appreciated.

Thank you very much

Capacitance of IDC depends on the dielectric material used in IDC. I think, capacitance is decreased with increasing frequency because at high frequency dielectric don't hold the charge so charge leakage problem comes. Please suggest me for this.

Hi,

I'm looking to predict via simulations and maths a nonlinear response from a square split ring meta atom to see if inserting a varactor across a split gap significantly changes the behaviour of the meta atom, and consequently how it changes, what kind of nonlinear susceptibility it presents and what kind of three wave mixing will occur. For now, I am only interested in up to second order responses.

I am using the Smith adaptation of the Nicholson-Ross-Weir parameter retrieval method to find the linear properties of the meta atom.

I am hoping to find expressions that I can use in Comsol, for the permittivity and permeability of the varactor diode that depend on frequency. Or, alternatively, some method of simulating the effect of the varactor diode without explicitly knowing the nonlinear susceptibility of the meta atom + varactor system.

This will hopefully allow me to measure the generated nonlinear waves even without directly knowing the nonlinear susceptibilities (as if I had actually done the experiment and measured the scattered fields). I can then continue on to a nonlinear retrieval method.

Any advice would be appreciated, even if it just helps me understand this process.

Thanks!

Hi,

I'm looking to draw copper tracks on a double sided substrate within a software that allows me to export as dxf/dwg/gerber for fabrication. Can anyone recommend a pcb design software that allows me to draw on copper tracks as oppose to just dragging and dropping circuit components?

Thanks

*As we know from the Electromagnetism that an accelerated charge particle always looses energy by radiating EM waves. Also from quantum theory we have t a minimum energy state i.e., ground state below which particle can't exist (hence can't loose energy anymore).*

*What resolves this apparant contradiction?*

*Please answer in brief, I already looked at some possible explainations which don't seems to answer this correctly.*

*Thank you in advance.*It is generally thought (see Special Relativity, A. P. French) that the magnetism we detect form an electric field, is related to relative motion with respect to that field. Specifiically a moving current generates a magnetic field.

Does that also apply to the magnetic field generated in electromagnetism. Specifically does the magnetic field derive from the motion of the electric field.

Is it possible to describe Electromagnetism in a way such that the electric field is defined as the curl of a vector potential and the magnetic field is the grad of a scalar potential? Will such a theory be consistent?

Light is known to be massless in vacuum. However, when it enters a conductor, does it still have zero mass? In a transparent medium, the speed of light is less that c, which would imply that light acquired some mass. What is the mass of light when a conductor is accelerating?

1- If light behaves like a quantum particle inside a conductor, then its effective mass will be m=(1/2)*mu_0*hbar*sigma, sigma being the electric conductivity.

2- Under gravity the mass of light inside a conductor is mc^2=hbar*g/(2c), where g being the acceleration due to gravity.

The mass in 2 can be linked to that of Unruh and Hawking who relate it to thermal energy of the emitted radiation

(pi k_B T=hbar g/(2c)

Electric field.

There are many definitions for it. Let's use this one from Yahoo:

·

An electric field is a property that describes the space that surrounds electrically charged particles or that which is in the presence of a time-varying magnetic field. This electric field exerts a force on other electrically charged objects. The concept of an electric field was introduced by Michael Faraday.

- Space surrounding a charged particle does not stop close to the particle but extends to universe.

- That means another charged particle millions km away experience a force immediately; something went faster than light to that second particle. Wow… That is the theory and its seems absurd.

- Since in this concept, nothing is leaving the charged particle, there is nothing to intercept or nothing to stop travelling.

- It should not be possible to shield the electric field even with a faraday cage. But the faraday cage works very well.

- That means the facts are wrong and the theory is right; interesting but absurd again.

- The electric field has energy to be able to exerts a force on another charged object. Where does that energy comes from. It comes from empty space because before the object was charged, that space was void. That means void can have energy and interact with something. Nothing can interact with something. Let’s be serious and look at these more carefully.

- The math aspect of the field has been verified many times and seem to be ok. What is probably lacking is the explanation of what is really going on physically

- One author states that the field is only a concept to help in the math part. It is not a reality. Then what is the reality.

Is it possible to do an experiment to find out if something is leaving the charged object?