What is Electromagnetic: Definition and 1000 Discussions

Electromagnetism is a branch of physics involving the study of the electromagnetic force, a type of physical interaction that occurs between electrically charged particles. The electromagnetic force is carried by electromagnetic fields composed of electric fields and magnetic fields, and it is responsible for electromagnetic radiation such as light. It is one of the four fundamental interactions (commonly called forces) in nature, together with the strong interaction, the weak interaction, and gravitation. At high energy, the weak force and electromagnetic force are unified as a single electroweak force.

Electromagnetic phenomena are defined in terms of the electromagnetic force, sometimes called the Lorentz force, which includes both electricity and magnetism as different manifestations of the same phenomenon. The electromagnetic force plays a major role in determining the internal properties of most objects encountered in daily life. The electromagnetic attraction between atomic nuclei and their orbital electrons holds atoms together. Electromagnetic forces are responsible for the chemical bonds between atoms which create molecules, and intermolecular forces. The electromagnetic force governs all chemical processes, which arise from interactions between the electrons of neighboring atoms. Electromagnetism is very widely used in modern technology, and electromagnetic theory is the basis of electric power engineering and electronics including digital technology.
There are numerous mathematical descriptions of the electromagnetic field. Most prominently, Maxwell's equations describe how electric and magnetic fields are generated and altered by each other and by charges and currents.
The theoretical implications of electromagnetism, particularly the establishment of the speed of light based on properties of the "medium" of propagation (permeability and permittivity), led to the development of special relativity by Albert Einstein in 1905.

View More On Wikipedia.org
  1. S

    B Dimensional Spin Inspection

    We learn that the dimensions of spin coincide with the dimensions of other magnitudes, for example action and angular momentum. They also coincide with a purely electromagnetic dimensional form. Is the next. $$\left[spin\right] = \left[ electric \ resistance \right] \ \left[electric \ charge...
  2. C

    A Retarded time and advanced time (and binning)

    Hi! I am dealing with the propagation of electromagnetic emissions through the atmosphere. To quickly outline: Imagine some charge distribution flying at relativistic speeds and inducing a four-potential A. We define some retarded time at which the charges are at some positions, and calculate...
  3. Hill

    B Wi-Fi Interference: How Microwaves Can Affect Your Wireless Connection

    I have noticed that every time my microwave is ON, my Wi-Fi connection freezes. It comes back as soon as the microwave stops. Is it normal?
  4. J

    What is the New Concept About Common Mode Noise in Electrical Engineering?

    M.S in electrical engineering, Has a publication on IEEE titled “New Concept About Common Mode Noise”. I have extensive knowledge in electrical engineering, including quantum.
  5. P

    I Colorless Compounds and electromagnetic radiation

    I was trying to understand why some compounds appear colorless (transparent) and tried to give an explanation. I take benzene as an example: it is a chromophore group in which there is π-conjugation, so a certain energy gap is generated between HOMO and LUMO. This energy gap is such that in...
  6. R

    B Interpreting light as Maxwell's EM wave

    Sometimes I cannot imagine light as the popular Maxwell's blue and red electric and magnetic wave https://simply.science/images/content/physics/Electromagnetism/em_waves/emv.jpg but I found the image below to be the more accurate representation of how light actually looks like as waves...
  7. C

    Discover the Real Gem: Neoclassical Theory of Electromagnetic Interactions

    TL;DR Summary: Book: Neoclassical Theory of Electromagnetic Interactions - A Single Theory for Macroscopic and Microscopic Scales I've found the book of Babin & Figotin: Neoclassical Theory of Electromagnetic Interactions - A Single Theory for Macroscopic and Microscopic Scales. I like their...
  8. J

    Best way to measure magnetic waves for electromagnetic induction

    Hi all, Looking to measure some magnetic waves being generated at an electric coil. Freq is between 0-20kHz and magnitude is pretty small <1T. Any have suggestions for the best tool to measure and log data of this magnetic waveform? Googling around, I found meters like this: [Possible spam...
  9. cnh1995

    I Neil deGrasse Tyson on Nikola Tesla and electromagnetic energy

    I came across this video where Dr. Tyson talks about Nikola Tesla. Neil Tyson on Tesla. From 4:47 onwards, he says "We now send energy through wires", and talks about how bizarre it would be to walk around/stand in the way of such energy flow. Further he says the power transmission lines are...
  10. sinus

    I The Method of Images (Electromagnetism)

    Can anyone explain to me why grounded means zero electric potential. I confuse what's the relation between infinite ground conducting plane and its electric potential (the method of images). I have a several question: 1. Why the conductor plane must be infinite, while in reality there's no...
  11. C

    I A donut electromagnetic core comprises main section + movable section

    There is a short movable section of cylinder shape in a O-ring magnetic core with DC coil, of course, there are 2 air gaps between the movable section and stator main section. My question: if rotate the movable section, is there a bunch of twisted magnetic lines? The rotation does not change the...
  12. hagopbul

    I Asking about something that I read on electromagnetic force

    Hello All: read a paper related to electromagnetic force and its applications in acceleration of charges particles , some thing came up in it , they drive a force applied on the particle called Faraday force = [1/2B]* [dB/dt]*m*v B magnetic field , m mass of the particle , v the velocity of...
  13. P

    A Why electromagnetic tensor (Faraday 2-form) is exact? (and not closed)

    Following from Wikipedia, the covariant formulation of electromagnetic field involves postulating an electromagnetic field tensor(Faraday 2-form) F such that F=dA where A is a 1-form, which makes F an exact differential form. However, is there any specific reason for expecting F to be exact...
  14. James1238765

    I Time evolution of the electromagnetic wavefunction on a lattice

    The Maxwell wavefunction of a photon is given in [here] as follows: Because the curl operation mixes 3 different components, this wavefunction only works for a minimum of 3 space dimensions, with each grid point having 6 component numbers ##{E^1, E^2, E^3, B^1, B^2, B^3}##, and with the...
  15. A

    Electromagnetic linear momentum for a system of two moving charges

    When you write out the equations of motion for a system of two isolated charges, you can add both of the equations and get the increase in the particles linear momentum on one side. On the other side, you get the sum of all the forces between the particles. I understand that this sum of forces...
  16. A

    I Parameters of the rough surface (for electromagnetic scattering)

    Dear friends, I will be grateful if anyone can help me I study electromagnetic scattering by rough surfaces for a certain case. Each rough surface can be specified with the statistical parameters sigma (σ) and correlation length (lc). while writing my manuscript I drew a schematic...
  17. N

    I Can I send an electromagnetic wave to a specific point?

    Since I'm computer engineer and don't have much experiences with electromagnetism, I'd like to know if it is possible to make an electromagnetic signal (250khz - 500khz) and send it to a point (with an error of maximum 1cm) in a room. If yes which devices do I need to setup my experiment?
  18. C

    I Where do discontinuities in the electromagnetic field occur?

    Obviously at point charges, but where along boundaries? Would they theoretically occur in superconductors since they can carry infinite current (J -> infinity)?
  19. H

    Energy conservation: electromagnetic wave in matter

    Hi, I completely failed this homework. I mean I think I know what happen, but I don't know how to show it mathematically. The energy lost by the wave is used to oscillate the electrons inside the conductor. Thus, the electrons acts like some damped driven oscillators. I guess I have to find...
  20. C

    I Can Current Density Static Create an Effective Electromagnetic Shield?

    I've been thinking about electromagnetic shielding lately. Of course, you have your good, old-fashioned Faraday cage. But after staring at Maxwell's equations awhile, I'm thinking: We're after a static E field, right? So if we set ## \frac{\partial \textbf{E}}{\partial t}=0## in Ampere's...
  21. A

    B Doppler effect on electromagnetic waves in a car

    Is the doppler effect on electromagnetic waves receive by cell phone in fast car and so somebody talk with cell phone in fast car view this effect
  22. warhammer

    I Query on Electromagnetic Theory (Dielectric Boundary Conditions)

    The given question from Electromagnetic Theory (which is based on Dielectric Boundary Conditions) is as follows: Interface b/w two dielectric medium has a surface charge density (suppose xyz C / (m ^ 2) ). Using boundary condition find field in 1 (relative permittivity =xyz) if field in 2...
  23. P

    B Is a 'Brain Wave' a Real Wave?

    Can I say, by any means, that a "brain wave" is, in fact, a wave of some kind?
  24. J

    I Cosmic Inflation Explained: Constant Velocity of Electromagnetic Radiation

    C = sqrt(E/M)...this would suppose the ratio of the amount of energy vs. the amount of mass in the universe. If not, why not. If there is no mass, just energy, or much less mass at the moment of the hypothetical Big Bang, then, there C would be significantly higher, thus explaining cosmic...
  25. V

    How can the force of a normal reaction be electromagnetic?

    I do understand that gravitational the electromagnetic force between two electrons or protons is very large compared to the gravitational force between them. I can see this by looking at the equation of gravitational force (##F= \frac {Gm_1m_2} {r^2}##) and the equation of electrical force given...
  26. P

    I Energy of an electromagnetic wave

    The energy of an electromagnetic wave does not depend on the frequency of the wave, only on the amplitude. Then why is light with higher frequency more energetic than light with lower frequency?
  27. A

    I Electromagnetic effects in the brain

    good evening gentlemen, for some months I have a problem and maybe it depends on the wind turbines. I live in the countryside and there is a wind farm near my house, and when I am out gardening, when there is strong wind and the blades are spinning fast, I feel strange, as if I fall into a...
  28. H

    A Exploring Electromagnetic Induced Transparency in 85Rb Gas

    Hello,everyone! Recently i am doing an experiments about electromagnetic induced transparency in 85rubidum gas. I have two light source,which use the polarization spectrom frequncy stablizaiton technology to make them stable.One is used for probing light,and the other one is used for coupling...
  29. M

    I Constructive interference of harmonic electromagnetic waves

    Hello ! I have a doubt as to how is this case, if it occurs, of the constructive interference of two harmonic electromagnetic waves but of different wavelengths or frequencies between them. That is, if between the two electromagnetic waves a new and unique electromagnetic wave is created and...
  30. LUFER

    What is the Electromagnetic Cross Section in this plasma deposition process?

    What is Electromagnetic Cross Section? (shock section) Hello, I have a question regarding the manufacturing process of electronic components in the case of the silicon deposition and corrosion process. My biggest doubt is the behavior of the plasma interacting in the reactor, I don't know if...
  31. LCSphysicist

    Poynting theorem and electromagnetic density

    I am a little confused with the Poynting theorem https://en.wikipedia.org/wiki/Poynting%27s_theorem . When we use this equation, the energy density that enters in $$\partial u / \partial t$$ is the one due only to the fields generated by charges/source itself? That is, if we have a magnetic...
  32. S

    A Current Status of Electromagnetic Triviality

    I know how to calculate the standard Landau pole result at one loop suggesting that a quantum field theoretic treatment of the electromagnetic force in the continuum is trivial. I am wondering does this result continue to hold at higher loops, nonperturbatively or when electromagnetism is...
  33. ergospherical

    I Calculate Eigenvalues of Electromagnetic & Stress-Energy Tensors

    How can we (as nicely as possible... i.e. not via characteristic polynomial) calculate the eigenvalues of ##F_{ab} = \partial_a A_b -\partial_b A_a## and ##T_{ab} = F_{ac} {F_b}^c- (1/4) \eta_{ab} F^2 ## and what is their physical meaning?
  34. A

    Work and energy of electromagnetic wave with intensity I

    a) ##\rho = \frac{I}{c} = \frac{F}{A}## for a perfect absorber ##F = ma## where ##a = \frac{c}{t}## ##\frac{I}{c} = \frac{mc}{tA}## ##I = \frac{I^2 tA}{mc^2} = \frac{P}{A}## ##P = \frac{I^2 tA^2}{mc^2} = \frac{W}{t}## ##W = \frac{I^2 t^2A^2}{mc^2}## I am unsure what A is. I think it should be...
  35. M

    I Energy of Electromagnetic Waves in Destructive Interference

    Hello ! As we know by definition that: "Constructive interference occurs when the phase difference between the waves is an even multiple of π (180°), whereas destructive interference occurs when the difference is an odd multiple of π." But my question is in the case of destructive...
  36. C

    A Relation of Electromagnetic Field & Field Tensor

    hello, 1. according to Robert Wald, General Relativity, equation (4.2.22) the magnetic field as measured by an observer with 4-velocity ## v^b ## is given by ## B_a = - \frac {1}{2} {ϵ_{ab}}^{cd} F_{cd} v^b ## where ## {ϵ_{ab}}^{cd}##, the author says, is the totally antisymmetric tensor (for...
  37. A

    I Gravitational vs. Electromagnetic Waves: What's the Difference?

    in a nutshell what are the differences between gravitational and electromagnetic waves?
  38. Dom Tesilbirth

    The magnetic phase change of an electromagnetic wave during reflection

    If the question had mentioned ##\overrightarrow{E}## instead of ##E_\bot##, then we could have used ##\overrightarrow{B}=\dfrac{1}{v}\widehat{k}\times \overrightarrow{E}## to get the direction of the magnetic field. But the question had only mentioned ##E_\bot##. To my understanding, knowing...
  39. B

    I Incident electric field attenuation near a metallic plate

    Hello everybody, I was visualizing the electric field radiation pattern of an antenna in a 3D EM simulation software (CST), and to see it with my eyes made me realize something I probably heard during my studies but forgot. What is the phenomenon behind what you can see below, which is the...
  40. G

    B Can electromagnetic waves traverse wormholes?

    Hello I'm new to this forum and interested in astrophysics and metaphysics. My first question here is if we can create nano sized wormholes to send information faster than light to other stars for example. We don't need to travel if we could send small satellites or even just radiowaves to the...
  41. H

    I Group velocity for an electromagnetic wave inside glass

    Hi, I saw that the group velocity for an electromagnetic wave can be calculate with the following formula ##v_g = v_p + k \frac{d v_p}{dk}## Thus, since ##v_p = \frac{c}{n} = \frac{\omega}{k}## Is it correct to say that ##v_g = \frac{c}{n} + k(- \frac{\omega}{k^2})## where ##k =...
  42. samy4408

    B Question about electromagnetic waves -- Penetration vs. Frequency

    I read in a book that high frequency electromagnetic waves are more able to penetrate than low ones , so why radio waves can penetrate walls when light cannot?
  43. B

    I Estimation of E-field strength at a distance from dipole antenna

    Hello everyone, I was asking myself about electric field strength estimation at a distance d from - in my case - a half wave dipole antenna. There are pretty much a lot of information about this on internet or in books but still, there are a few things that are confusing to me that I would...
  44. rudransh verma

    Contact and electromagnetic force

    I don’t know what is contact force. Are friction and normal forces called contact forces? And we have to take the resultant of the two to get the net contact force?
  45. G

    I Information content in electromagnetic or gravitational waves

    Electromagnetic or gravitational wave carries energy and momentum from place to place as,I understand.Does it imply that such waves only can carry information and if their energy gets dissipated as heat, the information contained is lost. Is this information content is to be decoded by human...
  46. rudransh verma

    B Is the Kink in the Electromagnetic Wave Responsible for Delayed Motion?

    I was reading Six easy pieces from Feynman and I got stuck what is electromagnetism 2 years ago. Recently I came across a video and I think I have figured it out. The paragraph says like this: “ If we were to charge a body, say a comb, electrically, and then place a charged piece of paper at...
  47. M

    Amplify ferrite core solenoid electromagnetic range

    Hello all, I'm playing around with a PIC + LCC Tank to send - at a 5MHz frecuency - some numeric data via BPSK. The receiver is a loop antenna placed in the ground. The sender antena (L) is a ferrite core solenoid (N=10). As having a larger core, or increasing the Number of coils around the...
  48. Konte

    I Quantization of the electromagnetic field

    Hi everyone, It is about the quantization of the electromagnetic field. The expression of field E and B are defined with: -the annihilation a- and creation a+ operators, and the frequency ω. So my question is: how does these fields must be expressed if they where "static"? I mean, how the...
  49. W

    I Question about electromagnetic spectrum and solar cells

    Would it be possible to change all wavelenths to one frequency that would then be sent to a solar panel adapted for it, or once split could to be sent to cells that work in that range? In other words use all the light to produse electric power