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
Recent contents Top users
  1. S

    Work done by electromagnetic force

    Homework Statement 1.Calculate the work done by the force F=i cos(pix/4) + j y2 along the path y=x2 in the x-y plane from (0,0) to (2,4). 2.Is the force F conservative? Explain. Homework Equations Work = Integration between a and b of F.dl The Attempt at a Solution 1. I know...
  2. D

    How Data on electromagnetic waves are transmitted ?

    Hello every one . We know Radio waves carrying data When a radio device receives radio waves , It render the waves and we hear sound . Now my questions are : 1 - How data on electromagnetic waves are transmitted ? When a electromagnetic wave hit a atom it absorbed by the atom like this...
  3. Y

    Calculating the Ratio of Electromagnetic Wave Speeds in Vacuum and Materials

    Homework Statement Electric and magnetic fields in many materials can be analyzed using the same relationships as for fields in vacuum, only substituting relative values of the permittivity and the permeability, ε = κε0 and μ = κmμ0, for their vacuum values, where κ is the dielectric...
  4. K

    Intensity of an electromagnetic wave, given only rms value of magnetic field

    Homework Statement Hi, here is the problem I'm having trouble with: The rms value of the magnitude of the magnetic field in an electromagnetic wave is Brms = 0.137 T. The intensity of this wave is approximately... Homework Equations E = cB I = (ErmsBrms) / \mu0 The Attempt at a...
  5. A

    Electromagnetic Transmission

    Figure below shows a load made up of a 50 W resistance, a 15 nH inductance and a 22 pF capacitance connected in series. The load is terminated to a two-wire transmission line with characteristics impedance of 50 W. (i) Determine the load reflection coefficient at an operating frequency...
  6. I

    How does electromagnetic feild made?

    Homework Statement I am high school student and was wondering how does electromagnetic field become existing? I konw equations describing are equations of max, but i do not understand how does field exist? equations of max describe but not tell why? that is my questions. Homework...
  7. N

    Electromagnetic fields and empty space

    is it possible for electromagnetic field to exist without matter?
  8. R

    Movement of lone electron in a plane-wave electromagnetic field

    I would appreciate some help regarding the movement of an electron in a plane-wave linearly polarized electromagnetic field. Its simple enough question, but I am not sure what approach to take. Let's say the electron is at rest in our frame of reference and the plane wave is continuous...
  9. O

    Electromagnetic Attenuation Conceptual Question

    Hello, Why does electromagnetic wave intensity attenuate exponentially with depth from its incident intensity in an object? Why is the relationship exponential? I just need a nudge in the right direction or more if you are willing. Thank you for any help!
  10. P

    Why Electromagnetic Waves are Transverse

    why electromagnetic wave is transverse?
  11. A

    Detecting sub-hertz electromagnetic radiation

    Could someone point me in the right direction on how low frequency (< 3 Hz) electromagnetic radiation is detected? I tried googling it, but my searches didn't really work; perhaps I was using the wrong terms? Another thing: what is the lowest frequency that has been detected, and what limits...
  12. A

    Force of neodymium magnet inside an electromagnetic coil

    Hey guys, Im trying to design a electric gear shiftier for a motor bike. Basically I require about 200N of force to change gear with a 10mm throw (in both directions). I would like to use a tube neodymium magnet. (23mm diameter 25mm high with a 5mm hole throw the centre with a N48 grade) What I...
  13. A

    Force of neodymium magnet inside a electromagnetic coil

    Hey guys, Im trying to design a electric gear shiftier for a motor bike. Basically I require about 200N of force to change gear with a 10mm throw (in both directions). I would like to use a tube neodymium magnet. (23mm diameter 25mm high with a 5mm hole throw the centre with a N48 grade) What...
  14. J

    What are electromagnetic waves made of?

    Electromagnetic waves, aka light and such. What is it?. I know that it is a wave of energy, magnetic and electric forces traveling in wave forms but when struck turning into a particle. But what exactly are they made of? Is it just a pure wave of energy and nothing else to it? Do physicists...
  15. M

    Electromagnetic pickup/reluctor waveform

    I'm trying to design a pickup/reluctor that produces a specific waveform. I'm using an automotive ignition pickup and expermenting with different shapes of reluctor but the results I'm getting aren't making any sense. The pickup/reluctor are of the familiar design with a pickup coil wound...
  16. A

    What Happens when a Bar Magnet Approaches a Conducting Loop?

    Fig.35 shows a light and flexible conducting loop X freely hung on a smooth horizontal rail. A bar magnet PQ approaches the loop from the right. Which one of the following descriptions about this process is correct? A If P is a N-pole, the loop will be repelled to the left and its area...
  17. A

    Electromagnetic wave from an antenna

    Homework Statement An electromagnetic wave from a wire antenna travels (from the reader) toward the plane of the paper. At time t = 0.0 s it strikes the paper at normal incidence. At point O and t = 0.0 s, the magnetic field vector has its maximum value, 5.01E-8 T, pointing in the negative...
  18. M

    Can an Electromagnetic Pulse Engine Revolutionize the Automotive Industry?

    This is my first posting with the forum and I hope I have chosen the appropriate topic. I am a 25 year automotive technician and have been pursuing an alternative application for the automotive industry. It is the electromagnetic pulse engine, which basically utilizes a regular 4 cylinder...
  19. D

    Less harmful electromagnetic waves

    Hi guys, I am too old to remember basic knowledge about electromagnetic waves :D I am looking for a combination of an electromagnetic wave and a material such that the wave can pass through human tissues, but it is blocked by the material. All I know is that X-ray/gamma can penetrate human...
  20. C

    A question about energy carried by a electromagnetic wave

    My teacher told us energy at a point of a progressive wave is proportional to square of amplitude, it is true for both mechanical and electromagnetic wave. But in the other lesson, he also tols us the energy of the EM wave is equal to hv, where h = Planck constant, v = frequency of the wave...
  21. L

    Electromagnetic wave, energy and universe

    All electromagnetic waves carry energy. We kno that most of the electromagnetic radiation escapes the boundary of the "physical(corporeal) Universe". Therefore, much of the energy is radiating out to the voids spreading beyond material universe. Thus, a great amount of energy is lost...
  22. I

    What blocks electromagnetic waves in the double-slit experiment?

    In the double slit experiment, a wave is forced to go through a tiny slit. I do not understand what is stopping it from going through the barrier. After all, we can think of an electromagnetic wave as just the electric/magnetic fields of a sinusoidally oscillating particle, evaluated using...
  23. W

    Electromagnetic Brake system

    Homework Statement Design and Perform calculation for an Electromagnetic Brake system of a truck having 3 Axils assuming that each axil carries equal load. The truck is carrying a load of 30000 Kg and the weight of truck is 6000 Kg and moving with 100km/h speed before the brake is applied...
  24. S

    Electromagnetic forces, finding alpha.

    Homework Statement When a third charge is placed at the origin, it is found that the force on it is zero. Find alpha? Two charges Q and 5Q are located as shown in the figure below. https://chip.physics.purdue.edu/protected/GiordanoEMimg/chapter17/17prob16.jpg If possible, please...
  25. W

    Electromagnetic Brake System

    Hello friend. I am working of design of Electromagnetic Disc Brake system. I have performed some calculation. which you can find on following links. https://rapidshare.com/files/3568781938/untitled_folder.zip https://rapidshare.com/files/2134776724/untitled_folder_2.zip Please have a...
  26. P

    Electromagnetic repulsion query

    Hello, I have been playing around, making my own electromagnets. As I am out of my depth, I am experimenting with 1.5 to 9 Volt battery packs. I am hoping to have a setup where two electromagnets, around the size of a AA battery placed about an inch apart can noticibly repell each other a...
  27. K

    Electromagnetic Radiation and Magnetic Waves

    Hi, First post on these forums, but I've lurked a bit in the past. I'm doing a project on the Faraday Cage, and I have a quick question... I was wondering why a Faraday Cage can block electromagnetic radiation like a radio wave (which, as far as I can tell, is a "mix" of a magnetic field...
  28. H

    Electromagnetic damping

    I will appreciate any contribtion to the question below. > You have a system that consists of a coil and magnet. The magnet, which is resting on a spring, is free to move up and down in the coil. This system can be modeled as a simple mass-spring-damper system with a...
  29. C

    Electromagnetic mass vs its velocity

    Dear friends, I have a 5 minute presentation to give on the dependence of electromagnetic mass on its velocity for my physics class. This could be a very broad question to answer, but all I ask is to direct me to some useful links. I have troubles with that because I keep finding regular...
  30. H

    Electromagnetic energy injected into combustion process?

    Hmm, not sure if this is the right place to be asking this. I am wanting to understand what effects electromagnetic energy can have when injected into the combustion process of hydrogen and oxygen? Can anyone tell me or point me what effects can occur or point me in the right direction to...
  31. D

    Which way is the electromagnetic field moving?

    Hi all I am wondering as this diagram shows. Which way is the electromagnetic field(s) moving? http://www.biophotonicsresearchinstitute.com/Picture1.png Thanks.
  32. S

    Electromagnetic buzzer project help

    hi, i have to build an dc electromagnetic buzzer for school project, but I'm having tons of trouble! can anyone offer advice to help me out? (like good websites with instructions or pointers?) i have most trouble with the connect/disconnect part of the buzzer! i have this nail that is fixed in...
  33. N

    Additional Term added to Electromagnetic Lagrangian

    I am currently reading and trying to solve most of the problems in Carroll's Geometry and Spacetime. I am generally okay at the math (I've done some mathy Riemannian Geometry type stuff), but am not overly good at some of the higher-level physics. Homework Statement (Chapter 1, Question 13)...
  34. M

    Inducing a current through moving charges or electromagnetic radiation

    I have recently found a circuit schematic that can pick up radio signals without the need of a battery. Is this an example of electromagnetic induction? If so, how much voltage/current is induced? Does it change the properties of the electromagnetic wave, e.g. energy, wavelength, etc...
  35. T

    Inductor and electromagnetic field with voltage

    I'm having hard time understanding how exactly current that passes through inductor transforms energy into magnetic field and then into voltage, with 90° phase shift. I drew schemes representing sinusoidal imput current, its magnetic field and voltage relation. Is it correct? Would...
  36. Mueiz

    Electromagnetic Interference in Einestien Field Equation

    According to EM theory,in the absence of any interaction with matter, destructive interference in one location will always be balanced by constructive interference in another location keeping the law of conservation which means that there is no local conservation law for energy flux regarding...
  37. T

    Determine the Energy of Electromagnetic Radiation After Particle Collision

    Homework Statement The positron and the electron each have a rest mass of 9.11 x 10-31 kg. In a certain experiment, an electron and a positron collide and vanish, leaving only electromagnetic radiation after the interaction. Each particle is moving at a speed of 0.20c relative to the laboratory...
  38. R

    Explaining Electromagnetic Forces: Repulsion & Attraction

    What is the mechanism for explaining the different effect of repulsion and also attraction due to the exchange of virtual photons in the electromagnetic forces? For example, the electrostatic force between two point charges, for both when they are oppositely charged and like charged?
  39. N

    How much energy can a solar panel collect in one hour?

    Homework Statement The average intensity of sunlight at the top of the Earth's atmosphere is about 1400 W/m^2. What is the maximum energy that a 20 m × 30 m solar panel could collect in one hour in this sunlight? Homework Equations Not sure what equation to use The Attempt...
  40. S

    Electromagnetic waves and charge sources

    Hi PF Are there an interaction between an electromagnetic wave and a charge source? For example, does an electromagnetic wave get attracted by a charge source, the same way the Earth attracts the moon? Or is something else going on?
  41. E

    Electromagnetic Reflection and Refraction

    Homework Statement An EM wave travels in vacuum and incidents on a dialectric material in the XZ plane. The wave's polarization is in the \hat{y} direction. Prove that the polarization of both reflected and refracted waves are too along the \hat{y} axis. Homework Equations The...
  42. E

    Details on electromagnetic waves?

    i really want to understand the lesson so bad i read the lesson 10 times and the lesson is like 50 pages and i still don't get the concept of how electromagnetic waves were originated?? and what about polarization? please with all the details you have and thank you
  43. J

    Radiation pressure and electromagnetic waves

    Homework Statement A laser beam of power P and diameter D is directed upward at one circular face (of diameter d < D) of a perfectly reflecting cylinder. The cylinder is levitated because the upward radiation force matches the downward gravitational force. If the cylinder's density is ρ...
  44. Y

    Getting lorentz electromagnetic force from hamilton principle

    the title is pretty clear, so we have this F=q( E+V/c X B) the force for a point charge q in an electromagnetic field. and we have the formula to the hamiltonian of electromag force: H= (P+ q/c.A)/2m _ e\phi. the question is how can I get the F from the hamilton principle, using the...
  45. P

    Photon gas as medium for electromagnetic propagation

    Hi Guys, I came across this article by Jikang Chen and it is of importance to me to know what measure of credibility this concept holds in the general physics fraternity. I do not have the background to make sense of the mathemetics or physics cited. I would appreciate your comments. The...
  46. K

    Electromagnetic Radiation and Mediums

    Homework Statement Hello there! I have a couple of questions regarding light(EMR) and how it behaves when moving from one medium to another. From what I understand, the frequency of any light wave, when it moves from one medium to another, stays the same. As a consequence of this, the velocity...
  47. W

    Electromagnetic radiation prevalence

    Hello, Perhaps my wording is a bit off so excuse me for that. I think it best to explain by way of a thought experiment. Say there is a device that counts the amount of photons with the same wavelength for all possible wavelengths. What is then the intensity vs. wavelength curve that I would...
  48. G

    What is Electromagnetic Induction and How Does it Work?

    Hi everyone, So I feel sort of stupid posting what you'll probably find is a very elementary question but physics really isn't my best subject and I'm completely stumped. Thanks so much! Oh, and there's also the possibility that this question is just really badly worded. Homework Statement...
  49. S

    Exploring the Meaning of q(t) in Electromagnetic Waves

    Hi, In electromagnetic wave, electric field take the form E(z,t)=A q(t) sin(kz) where A is a constant, k is a wave number, and q(t) is a time dependent factor having the dimension of length. This mean that q is a position..but position of what ?? Is a position of the wave ?
  50. P

    Does a Falling Wire Near a Magnet Experience a Magnetic Force?

    Suppose a single wire (in a horizontal position) falls toward a pole of a magnet. Does the wire slow down? A diagram is attached.
Back
Top