Electromagnetic force Definition and 78 Threads

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.

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  1. S

    I Can a cloud of electrons be stabilized by interactions between them?

    If you have many free electrons forming a cloud they wouldn't last too much as they would be repelled from each other due to electromagnetic forces. Gravity wouldn't help since it is much weaker than electromagnetic force, so electrons would still fly away However, can they be stabililized by...
  2. S

    I Gravitational analog of electromagnetic force

    Is there a gravitational analog of electromagnetic force? [Apart from the obvious "static" forces, ie electrostatic between fixed charges and gravitational between fixed masses.] I am thinking of the classic situation of a moving charge (or current) creating a magnetic field which then...
  3. 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...
  4. Woomir

    I Why is my magnetic levitation experiment not working?

    [Mentor Note -- Two similar thread starts merged into one] Hey all, I have been working on this project for a while now, which features suspending an object midair through the use of magnetic levitation principles. Cool right? And so I have been researching and trying, even finding ground...
  5. 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?
  6. N

    B Electromagnetic force of Electrons

    If you could command all the electrons in an average human body and get them to spin in synchronicity (a clockwise circle in the horizontal plane) how much magnetic force does that produce? Would it create a force against gravity and make you feel lighter? How much lighter?
  7. R

    How to find electromagnetic force between nucleus and electron?

    Hello, I'm new here and honestly I'm not a physics student. I'm studying engineering and so, understand little of physics. I am trying to find the bond force of graphene's free electron. That means, the electromagnetic force by which the electron is bound to the nucleus. I can only calculate it...
  8. Amoghgirgaonkar

    The Mystery of Purple Objects: Understanding Electromagnetic Force

    ans is opt4
  9. MacGyver Megh

    B The electromagnetic force of quarks

    If an up quark has 2/3 of positive charge and down quark has 1/3 of negative charge then why don't they add together by their electromagnetic force?
  10. B

    A How does the electromagnetic force influence a galaxy (if at all)?

    Like what are the chances that dark matter can be described with electromagnetism instead?
  11. B

    Please explain "Electromagnetic force is mediated by light"

    We have talked about light behaving as a wave and a particle. Having trouble understanding what 'mediated' means in this context.
  12. M

    How close does an electron get to a proton to be attracted

    I couldn't fit the whole question, it should say "How close does an electron have to get to a proton to be attracted to it" And I know it can depend on the speed and direction they are traveling. Can we just pretend they are stationary for this answer please. By attracted I mean the electron...
  13. gibberingmouther

    Line Integral for Electromagnetic Force

    http://web.mit.edu/sahughes/www/8.022/lec01.pdf So I'm trying to understand how to get from F = ∫[(Q*λ)*dL*r]/(r^2) to F=∫q*λ*[(xx+ay)/(a^2+x^2)^(3/2)]*dx Like I don't understand why the x and y components of r are negative, or why "The horizontal r component is obviously zero: for every...
  14. C

    Monitor restarts when I make an electric arc

    Why does my laptop's screen refresh every time I bring a metal object (any size) to my electric lighter? -Happens when I am 1 foot away from the laptop -1 foot away from the external monitor's wires (HDMI & power) 1. Video footage (MUST WATCH) NOTE: the laptop screen also flickers a bit NOTE...
  15. F

    Electromagnetic force on particles forming a square

    Homework Statement [/B] (a) At each corner of a square is a particle with charge q. Fixed at the center of the square is a point charge of opposite sign, of magnitude Q. What value must Q have to make the total force on each of the four particles zero? (b) With Q taking on the value you just...
  16. P

    Find the magnitude of the electromagnetic force on electron?

    Homework Statement In a certain region of space, there is a uniform electric field, E = 4.28 x 104 V/m directed due east, and a uniform magnetic field B = 0.071 T, also directed due east. What is the magnitude of the electromagnetic force on an electron moving due south with a velocity of 3.09...
  17. C

    Amount of excess charge to overcome Earth's gravity

    Years ago I read an article illustrating the vastly different strengths of the electromagnetic and gravitational forces. The article gave a figure for the number of excess electrons dispersed throughout the Earth that it would require to overcome the gravitational binding of Earth's matter and...
  18. mertcan

    How Is the Red Part of Stratton's Equation Derived from Light Pressure?

    Hi everyone, initially I would like to put into words that this equation in my attachment is provided by Julius Adams Stratton but he do not derive the equation. The only part I do not understand and can not derive is the "RED" part. He just says it results from light pressure. So, I would like...
  19. Incnis Mrsi

    A Chirality of the electromagnetic force on atomic matter

    It’s commonly held that left and right photons interact with matter in exactly the same way, because electromagnetism “conserves parity”. But we know that P-symmetry, in our world, is generally broken. Even according to the Standard Model, when light propagates through some media, it interacts...
  20. T

    Stopping the Slowdown: Electricity & Electromagnetic Force

    Electricity flowing through a wire creates it's own magnetic field. So when the electricity is flowing through a wire, it's magnetic field works AGAINST the generator, slowing it down. So is there is any way to stop slowing down process without increasing amount of current ??
  21. facenian

    How Does a Rotating Disk Generate Torque in a Magnetic Field?

    Homework Statement A circular disk rotates about its axis with angular velocity ##\omega##. The disk is made of metal with conductivity g, and its thickness is t. The rotating disk is placed between the pole' faces of a magnet which produces a uniform magnetic field B over a small square area...
  22. tzukishiro

    I Why is the weak force 10^-7 times the electromagnetic force?

    In the case of two protons in the nucleus. I've seen charts with that info, but I don't know how... How can I calculate that ratio? I've looked everywhere, and I can't find anything... Thanks
  23. Einstein's Cat

    Electromagnetic Force in Newtons

    I may be asking a ridiculous question and if so, then I apologise. Anyway, if there is an object with a charge of +1 and also another object with a charge of -1, one metre away from the first object, then what is the force between these objects in Newtons? Also is there a way in which to convert...
  24. Einstein's Cat

    Is there a unit for measuring electromagnetic force and what symbol denotes it?

    In the same sense that Newtons (N) are the unit for measuring gravitational force, is there a unit for measuring electromagnetic force and if so what is it and what symbol denotes it? Thank you for your help and time!
  25. N

    Calculating Spring Constant and Forces in an Electromagnetic System

    Homework Statement We take a horizontal copper bar with length of 20cm and attach it from the middle to a vertical spring which mass is neglected and has a spring constant K, we apply a horizontal magnetic field with magnitude 1/2 T and have a 10A current run in the copper bar. The bar rests...
  26. N

    Electromagnetic force increasing/decreasing

    The electromagnetic force F = I*L*B * SinΘ will increase based on the value on SinΘ.What's the physical explanation for this? Why does the angle between vectors B and IL matter?
  27. P

    How Does QED Explain the Electromagnetic Force

    From a conceptual point of view, how is it that Quantum Electrodynamics explains the interaction between two charged particles, (let's say two electrons)? I've heard people say that the electrons exchange photons, but how is it that an electron would know when to send off a photon and that it...
  28. U

    Cross Section for e+e- in EM interaction - Is it the same?

    I was studying my notes and specifically for the ##e^+e^- \rightarrow \mu^+ \mu^-## process, cross section is given by \sigma = \frac{4\pi}{3} \left( \frac{\alpha \hbar c}{W} \right)^2 where ##\alpha = \frac{g_{EM}^2}{4\pi}## and ##W## is the centre of mass energy. Is this the same for...
  29. L

    Experimenting with Electric Force on a Van Der Graff Generator

    How to carry out an experiment to find range of electric force on a van der graff generator?Thanks!
  30. A

    What were the clues that the weak and EM force are the same

    Hello, I've been reading a book on particle physics for the general audience, and as you might expect, I was left with a slew of nagging unanswered questions. There was a chapter on gauge symmetry where the author described that the weak and the EM forces are the same force at some energy...
  31. M

    Understand Electromagnetic Force in Different Inertial Frames

    I've attached an image to a conceptual problem I'm having a little trouble understanding. It shows part a, b, c, and d (but d is cut off). a and b are one inertial frame while c and d are another. c and d makes sense, but I'm having a little trouble with a and b. Based on the image for c, there...
  32. T

    About the photon exchange and the electromagnetic force

    As many of you know better than me, photons are the carriers of the electromagnetic force, so they exchange is necessary for example in order to keep an electron around a proton in a hydrogen atom. So how does this work exactly? What is this “exchange”? In the mentioned system, which one of the...
  33. R

    Exploring the Charge-less Boson of the Electromagnetic Force

    Why is it that the boson for the electromagnetic force does not have a charge? I apologize if this question is rudimentary, as all of you guys are WAY out of my league. Thanks!
  34. C

    Origins of the electromagnetic force

    I saw a very old post where someone asked where an electron gets it's charge. Where does the charge come from? Doesn't it arise from the interaction with photons? My understanding is that electric charge and magnetism can not exist without photons, and the electron itself most likely could not...
  35. O

    Calculating Electromagnetic Force at 0 Distance?

    If you'll allow me to disregard the effects of Strong Interaction, how would I calculate the Electromagnetic Force between two oppositely charged point particles that are in contact with one another? Let's assume two particles with opposite Elementary Charges: 1.60218E-19 and -1.60218E-19 and...
  36. D

    Electromagnetic force between Parallel Currents

    Hi, sorry if this has been asked before. It is known that two parallel wires carrying electric currents in the same direction attract one another. The force is known as electromagnetic force. My question is whether this has been checked for two pure currents of charges. Specifically, whether...
  37. F

    Calculating Electromagnetic Force on a Moving Wire

    Homework Statement A wire of length L=20cm travels with an acceleration a=0.002m/s2 perpendicular to the Earth's magnetic field (B=20μT). Considering that the wire starts from rest, calculate the value of the emf (electromagnetic force) when an hour has gone by. Homework Equations My...
  38. S

    Can Parallel Charged Particles Maintain Their Speed in Space?

    Homework Statement when two like charged particles are traveling in space on parallel tracks, exert electric and magnetic forces on each other, then what is their speed when they continue to move in the parallel track? Homework Equations since both are lick charges there should be a...
  39. Q

    Feynman Diagram for Electron-Proton Attraction

    Would it just be the same as with two electrons? (or any other pair of particles with the same charge) I'm kinda in two minds, I suspect that is wrong because wouldn't the fact that they attract each other (instead of repelling) means that the diagram would be drawn differently?
  40. H

    Calculate electromagnetic force on iron object

    Hello, I need to calculate/estimate the force between a solenoid electromagnet and a piece of iron on a certain distance from the magnets airgap, preferable in a simple way under ideal conditions rather than a very exact calculation. I have found the following formula at a couple of places...
  41. umair20

    How friction is an electromagnetic force?

    how friction is an electromagnetic force?
  42. C

    Help With Electromagnet and Air Cores

    hello i need some help, i know very little about EM. i would greatly appreciate any advise u can lend me. i need to make an electromagnet but i am wondering how strong air cores can be? will an air core be able to work on and off continuously for hours at a very high rate of speed, it...
  43. J

    How do we know gravity is not just a large scaled electromagnetic force?

    I mean, you can only start to see the effects of gravity when a large amount of matter is in one place. What if all the electric or magnetic fields in every single atom of that planet or star or black hole, ect... combine into one large field, big enough to create what we know as gravity?
  44. A

    How photon is force carrier of electromagnetic force in macroscopic level.?

    i have gone through that photon is force carrier of em force..but in macroscopic level as far as I studied I know em force is designated with field in macroscopic rather than a particle like interaction.so how can they justify that em force is managed by photon.If photon is more plausible is it...
  45. D

    Is this a valid equation for determining electromagnetic force?

    I have been searching the internet for a simplistic equation which is capable of calculating the force of an electromagnet. I think I have found one at http://www.ehow.com/how_5969962_calculate-force-electromagnet.html however am not entirely sure this is a correct equation (don't really trust...
  46. C

    Comparison of strong nuclear force and electromagnetic force

    How much stronger is the strong nuclear force compared it to the electromagnetic force beyond what could be accounted for by the inverse of the distance squared?
  47. B

    Electromagnetic force required to levitate an object

    I'm trying to use some home-made electromagnets to lift a small object. I am a college student, but this is a personal project, so while I may reference something from a textbook, its not a homework problem. I know that I can get some iron bar, coil it with wire, run some current through it...
  48. P

    How Does Mass Affect Electromagnetic Attraction and Repulsion?

    First: Since photons carry electromagnetic force between charged particles, and the gravitational force is presumably separate (at least at typical energy levels) then is it correct that an object's mass is irrelevant in considering electronic(electromagnetic) attraction/repulsion? i.e. an...
  49. B

    Electromagnetic force and some trig

    Homework Statement The diagram below shows two pith balls, equally charged and each with a mass of 1.5 g. While one ball is suspended by a thread, the other is brought close to it and a state of equi- librium is reached. In that situation, the two balls are separated by 2.6 cm and the thread...
  50. M

    Which is an example of the electromagnetic force?

    This was a question on an online homework for a modern physics class. I had two chances to answer it, but I was wrong both times, so I'm simply curious what the answer is. Homework Statement The Attempt at a Solution (a) Quarks attracted to one another is the strong force (b) A...
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