What is Electrodynamics: Definition and 416 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.

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  1. N

    Electrodynamics: Solve the differential equation

    Homework Statement Hi all. Please take a look at the attached circuit, where the current is direct (i.e. DC). I have found the following differential equation using Kirchoff's laws: V=\frac{R_1+R_2}{R_2C}Q+R_1\frac{dQ}{dt}. I wish to solve this equation, and thus to find Q(t).The Attempt...
  2. N

    Electrodynamics: An R-C circuit with DC

    Homework Statement Hi all. I am looking at a R-C circuit (in series) with DC. I am just trying to analyze what happens at the instant the switch is turned on. If we set up Kirchoff's second law for this system, we can see that the current will not be constant, and this is because the...
  3. C

    Classical electrodynamics -Good conductor

    Homework Statement The question given is an electromagnetic wave incident on a vacuum metal interface. The wave is incident normally. We're given that the metal is a good conductor i.e. \omega \tau <<1 where \tau is the collision time of the metal and omega is the angular frequency. The metal...
  4. C

    Griffiths Electrodynamics book: Electric potential

    Homework Statement This is from Prob. 2.25 Two point charges with separation d, P is a point at a distance z above the mid-point of the charges. The last sentence asked if one of the positive charges is changed to a negative one, what is the potential at P? What field does it suggest? Explain...
  5. T

    Electrodynamics in differential forms

    (Ok, post edited. It should be ready for reading.) I'm attending an electrodynamics course and the notation is in differential forms. The course material, however, is not yet finished so it's very coarse. We're supposed to have an introduction to differential forms as the course proceeds, but...
  6. G

    Ive been reading ON THE ELECTRODYNAMICS

    Hi guys, I came across On the Electrodynamics of Moving Bodies while searching the net on relativity. I started reading it cause I thought It would be quite fun to do, not hoping to understand allot of it. I understand the basic (no-mathematical) concepts behind relativity, but I would like to...
  7. M

    Classical electrodynamics

    On the Z=0 plane the charge distribution is of the form \rhos=\rho0 sin( \alpha x )sin( \beta y ) find the potential everywhere, assuming that \phi(z\rightarrow±\infty)=0 according to the answer, we should look for a potential of the form A sin( \alpha x )sin( \beta y )f(z) (due to the...
  8. M

    Classical electrodynamics - Green function

    Hello, I don't fully understand the meaning of Green function, and how one should use it. According to Jackson's "Classical Electrodynamics" - 'the method of images is a physical equivalent of the determination of the appropriate F(x, x') to satisfy the boundary conditions'. Where Green...
  9. C

    Electrodynamics vs. Electromagnetism: On the use of either term

    I am curious to hear people's opinions and to run a poll on the use of the term electrodynamics vs. the term electromagnetism. Which do you prefer; why? Are there instances where you would use one over the other? Etc? To start off: Some like the use of electromagnetism when speaking of the...
  10. gulfcoastfella

    Self-Study Electrodynamics: Home Lab Experiments & References

    I'm engaged in self-study with advanced undergraduate-level physics, currently focusing on Griffith's Electrodynamics text. I'm enjoying the problem sets in the text, but I sure would love to do some lab-work here at home. Does anyone know any good references for E&M labs or experiments?
  11. Peeter

    Inhomogenous electrodynamics wave equation

    I was playing around with some manipulations of maxwell's equations and seeing if I could work out the wave equation for light. I get: (\nabla^2 -{\partial_{ct}}^2) \mathbf{B} = -\mu_0 \nabla \times \mathbf{J} (\nabla^2 -{\partial_{ct}}^2) \mathbf{E} = \nabla \rho/\epsilon_0 + \mu_0...
  12. G

    Electrodynamics in particle physics

    Hi: I've heard that in electromagnetism, there is a system of units called Lorentz - Heaviside system, and that in particle physics, tis system is used insted of the gaussian or the SI. Why do particle physicist use this system? and by the way, How do we go from the Gaussian...
  13. C

    ON THE ELECTRODYNAMICS OF MOVING BODIES by A.EINSTEIN

    We all know this book... its is basically the SR as we know it. you can find it here ww.fourmilab.ch/etexts/einstein/specrel/www what i was looking for was how and on what basis back on 1905 the Albert figures out the speed of light is constant... all I get is this "Any ray of light...
  14. N

    Conceptual questions on electrodynamics

    Hi guys I have some questions about electrostatics, and I hope you can help me. Here they are: 1) Please take a look at the following example...
  15. N

    Electrodynamics and electrical fields

    [SOLVED] Electrodynamics and electrical fields The question is: A long cylinder carries a charge density that is proportional to the distance from the axis ρ =kr, where k is a constant, r is the distance from the axis. Find electric field inside the cylinder. My attempt: Ok, first of all...
  16. haushofer

    Can the Noether current be derived from the electrodynamic Lagrangian?

    Hi, I have a computational question which concerns forms. I want to compute the variation of the electrodynamic Lagrangian, seen here as an n-form: L = -\frac{1}{2}F \wedge *F with F=dA. I want to derive the Noether-current from this Lagrangian. The symmetrytransformation we are concerned...
  17. N

    Calculating Potential and Electric Field Between Concentric Spherical Shells

    Consider two concentric spherical shells of radii R1 and R2 (R2>R1 ) which are maintained at potentials V1 and V2. Find the potential and the electric field in the region between the two shells, and show that the charge on the inner shell is given by q1= -4 pi...
  18. B

    Use of potentials (electrodynamics, classical)

    hello, I've just gone through a derivation using the vector potential A, and using the equation derived (a wave equation) which arises from using the lorentz gauge, it is applied to the problem of a current sheet in the xy plane, located at z=0 with current in the x direction only. the current...
  19. W

    Electrodynamics problem: charge origin?

    [SOLVED] Electrodynamics problem: charge origin? When you have an insulating region within a conductor and an electric field is applied such that a current flows, this current will be made to move around the insulating region. -I assume a charge distribution will arise on the surface of the...
  20. C

    Recommendations for graduate text on electrodynamics

    can anyone tell me whether jackson's or landau and lif****z's E&M book is better for self study (basically which is better for learning the theory and doing the problems also) assuming all prerequisite knowledge and material has been met (such as griffiths E&M text).
  21. B

    Ferromagnetism, electrodynamics and field theory

    Hi all, I'm a bit confused about ferromagnetism (and I've come to realize that I'm not the only one)! I'm currently studying electrodynamics and field theory in general to solidify my understanding of such, but permanent magnets and ferromagnetic materials seem to be often ignored in the...
  22. P

    Fluid dynamics vs Electrodynamics

    If you could only do one which one would you choose? And why?
  23. michael879

    Conflict between electrodynamics and classical relativity?

    Id just like to start by saying I believe relativity is 100% at least in macroscopic terms. However, I'm having trouble seeing what the conflict was between electrodynamics and relativity. Electrodynamics in a nutshell states that light goes a constant c. relativity states that physical...
  24. P

    Did Weber's Electrodynamics Challenge Traditional Physics Theories?

    [Note: my first post attempt gave me an error message, so I think it didn't go through as I don't see it showing up in the forum; apologies if this ends up duplicate and in that event please delete one copy.] The site I found this on is pretty crackpot, but I'm interested in debunking this...
  25. C

    Classical electrodynamics problem

    Homework Statement Hi to everyone! I would like you to help me for a problem of classical electrodynamics. I have to study the relativistic motion of a charged particle in a coulombian field with center in the origin of the cartesian axes. I have to study the case in which the initial...
  26. A

    Jackson Electrodynamics problem 9.8a

    Homework Statement 9.8a) Show that a classical oscillating eletric dipole p with fields given by (9.18) radiates electromagnetic angular momentum to infinity at the rate \frac{d\mathbf{L}}{dt}=\frac{k^3}{12\pi\epsilon_0}\textrm{Im}[\mathbf{p^*\times p}] Hint: The electromagnetic angular...
  27. Z

    Is Jackson's Classical Electrodynamics a Good Resource for Self-Study?

    The short version:I'm taking Classical electrodynamics this semester, I found out that I have this book: Classical Electrodynamics by J.D.Jackson Anyone know this book?Would it be a good choice to help me study?
  28. A

    Jackson Electrodynamics problem 6.5b

    Homework Statement A localized electric charge distribution produces an electrostatic field, {\bf E}=-\nabla \phi Into this field is placed a small localized time-independent current density J(x) which generates a magnetic field H. a) show that the momentum of these electromagnetic...
  29. R

    Chapter 7 of Jackson's Classical Electrodynamics

    Chapter 7 of Jackson's Classical Electrodynamics Well I've been up for a few hours, and here I am at night, midway through swimming the brisk cold English channel that is chapter 7 of Jackson's Classical Electrodynamics (my first problem set is due Wednesday - six problems), and... well, just...
  30. B

    Relativistic electrodynamics

    If someone could help me with this one that would be great. My prof has not been in his office in quite some time... -A wire of cross-sectional area A carries a current I, and has zero net electric charge in frame O. (a) Find the magnetic field a distance r from the axis of the wire (b)...
  31. N

    Help with Electrodynamics Equations

    Could anybody help me solve this equations ( I'm sorry for my english) m\frac{d^{2}{x}}{dt^{2}}=qB\frac{{dy}}{{dt}} m\frac{d^{2}{y}}{dt^{2}}=qEy-qB\frac{{dx}}{{dt}} m\frac{d^{2}{z}}{dt^{2}}=qEz X(0)=Y(0)=Z(0)=0 \frac{dx}{dt}(0)=Vx \frac{dy}{dt}(0)=0...
  32. J

    Books recommendation on electrodynamics

    I just finished Griffths intro. to electrodynamics and works half of the problems Griffths provided. Now,I attempt to read Jackson's electrodynamics and found it is very hard for me... Indeed, should I need to go back to Griffths's electrodynamics and learn those concepts again? or I should try...
  33. L

    Jackson Electrodynamics Problem 2.3

    The problem and a solution can both be found here. In this problem there is a line charge and two conducting planes at the axis. You use the method of images to solve it. The first three parts are easy enough. The fourth asks what the electric field is far from the origin. I do not know...
  34. L

    What math background do I need before delving into Jackson Electrodynamics?

    I am interested in attempting to work through Jackson over the summer and I am wondering what mathematics backround is necessary before doing this. I have ken calc 1-3, DE, complex analysis (for engineers), and a probability and statistics course. Surprisingly, I have never taken a linear...
  35. S

    An easy electrodynamics question, and yet

    My first homework assignment for griffiths is underway. Here is a problem I can't figure out. Q. Two identical conducting small spheres are placed with their centers 0.350 meters apart. One is given a charge of 12.0 nC and the other is given a charge of 16.0 nC The spheres are...
  36. J

    General Relativity + Electrodynamics #2

    Some of the comparisons between gravity (in the weak field limit) and electromagnetism were really interesting (https://www.physicsforums.com/showthread.php?t=80710 ). Unfortunately, that got locked due to someone presenting their pet theory. The topic seems too good to end, so let's hope we...
  37. J

    General Relativity + Electrodynamics

    GR and EM are classical field theories, but later in the questions I wish to treat this in a semiclassical manner. For those helping to answer, please be specific which answers can be done in a purely classical manner, and which require quantum approaches (and please let me know if the...
  38. Y

    Electrodynamics homework question

    Hello I have a question I got which I've been sitting on for weeks.:grumpy: I have an electron going through a conducting infinite cylinder of R radius. I need to know what the induced charge is on the cylinder, and the potential, for different speeds of the electron. a) for slow speed v<<c...
  39. maverick280857

    Prerequisites for Quantum Electrodynamics

    Although this is usually a graduate course, I want to know what all the preqrequisites for studying it seriously are. (I've been reading Feynman, Schweber and a bit of Griffiths which pumped my interest). I think mathematics should be calculus, group theory and all the stuff needed for QM. As...
  40. T

    Need 4d electrodynamics Book Names

    Any one can guide me to some good books about 4-dimentional electrodynamics? I don't want books that starts from electromagnetical theorems for maxwell, i want them to start from 4-dimentional systems and operations on them or tensors about them Thanks,,
  41. A

    Understanding Electrodynamics: P.294-296 of Griffiths 2nd Edition

    This is a question regarding electrodynamics. Specifically I am reffering to p.294-296 of Griffiths 2rd edition. If you have the book it will be easier to see what my question is if you see the picture. There a loop with a resistor on the right end, part of the left side of the loop is in a...
  42. G

    Derieving relativistic electrodynamics equations

    I'm trying to derive the Lorentz-invariant field equations, using a point charge (well, a positron actually) centered in the coordinate system. I'm trying to find the electric & magnetic fields generated by it. I've tried using Dirac delta functionfor the charge density. S' frame of reference...
  43. V

    The meaning of curl in Electrodynamics

    Hi I have a hard time understanding what the curl really means in Maxwell's equations, for example in a steady-state you have \nabla\times \textbf{E} = 0 and in a time-varying field you have \nabla\times \textbf{E} = -\frac{\partial \textbf{B}}{\partial t} The meaning of the...
  44. L

    Jackson's Classical Electrodynamics

    Find out if it's your friend or foe when you're using this book. http://textbookreview.blogspot.com/
  45. A

    Quantum Electrodynamics: A Basic Textbook for Self-Study in Undergrad Years

    What is a good textbook that gives a basic understanding of quantum electrodynamics? My university doesn't have any courses in this subject so I am going to have to teach to myself. What do I need to know and understand before I dig down into quantum electrodynamics? So far I am at my...
  46. A

    How can electrodynamics prove the stability of electron

    in quantumdynamics, the stability of electron of H atom is a hypothesis. but if electrodynamics is right in quantum theories, electron circling a H atom will emit energy, then how can electroquantum theory give a sound prove of the stability of electron? thanks.
  47. H

    Mirror Image Problems in Electrodynamics

    What do the mirror image problems in electrodynamics exactly focus at? Are they only based on the uniquesness theorem ,which we study in Differential equations.!But i find their application to be limited since they can be applied to a surface which is grounded.! One more thing ,how does it...
  48. A

    Help on Introduction to Electrodynamics 3rd edition by David J. Griffiths

    Help on "Introduction to Electrodynamics 3rd edition by David J. Griffiths" I'm studying that book right now, but I'm having a hard time understanding... Can someone explain what a dirac delta function is and how to use it? I also don't understand the what is the electrostatic boundary...
  49. B

    Help Electrodynamics - Find Solutions to Griffiths Problems

    help electrodynamics... dear friends i want to know more whether there is any book that gives solutions to griffiths electrodynamics problems :tongue2:
  50. H

    Electrodynamics: Understanding Bound Charges

    what is basically the concept of bound charges in electrodynamics??
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