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.

View More On Wikipedia.org
Recent contents Top users
  1. e2m2a

    Question about energy density in On the Electrodynamics of Moving Bodies

    In section 8 of Einstein's On the Electrodynamics of Moving Bodies Einstein uses the expression A(sq)/8 pi. He states this represents the energy of light per unit volume. Does anyone know how he derived this?
  2. AJ Bentley

    Source for relativistic electrodynamics

    Just reading Prof. Mead's book 'Collective Electrodynamics' Does anyone know of a (readable) discussion of electrodynamic momentum vs. total momentum with a relativistic correction for velocity?
  3. M

    A physical interpretation of classical electrodynamics

    I was wondering whether any members of this PF sub-forum would help me towards some physical interpretation of Maxwell’s time-dependent equations, which must ultimately underpin any classical description of EM wave propagation. I know that some might simply suggest reading a good textbook, but I...
  4. W

    Exploring Electrodynamics with Landau and Griffiths

    Since I'm reading SR/GR now, I thought I'd complement it with a treatment of EM also. I am looking for a treatment of electrodynamics at the level of Landau, i.e. I want the covariant formulation and the Lagrangian formulation of the fields. My background is the level of Griffiths. Landau seems...
  5. J

    Electrodynamics - relativistic generalization of a formula

    [PLAIN]http://img46.imageshack.us/img46/1699/dsfadsfas.png The formula holds in the rest frame. Why is this particular extension 'the' extension? (Context is Electrodynamics/SR. It's just a piddly 16 lecture course that outlines Electrodynamics and SR and a bit of Quantum phenomena at the end...
  6. N

    Book for electrodynamics and relativity

    Hi, I take a second course of electrodynamics, one of the main subjects is e.d and relativity, the lecturer use Jackson as the course's textbook. Is there any other book which covers this subject in the same level as Jackson which is more friendly and can be used for self-study (Jackson is...
  7. B

    Relativistic Electrodynamics

    Hey guys, I couldn't find a question like this elsewhere on the forum so hopefully I'm not repeating what someone has already asked. Can a purely electric field in one inertial frame of reference transform into a purely magnetic field in another? Explain -- My initial instinct was...
  8. L

    Calulate emf unsing electrodynamics

    Homework Statement There is a Static magnetic field,with its intensity B. Assume a coil moving in the magnetic field, with its position function y=asinwt. then calculate the voltage of U Homework Equations The Attempt at a Solution
  9. M

    Griffith's Electrodynamics 6.8

    Homework Statement A long cylinder of radius R carries a magnetization \vec{M}=Ks^{2}\hat{\phi} where k is a constant, s is the distance from the axis, and \hat{\phi} is the usual azimuthal unit vector. Find the magnetic field due to \vec{M} for points inside and outside the cylinder.Homework...
  10. V

    Relativity and Electrodynamics question

    1. Hi everyone, I'm a final year in university and have got a "Relativity and Electrodynamics" exam coming up. I'm going through past papers and can't seem to work out how to tackle this problem, any help would be much appreciated. Suppose in some inertial frame S a photon has 4-momentum...
  11. M

    Does it work this way (intro electrodynamics)?

    Homework Statement Have a permanently (uniformly not radially) polarized sphere surrounded by a charged conductor How is the charge on the conductor distributed (the added charge)? Homework Equations The Attempt at a Solution Since the conductor cancels the field generated by...
  12. P

    Griffiths intro to electrodynamics Laplace's equation (boundary conditions only)

    Homework Statement A surface at z = 0 is held at potential V (x, y) = V0 cos(qx) sin(qy). Find the potential in the region z > 0. Homework Equations Laplace's equation in Cartesian coordinates The Attempt at a Solution I wrote at least a page of my past 2 attempts at a solution...
  13. kini.Amith

    Courses Course involving electrodynamics

    I just finished high school and i am very much interested in electrodynamics and electromagnetic waves and i would like to study it in greater detail..I am good at mathematics too.However, i don't like electronics, i.e, diodes, transistors and stuff. So what undergraduate course can i take...
  14. M

    Electrodynamics - Finding Surface Charge

    Homework Statement Consider a very thin flat plate positioned in the x-z plane. The plate is semi-infinite with an edge running along the z axis. The plate is held at potential V0. Using techniques from teh theory of complex variables a solution is determined to be: V(x,y) =...
  15. jfy4

    Electrodynamics question and maybe quantum/classical misunderstanding

    Hello, I have a question. I have being trying to get my hands on any QED book i can cause i love it! but once i found out that the electric and magnetic fields were actually quantized as photons, and that the force between charges is mediated by light, i asked myself a question which i have...
  16. K

    Experimental evidence of Gauss's law in electrodynamics?

    In electrostatic case, Gauss's law can be derived from Columb's law, so we can regard experimental evidence for Columb's law as evidence of Gauss's law. But what about non-static case? In this case we know columb's law is no longer valid, so we need experimental evidence to justify Gauss's law...
  17. S

    What are some recommended textbooks for introductory Electrodynamics?

    I'm looking to get a book on introductory Electrodynamics. I've already seen recommendations for This one: https://www.amazon.com/dp/013805326X/?tag=pfamazon01-20 But it seems really expensive. Are there any other good books for ED? Also, does intro ED require linear algebra?
  18. S

    Why should I learn classical electrodynamics?

    How important is classical electrodynamics to a good understanding of physics? Why should I bother to learn it if it has been replaced by QED? Also what are some good books for classical ED if It is in fact important to learn it?
  19. S

    Electrodynamics Method of imaging

    Hello all, I have recently been taught the method of imagging with opposite point charges. The stereotypical example of a point charge above an infinit conducting plate comes fine but i can't grasp the sphere example. It is shown http://en.wikipedia.org/wiki/Method_of_image_charges" , I...
  20. H

    Any good problem book on Electrodynamics & Thermodynamics

    I am going to take Electrodynamics & Thermodynamics for the next semester, I am wondering if there are good problem books with solutions on these topics? Any suggestions will be appreciated.
  21. M

    EM waves in matter (electrodynamics)

    I'm having some trouble understanding this module. It would be great if anyone could help. In a homogeneous nonconduction region where μr = 1, find εr and ω if E=30(pi)e[i(ωt-4/3y)] in z direction H=0.1e[i(ωt-4/3y)] in x direction I am to understand that for a homognous nonconduction region...
  22. M

    Quantum Electrodynamics - Achieving Graduate Level Understanding

    Hello fellow scientists and engineers. I am a Physics-EE double major at the U of MN (twin cities). I was originally focused on doing pure physics and obtaining a research position in academia or government, but various pressures have turned me from this path, causing me to pick up a second...
  23. M

    Solving Electrodynamics: Showing E Obeys Maxwell's Equations

    Electrodynamics q! Struggling with this module, if someone could get me started in the right direction that'd be great! An electric field is given by E(r,theta,phi,t)=A(sin theta/r)(cos(kr-wt)-(1/kr)sin(kr-wt)) in phi direction Show that E obeys all 4 of Maxwells equations in vacuum...
  24. R

    Mathematical treatement of electrodynamics

    I'm looking for something like Arnold's "Mathematical Methods of Classical Mechanics" that applies to electrodynamics/SR/GR. I'd prefer it exterior calculus based. So far, I'm leaning towards Thirring: https://www.amazon.com/dp/0387406158/?tag=pfamazon01-20 Anyone know anything about...
  25. K

    Physics problem with electrodynamics

    hello dear friends, i have another problem in physics, it has to do with electrodynamics. if we have a sphere with total loading Q which is uniformly distributed throughout it's volume, how can we find the voltage for R/2<=r<=R and for r>=R? (assume that we know E). i know that Va - Vb =...
  26. E

    How do I convert f(x) into its Fourier Transform?

    Homework Statement I am really confused in my electrodynamics class. I have the following function. f(x) = \delta (x + \alpha ) + \delta(x -\alpha) How do i convert this into Fourier Tranform ? Those are dirac delta functions on either sides of the origin. Homework Equations...
  27. R

    Hardcore Electrodynamics Class

    I'm just kind of curious how our school's E&M-I class compares to others because it seems like we are learning things at an advanced level (very fun though it can be intense). We started the year off with Special Relativity then went into Vectors; nothing weird yet. Then instead of doing...
  28. C

    How do two charged particles move in an electromagnetic field?

    A simple question: if we have two particles with opposite charge, and nothing else going on to affect the field, then how do they move? If they start out stationary with respect to each other, then they accelerate toward each other, and this current creates a magnetic field. That would slow...
  29. Q

    Jackson electrodynamics exercise

    Homework Statement An electron moves in a helix : \vec{r}(t)=v_{z}t \hat{z}+a e^{i\omega_{0}t}(\hat{x}-i\hat{y}), where a is the radius of the helix and v_{z} the relativistic z-component of the velocity. 1) Find the position vector of the electron in a system of reference that is moving...
  30. N

    Graduate Electrodynamics books

    Hi Folks J. D. Jackson's last edition to his Classical Electrodynamics (3rd edition) was ten years ago. Are most graduate physics programs still using his text? It appears that some programs maybe using Schwinger's book. What other graduate level texts are in use? Thank you
  31. Born2bwire

    Derivation of Lagrangian for Classical Electrodynamics

    Is there a derivation for the classical electrodynamic Lagrangian? I have taken a look at a few textbooks that I have on hand but all of them just state the Lagrangian (in the voodoo four-vector talk, \glares) without explaining the reasoning behind it. I know that the Lagrangian for a charged...
  32. M

    What are these physical quantites in electrodynamics?

    What physical quantities are these differential forms in classical electrodynamics? I read the paper ofhttp://arxiv.org/abs/physics/0005084" (A gentle introduction to the foundations of classical electrodynamics: The meaning of the excitations (D,H) and the field strengths (E, B)). The...
  33. M

    Amperes law and electrodynamics and Gauss's law

    It's evident that ampere's law is used to calculate the magnetic field produced by flowing charges. Can I use Gauss's Law to calculate the electric field produced by the flowing charges also? I ask this question because in the middle of a solid conductor, there is a flow of charge. However...
  34. N

    Read Electrodynamics by Fulvio Melia?

    Has anybody read https://www.amazon.com/dp/0226519589/?tag=pfamazon01-20? Why isn't it used as an alternative to Jackson's book? The only thing that is missing is that it doesn't contain problem sets (from what an Amazon reviewer mentioned), but that can be overcome by using problems from...
  35. B

    Looking for an electrodynamics text that includes vector calculus instruction

    Hello everyone, I wonder if a textbook like the one I described in the subject line exists - most of the classical electrodynamics textbooks I've looked at assume you already have a solid background in vector calculus. I'm trying to do a self-study in electrodynamics, and while I have taken...
  36. M

    Preparing for Jackson Electrodynamics

    I would like to know recommendations for the best way to prepare for Jackson's electrodynamics next Fall. I have taken Griffith's E&M as well as the usual undergraduate math (linear algebra, advanced calculus, complex variables, probability). I realize there have been some similar posts to this...
  37. T

    Some electrodynamics questions (waves)

    Homework Statement ok, for one of the prioblems I'm given the equations of an electric field: Ex(z,t) = E0sin(kz-wt) Ey(z,t) = E0cos(kz-wt) for a circularly polarized plane wave of light traveling in the z direction. I have to show the magnetic field, energy density, and Poynting vector...
  38. W

    Tips for learning electrodynamics

    Hi, I am taking an electrodynamics course. The textbook we are ussing is Introduction to electrodynamics by Griffiths. We are taking it from chapter 8. I am having an extremely hard time in learning it. Can somebody recommend me a few good books, webpages to learn? Also any tips on how to...
  39. I

    Two short electrodynamics questions

    1. Invariants in field strength The first part of the question asked you to calculate the Lorentz scalars by contracting the field strength tensor (F) and it's dual (G): FF, GG and FG (index's omitted) and formed ±2(B²-E²/c²) and -4/c(E.B). The next part asked: Are there any other...
  40. A

    LaTeX LaTeX: finding a script font a la Griffiths' QM and Electrodynamics

    This may sound a bit neurotic, but after trying the calligra and frcursive packages, I feel I'm still missing out on a good, general-purpose script font for math. I'm looking for something like the script "r" on page 9 of Introduction to Electrodynamics and the script "S" and "s" on page 121 of...
  41. T

    Electrodynamics: quaternionic potential?

    Hi! It's possible to construct a electromagnetic field, such that \vec{F}:=\vec{E} + i\cdot \vec{B}. Now the real part is the electric and the imaginary part is the magnetic field. Then, for example, the maxwell equations take the form \nabla \cdot \vec{F} = \rho, \qquad \rho \in...
  42. H

    What is Weber's Electrodynamics?

    Can someone tell me what Weber's electrodynamics is all about? I ran across it while reading Jackson's Classical electrodynamics. Thanks!
  43. N

    Does a Voltmeter Measure the Potential Difference Between Two Points?

    Homework Statement Hi all. Lets say a voltmeter registers (measures) the following quantity: V = \int_a^b{\textbf E\cdot d\textbf l} Does this mean that it measures V = V(b)-V(a), i.e. the potential at b subtracted by the potential at a? Thanks in advance.Niles.
  44. H

    [electrodynamics] rotating hollow sphere

    Hi, a homogeneous charged hollow sphere with the radius R and the complete charge Q is rotating with constant angular velocity omega around a fixed axle. How to calculate the magnetic field at the north pole? I have this hints: The ring current I with the radius small r excites on...
  45. Peeter

    Electrodynamics Lagrangian. differences in sign in online references.

    In http://en.wikipedia.org/wiki/Covariant_formulation_of_classical_electromagnetism It is written: \mathcal{L} \, = \, \mathcal{L}_{\mathrm{field}} + \mathcal{L}_{\mathrm{int}} = - \frac{1}{4 \mu_0} F^{\alpha \beta} F_{\alpha \beta} + A_{\alpha} J^{\alpha} \,. a personal...
  46. N

    Electrodynamics: AC-circuits and Kirchhoff

    Homework Statement Hi all. Please take a look at the attached circuit. I want to find the current through the capacitor, and of course I will use Kirchhoffs laws for AC-current. In this case, ε(t) = ε_0*cos(ωt). My question is: If this was an DC-circuit, I would define e.g...
  47. N

    Electrodynamics: Amplitude of currents

    Homework Statement Hi all. Please take a look at the attached circuit. I've have found the amplitude of the current through the resistance to be: \left| {I_0 } \right| = \frac{{\varepsilon _0 }}{{\left| {R - \frac{R}{{\omega ^2 LC}} + \frac{i}{{\omega C}}} \right|}}, where ε_0 is the...
  48. F

    Where Can I Find a Crash Course for Electrodynamics?

    Is there anything like *crash course* for electrodynamics ?
  49. P

    Griffiths (electrodynamics) problem 4.19, part b

    When finding the polarization of the dielectric portion between the two plates using P=\epsilon_{0} X_{e}E, why would we use the E-field in the air portion (as is done in the solutions manual and here: http://www.getofftheinternet.net/s_10077.pdf ) instead of solving for the E-field in the...
  50. Zarlucicil

    What Is Galilean Electrodynamics and Its Controversies?

    Galilean Electrodynamics?!? I finished reading The History of Pi by Petr Beckman, thoroughly enjoyed it and wondered what other works/activities the author was involved with. Soo I eventually came across this thing called "Galilean Electrodynamics" (which Beckman apparently had a hand in...
Back
Top