Electromagnetic Definition and 1000 Threads

  1. Y

    Electromagnetic Induction in a disc

    Homework Statement Please see the attached file.Homework Equations $$\frac{dΦ}{dt} = ε$$The Attempt at a Solution The only way I see is to apply some conservation of energy. But I don't know how. The potential energy is being converted to rotational energy. But how do I find the potential energy?
  2. darida

    Components of The Electromagnetic Field Strength Tensor

    Source: http://gmammado.mysite.syr.edu/notes/RN_Metric.pdf Section 2 Page: 2 Eq. (15) The radial component of the magnetic field is given by B_r = g_{11} ε^{01μν} F_{μν} Where does this equation come from? Section 4 Page 3 Similar to the electric charges, the Gauss's flux theorem for the...
  3. darida

    Electromagnetics in Spherical Symmetric Problem

    In a spherical symmetric problem the only nonzero components of the electric and the magnetic field are Er and Br Why?
  4. paulo84

    Electromagnetic spectrum/(dark)matter/4 fundamental forces

    OK, I need some help understanding some stuff. The way I see it: you've got 4 fundamental forces in physics right? I believe these are gravity, electromagnetic, strong interaction and weak interaction. The electromagnetic spectrum is basically waves with photons (photons in all of the...
  5. E

    What is the intensity of an electromagnetic radiation?

    How can I compute the intensity of an electromagnetic radiation if I know ##e_x, e_y, e_z, h_x, h_y,## and ##h_z##, where ##e_i## is the electric field component at ##i## and ##h_i## is the magnetic field component, also at ##i##? Thank you in advance.
  6. S

    Electromagnetic Radiation in Space

    I'm not sure where to ask this question or if it even makes sense... Say an electromagnetic wave passes through a point in space. The point experiences some fluctuation of electric and magnetic fields. But what happens after the wave has passed? Are there any lingering effects, like a "wake"...
  7. S

    Software package for modelling electromagnetic interaction

    Hello! I would like to ask about any software package, where interaction between a moving particle and a monolayer can be simulated. What i need to get is a spectral angular density distribution in the far-field zone within optical frequency range for a problem when a particle crosses a...
  8. T

    Pulsed electromagnetic field indicator

    I just found this forum and would love some help on creating an indicator that lights up when placed next to a pulsed electromagnetic field. I'm thinking a small LED that lights up when placed near a pulsed electromagnetic field to confirm the electromagnetic field is active. How would I...
  9. jijopaul

    Electromagnetic wave... How is it getting transmitted?

    I've heard that em wave consists of mutually perpendicular electric & magnetic oscillations. Imagine that I've a unit charge at any point in space. Associated with this charge, there exists an electric field which diminishes with distance from the charge. If we set forth an oscillation in this...
  10. M

    Help with radio waves and electromagnetic fields

    I need help explaining that this assumption is not correct or correct: A product uses Radio waves to turn on a LED. Radio waves can be a form of electromagnetic fields therefore, a Hall Effect sensor could be used in this device to turn on that LED.
  11. J

    Classical Book like Barret/Bekefi's Electromagnetic Vibrations?

    The book is expensive, so I want a book like Bekefi's and Barrett's Electromagnetic Vibrations,Waves,Radiation. Preferably at a higher level than this book. Thank you!
  12. ulfurh

    Help with electromagnetic musical instrument design

    Hello everyone, For the past 4 years I have been working on a new type of musical instrument that fuses together elements from electronic music into the acoustic realm. The instrument consists of 26 strings inside a wooden enclosure that are actuated (or "bowed") by the use of electromagnets...
  13. E

    Electromagnetic nature of light

    I was recently taught in school about the propagation of light as a combination of changing electric and magnetic fields. I had read somewhere that a magnetic field was basically an electric field in a moving frame of reference. So,I wanted to know if in some frame the propagation of light could...
  14. S

    Electromagnetic Induction capacitor

    Consider the arrangements shown in figure in which the north pole of a magnet is moved away from a thick conducting loop containing capacitor. Then excess positive charge will arrive on : (Plate B = answer) Am i correct in marking the side facing the magnet as south pole? ( because of Lenz...
  15. godzenon

    Protons and electromagnetic attraction in the LHC?

    Thanks for reading this As protons go faster and fast in the LHC they have a greater angular momentum (that's not at all the right term) to go around in circles faster and faster as they reach near the speed of light that greater inward attraction towards the magnet to rotate around in the LHC...
  16. B

    Electromagnetic propulsion. (Not?)

    Hi folks, This is such a simple idea that I know I can't be the first to think of it so there has to be a "gotcha". Maybe an induced electric field working in the opposite sense? Is there a kind soul out there who can spare a few moments to educate me after reading what follows? Thanks About...
  17. 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?
  18. USeptim

    Electromagnetic field 4-momentum density and inertial frames

    Electromagnetic field has a density of energy U = ε/2*E2+ μ/2* H2 And a density of momentum, given by the Poynting vector S = E x H For an element of volume dV you have a four vector of energy and momentum which is [E,P] = dV * [U, S] Being E the energy in the element of volume and P the...
  19. Dvorak

    Magnetic field created without an electromagnetic field?

    Magnetic fields are less harmful than electric field and also a lot safer than being exposed to electromagnetic radiation. If data transfer is possible through magnetic flux then cancers and all those kind of diseases can be avoided. So, the question again is can a magnetic flux(movement of...
  20. B

    How Is the Divergence of J Derived in Electromagnetic Fields?

    Homework Statement In a book I find the following derivation: \int (J \cdot \nabla ) \frac{\bf{r} - \bf{r}'}{|\bf{r} - \bf{r}'|^3} d^3\mathbf{r'}= -\sum_{i=1}^3 \int J_i \frac{\partial}{\partial r_i'} \frac{\bf{r} - \bf{r}'}{|\bf{r} - \bf{r}'|^3} d^3\mathbf{r'} \\ = -\sum_{i=1}^3 \int J_i...
  21. Mr Davis 97

    Is a battery needed for electromagnetic induction?

    I am just scraping the surface of electromagnetic induction, and I have some questions. First, let me illustrate what I know. I know that in a simple circuit with a battery and a switch, when the switch is turned on, a current flows which produces a magnetic field of strength in proportion to...
  22. mgkii

    Energy at zero axis in an Electromagnetic field?

    Can someone correct my understanding on electromagnetic waves please; I've clearly got the wrong end of a stick somewhere, but can't figure out where my misunderstanding is! Thanks. If I draw a classic EM wave with the electric field on the up and down axis and the magnetic field at right...
  23. A

    Homemade Electromagnetic Sledge Hammer: Build & Power Needs

    Hi, I would like to make a homemade electromagnetic device. It would be a 5cm diameter metal cylinder inside of a metal pipe. I would use electromagnetism to lift the (heavy) steel cylinder up the pipe, and then release it. It's meant to be used as a sledge hammer. Can I just wind a wire...
  24. pvp042

    Electromagnetic effect on gases

    Are there any research or paper regarding electromagnetic effect on gases. For example does H2 gas physically move under electromagnetic field?
  25. D

    MHB How Does Coil Orientation Affect Induced EMF in Electromagnetic Induction?

    hello guys! I am confused about determining the equation for the induced emf in a rectangular coil with n turns rotating in a uniform magnetic field. According to faraday's law of EMI the emf induced in a coil of wire is the rate of change of flux passing through it $E_{induced}...
  26. nilesh_pat

    Storage of Electromagnetic waves

    Is there any possibility of storage of electromagnetic waves ? With regards Nilesh.
  27. itssilva

    Electromagnetic tensor and energy

    From introductory courses on EM, I was given 'sketchy' proofs that, in a EM field in vacuum, magnetic energy density is B² and electric energy density is E² (bar annoying multiplication factors; they just get under my skin, I'll skip them all in the following). Other facts of life: -FμνFμν, the...
  28. F

    Atomic electromagnetic simulator

    hello is there a software that simulates electromagnetic field around atoms, materials? to simulate the forces that drive chemical reactions? thanks!
  29. C

    MHB How Does Snell's Law Predict Light Behavior Across Multiple Layers?

    In the attached figure, light is incident at angle {\theta}_{1} = 40.1^{\circ} on a boundary between two transparent materials. Some of the light travels down through the next three layers of transparent materials, while some of it reflects upward and then escapes into the air. If {n}_{1} =...
  30. 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...
  31. R

    Electromagnetic Wave Calculations

    Homework Statement A monochromatic, electromagnetic plane wave is traveling in a non-conducting, transparent medium. Its real electric field is described by: ##E=100 \ cos (7.62 \times 10^6 (x+y+z) \ - \ 2.98 \times 10^{15} t) \ \frac{1}{\sqrt{5}} (\hat{y} + 2 \hat{z}) \ V/m## (a) What would...
  32. J

    Electromagnetic Induction Project Help

    Hi, trying to http://physics.stackexchange.com/questions/189766/teslas-egg-of-columbus# Tesla's egg of Columbus for a science project (). I have managed to cast a small rod of solid aluminium into a solid egg shaped piece of aluminium. I also have a large glass bowl that could sit inside an...
  33. N

    Excitation of electrons by electromagnetic source

    If you hit a bound electron with a photon corresponding to that electron's ionization energy, you ionize the electron. What if you hit the electron with a photon with less energy? Will the photon still add its energy to the electron? Will the electron re-emit the photon with less energy? Do you...
  34. J

    Raising Index of Electromagnetic Energy Momentum Tensor

    The General Relativity text I am using gives two forms of the Electromagnetic Energy Momentum Tensor: {\rm{ }}\mu _0 S_{ij} = F_{ik} F_{jk} - \frac{1}{4}\delta _{ij} F_{kl} F_{kl} \\ {\rm{ }}\mu _0 S_j^i = F^{ik} F_{jk} - \frac{1}{4}\delta _{ij} F^{kl} F_{kl} \\ I don't see how these...
  35. V

    Shouldn't a metal at 0K emit electromagnetic radiation?

    Electrons pile up inside a metal up to a maximum value in k-space (meaning the have velocity) and occupying all levels at 0K, solving the Schroedinger equation as running waves. So electrons moving => radiation being emitted. But electrons can't move to a lower energy state, so that would mean...
  36. F

    Electromagnetic field on molecule

    hello! it is known that static electrical field can change the direction of movement of water dripping, etc I suppose this can also happen with other molecules that are dipoles or somehow influenced by electrical or magnetic field my question is what are the equation(s) that describe this...
  37. O

    Complex reflection and transmission coefficient of EM waves

    I have a question about complex reflection and transmission coefficients. For example, I am modeling a wave in air (medium 1) ## \varepsilon = \varepsilon_0 ## reflecting on, and transmitted to, a medium 2 with ## \varepsilon = \varepsilon' -j \varepsilon'' ## If the wave would have traveled...
  38. Akmalidin

    Electromagnetic Waves: Coils, Transmitters & Energy

    I have coils to transmit and receive the power supplied.When we supply the transmitter , it omit the electromagnetic wave.Does it omit one electromagnetic wave or a lot of them? If there are several of them, is the energy supplied ,divided equally to the number of waves or every wave carries the...
  39. S

    Electromagnetic waves point to point propagation

    Is there a theoretical way to force electromagnetic waves transfere energy point to point like electricity instead omni-dirrectionally? I think it might be helpful for looseles wireless energy transfere.
  40. A

    Hamiltonian for a free electron in electromagnetic field

    hello, how to derive the hamiltonian for a free electron in electromagnetic field mathematically ? for a first step what is the lagrangian for a free electron in the EM field in classical mechanics ? the physics textbook always like to give the results directly.
  41. N

    Electromagnetic interactions and exchange particles

    Protons are in very close proximity with each other in a nucleus. This means there is constant electromagnetic interaction, of which the exchange particle is a photon. What determines the wavelength of this exchange photon? How do they exist in the nucleus: constantly being emitted, or staying...
  42. R

    Frequency: Electromagnetic waves

    Are the angular frequency in electromagnetic waves and frequency of a photon characterise the same physical quantity? I know that these come under two different theory, but I want to know whether these names (angular frequency of em wave and frequency of photon) mean the same physical quantity...
  43. V

    How to Show the Vanishing of a Term in Electromagnetic Field Energy Calculation?

    Hey everyone! I am supposed to calculate the energy contribution of the magnetic field term of an electromagnetic field. Basically the term is the following: \int_\Omega dx^3 (curl(\vec{A}))^2 And we can use the following two equations for simplifying: div(A)=0 and \Box A=0 So basically...
  44. daniel rl3

    How can electromagnetic waves be transverse?

    how can the electromagnetic waves be transverse and at the same time the E.M propagates in space (the definition of the transverse wave is that it is a wave in which it's medium particles propagate perpendicular to the direction of wave propagation) what i don't understand is that how can it...
  45. S

    How Do Longer UV Wavelengths Penetrate Deeper into Photopolymers?

    For a photopolymer, the heuristic goes that longer wavelengths of UV light penetrate deeper than shorter wavelengths of UV light. For example, the UVA spectrum penetrates more deeply into the photopolymer than the UVC spectrum. What is the best way for this to be explained?
  46. A

    Wire Attracts Loop - Electromagnetic Unit

    Homework Statement A rectangular loop of wire is placed next to a straight wire, as shown above. There is a current I in both the straight wire and the loop. The dimensions shown in the figure are a, b = 2.2a, and c = 8a. What is the magnitude of the force on the loop? Express your answer in...
  47. PhysixChick

    Electromagnetic Induction - Concentric Circles

    Homework Statement A small circular metal ring of radius r is concentric with a large circular metal ring of radius 10r. Current in the outer ring flows counterclockwise due to an unpictured power supply. By adjusting the power supply, you can adjust I, the current in the large ring. The graph...
  48. M

    Trying to understand electromagnetic waves in quantum theory

    I am an 8th grade science teacher who has regularly used the pre-Bohr planetary-like model of the atom (like most 8th grade science teachers and textbooks) to help students start to understand atomic physics. But in my free time, I have repeatedly tried, and failed, to really understand the...
  49. E

    Torque Analysis for Electromagnetic Retarder on MAXWELL 3D

    Hello everyone! I have a thesis about electromagnetic retarders. I need to do torque analysis for retarder; but I don't know how to do it on Maxwell 3D. I've tried Eddy Current solition; but analysis results didn't comply to electromagnetic retarder's torque charasteristic. Could anyone help me...
  50. I

    Is there an electromagnetic transducer to melt ice?

    Hi I have a project to were I would like to melt ice from several feet away. Is there an electromagnetic transducer that I can operate to melt ice? What resonate frequency would I need to use? Any ideas? Thanks
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