Electromagnetic Definition and 1000 Threads

Since temperature is no more than vibrating atoms (in Feynman's words), wouldn't that induce a changing electric field, just very slow in some cases? If so, is everything that is not 0 degrees kelvin radiating some kind of EM radiation? Like an ice cube, does it radiate small amounts of radio...

Hello, I am building a generator for a project in my physics class. I have lots of magnetic wire and 6 VERY strong neodymium magnets, their area isn't overly large (I'd say about 1.5x1.5 inches). How many coils would be best for me to make for the stator? I am making a circular spinning disk...

Hi all, I have a conceptual difficulty with the idea of induction of a current in a wire due to a changing magnetic field. Initially I was very comfortable with the idea. Upon seeing the typical setup of a square wire being rotated in a region of uniform magnetic field, I was happy to accept...

If we have a static electric charge, it generates an electric field. If that static electric charge is accelerating, it generates an electromagnetic field. What about if the electric charge is moving with uniform velocity? Is the field thus generated an electic field or an electromagnetic...

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?

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...

Hello everyone i bought a kit for my senior project on electromagnetic levitation. It uses an electromagnet to suspend a magnet via force of attraction. It is stable because of two hall effect sensors and voltage regulator. The kit can make the magnet move in a sinusoidal and tangential motion...

Here is a picture of a situation I thought of: The circles between the magnets indicate a wire with current flowing in the direction given. This picture is a cross section of a loop of wire, looking down. Not included in this picture is the battery and non-conductive connecting materials...

Hello, Is there any difference between 50/60 AC current and a 50/60 Hz photon stream/electromagnetic wave propagating through a medium ?? Regards, Hex

Hello, when a coil rotates in a magnetic field an AC is produced at the ends of the coil but do that electrons come from the coil wire ? If yes, shouldn't the coil run out of electrons after some time ? thank you

Consider a magnet moving towards a coil. We know that the motion of the magnet will induce a current in the coil and the direction of this induced current is to oppose the motion of the magnet. Now does the magnet experience resistance to its motion immediately as soon as it starts...

I've been wondering how does this motor work (if it is not hoax in the first place) I was thinking about Ampere's force but apparently it doesn't really have an affect here. Any ideas?

how friction is an electromagnetic force?

Has anyone come across an example where electromagnetic fields have been applied during crystallization processes. For example to modify crystal properties like magnetization or to change the polymorphism. In principle the use of electric / magnetic fields should change the formation of a...

This thread is to move this discussion away from another thread in order to talk about it in more detail, so here is a brief recapitulation of how that went to make an opening for the discussion... A photon is quanta of electromagnetic radiation, and despite the name, despite there are, I...

We know that 1)a change in current and voltage in a coil may result in induction in other stationary coil..this induction is directly related to frequency..ie The higher the frequency the more intense the induction effect. 2)we also know that there is no induction in case of DC current flow...

We can determine what kind of elements exist in different planets by observing electromagnetic waves from planets' direction, but does anyone have any suggestion on how planets generate electromagnetic waves at the first place? Does anyone have any suggestions? Thanks in advance for any...

ElectroMagnetic Wave In Liquid.. Help with Index of Refraction?? Homework Statement Consider the propagation of an electromagnetic wave in some liquid. The y-component of its electric field is given by Ey(x,t)=4.3 x104 V/m sin(5.40E-2m-1x + 6.00E+0 x106 s-1 t). How large is the index of...

I first thought that electromagnetic induction disobeyed the law of conservation of energy since there is another current created by another current by changing it (AC). but then there is Lenz law that says when you have yourself an current and also a changing magnetic flux, there will be an...

Homework Statement 1. Explain the effects To the photocurrent as the light intensity increases To the photocurrent as the frequency of the light is increased To the speed of the photoelectrons as the radiation intensity increases To the speed of the photelectrons as the radiation...

Dear friends i know that a wave is linearly polarized if its components have a phase difference of n*∏ and is circularly polarized if phase difference is n*∏/2. But what if phase difference is neither ∏ nor ∏/2? like for E= ax exp(-j(βy-∏/4)) + azexp(-j(βy-∏/2))... thanks in advance...

Imagine a stationary charge q located on the positive y-axis at a distance r from a stationary observer at the origin. Let us assume that the distance r is large enough such that the electrostatic field due to the charge is negligible at the origin. Now let us assume that the charge q is given...

hi, I try to use the Noether theorem to determinate the angular momentum of the electromagnetic field described by the Lagrangian density L=-FαβFαβ/4 After some calculation I find a charge Jαβ that is the angular momentum tensor. So the generator of rotations are (J^{23},J^{31},J^{12}) =...

An electromagnetic plane wave has an electric field and a magnetic field. Each component contributes equally to the energy density. Mathematically it is very straight forward to show this is true. The question is, "Fundamentally, why is this true?" Again, I'm not looking for a derivation...

Hi, my question is, if there is an interpretation for electromagnetic gauge fields, whose components are imaginary. This would lead to an imaginary magnetic field... Does anything like this exist? Or is it forbidden ny some first principal arguments? Thank you in advance for every input! Melvin

Hey all, just wondering over a very naive question but I couldn't really find the answer by looking through the web. So electromagnetic waves are self sustaining and they don't lose energy while traveling through space, except if the photons they're made out of do "collide" with matter which...

Is there a complex field that when properly interpreted yields the four components of electromagnetic vector potential, A_0, A_1, A_2, and A_3? Somewhat along the lines of the complex field ψ yielding information about a particles energy, momentum, and position probability. Thanks for any...

Yer.. I'm lazy and tired, did not enough research and found out that the radio/electromagnetic wave makes all the electrons move back and forth when the wave oscillates between the magnetic and electric fields... so you can see how much the current oscillates etc. But... um cameras work...

Can the magnetic wave have an influence on the electric wave?

Consider the time-reversal Lorentz transformation given by the 4x4 matrix: \Lambda_T = \begin{pmatrix} -1 & 0 & 0 & 0\\ 0 &1 & 0 & 0\\ 0 & 0 & 1 & 0 \\ 0 & 0 & 0 &1 \end{pmatrix}. In my relativistic quantum mechanics lecture, we discussed how the electromagnetic 4-potential...

Is there an equation for force due to electromagnetic radiation? For example, is there a force due to orange light?

Homework Statement Here is a question which frequently occurs on on our school test: "Prove Faraday's law of electromagnetic induction on the basis of principle of conservation of energy" I do not really know how to begin.Thanks!

First Post! So I was curious about how I could relate my new found knowledge of electromagnetic inductance on guitar pickups and I came across this on the internet: http://www.sciencebuddies.org/science-fair-projects/project_ideas/Music_p004.shtml#background Which says, "All of these...

Homework Statement In what units is energy density measured? 1. Watts 2. Watts per cubic meter 3. Newtons per meter 4. Joules per cubic meter Homework Equations E = cB (as derived by Maxwell) The Attempt at a Solution This question is so basic yet I'm confused. I thought...

A non conducting ring of mass m and radius R has a charge Q uniformly distributed over its circumference. This ring is placed on a rough horizontal surface such that the plane of the ring is parallel to the surface. A vertical magnetic field B=B0t2 τ is switched on. After 2 second from switching...

When an electromagnetic wave hits a conductor the transmitted part of the wave is damped considerably. I want to know if anyone can explain physically why the field is attentuated inside the conductor - i.e. what happens. I know the basic properties of a conductor: - Electrons free to roam -...

Lets take visible light for example. The frequency/wavelength determines the amount of energy and the type of wave(micro,radio,gamma ect.) The intensity or brightness is determined by the amount of photons. So what does the amplitude determine?

Hello, I know the electromagnetic field propagates in a 3D space so if I am horizontally aligned with the field I will receive its variation but what if I'm vertically aligned ? thanks

Just posting to ask if anyone has any tips to give for a student in a Junior level Electromagnetic fields class. We usually get about 10-20 problems/week and I manage to only get 6-7 of them done every time. Also, though I generally do well with it, I'm struggling to find the energy to read...

Hello everyone, I've been told many times that when the right frequency of electromagnetic radiation hits an electron, it is excited to another energy level. My question is this, "why do electrons get excited to higher energy levels when hit by electromagnetic radiation?" Why does the...

I can't represent me mentally what is an electromagnetic wave. I know that a mechanical wave is the propagation of a disturbance in a material medium and mentally I can see what it is. But electromagnetic ... Last year, I did electromagnetism. We studied Maxwell equations and we saw a...

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...

This is a question about electromagnetic waves and gravitational waves. Let's say we're on the Earth and we're looking up at the sun (safely). If the sun were --for some reason-- to violently and dramatically jerk from its position, how would we first find out? Would we first *see* the...

I have to do a presentation on why cellphones are banned in hospitals, and I'm going to have to explain how electromagnetic interference from the waves a cellphone gives off can mess with medical equipment. Can someone please explain the physics behind this?

My book takes a look at the maxwell equations in free space, shows that E and B satisfies the wave equation and then guesses on a plane wave as a solution such that you get a tranverse wave with E and B perpendicular to the direction of propagation. I don't know if I am too slow in realizing...

Please feel free to move this to the correct forum. After doing some reading, I've found that Electromagnetic radiation travels at the speed of light in a vacuum. EMR also travels in the path of a wave. Whereas, light and/or light photons travel in the path of a straight line. Having said...

I was watching the lectures on the MIT OCW course 5.111 where it was said that electromagnetic radiations are periodic variations of the electric field. Does it mean that when we are talking about electromagnetic radiation, frequency indicates how quickly do the electric fields change(their...

Can EM radiations produce repulsive effect on on non magnetic objects? If yes how can such fields be produced?

Can someone give me a high level defintion of electromagnetic radiation with some intuition on what the wave form represents (specifically the peaks and valleys)? I am comfortable with the electric and magnetic fields. I would like an explanation similar to the my intuition on the physical...

I am trying to figure out how I would go about finding the steady-state temperature distribution in an absorbing medium using the steady-state heat conduction equation: (1) -\nabla\cdot\left(K\nabla T\right) = q_{gen} where T is the material's temperature, K is the material's thermal...