Electromagnetic energy Definition and 30 Threads

I came across this video where Dr. Tyson talks about Nikola Tesla. Neil Tyson on Tesla. From 4:47 onwards, he says "We now send energy through wires", and talks about how bizarre it would be to walk around/stand in the way of such energy flow. Further he says the power transmission lines are...

The integrated Sachs-Wolfe effect occurs when a photon goes through a gravitational potential that changes due to spacetime expansion (presumably caused by dark energy). For that reason, a photon going through a gravitational well would gain energy (blueshift) when entering and it would lose...

Homework Statement An isotropic point source radiates electromagnetic energy, and its output is measured by a thin disc-like detector of radius R. Calculate the power measured by the detector at distance h from the source, assuming that the plane of the disc is orthogonal to the line of sight...

Dynamos and transformers have inductor coils reacting with changing magnetic fields and importing energy into the circuit in form of induced current 1. What about the counterpart of above principle in case of capacitors? 2. Will capacitors interact with...

1.There is an electric field between ionosphere and ground, also Earth's magnetic field is perpendicular to this E field, hence by poynting theorem integrating E x H across the entire surface of Earth gives a great deal of energy flowing west to east. 2. |S| = (E X B)/u0 = (150 V/m X...

Homework Statement For a home work assignment, I have to build a theoretical device which uses a laser to boil water. But I have no idea how to figure out how long it would take the device to transfer enough heat to boil the water. The laser diode has a wavelength of 445nm. We are supposed to...

Hello, I've been reading the Stern-Gerlach experiment, and where the concept of electron spin is introduced, am facing a problem, i.e., if you consider electron a charged rotating sphere, then the electromagnetic energy and size of the electron becomes huge! So how do you deal with this? Thanks...

Hey can I produce a electromagnetic radiation at 2.4 ghz from a 10 volt source then walk 25 meters away harvesting the electromagnetic radiation with a 2 foot copper wire turning it back in electrical energy to power a led

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...

I have to questions that I can't seem to understand. I've seen in my textbook the relation E=cB being deduced from Faradays law applied to some type of rectangular loop. The problem is this is done with regards to a planar wave. So is this relationship general for all EM waves? If so, how? And...

While I get the coherent and incoherent scattering process that leads to the bragg diffraction condition, I don't really understand the physical mechanism behind the transmission and reflection. Now, as I understand it, the bragg diffraction condition is satisfied only for one or two particular...

When we have a current in a long wire, what is the kind of total energy of the system? We do have an electric field inside the wire and a magnetic field outside it. I think the electric field has an energy, say E, and it is only this energy which appears also as magnetic energy and we don't have...

Does anyone know of reaction that can generate a a steady source of light? Preferably one easier to activate than burning of magnesium strips(which is too momentary anyway, I'm trying to make a chemical reaction that can eventually power a photoresistor/ light).

Say I have a volume of hydrogen gas that is raised to a temperature T so that 99.9 percent of the gas is ionized. If now, with the plasma at some pressure P, the volume is compressed a small volume dV such that no energy leaves the volume I'm curious of a total accounting of where the energy PdV...

We know that the conservation of electromagnetic energy is expressed via the continuity equation below: \large{\frac{\partial u}{\partial t}}+\vec{\nabla}\cdot\vec{S}=-\vec{J}\cdot\vec{E} with u=\frac{1}{2}(\vec{E}\cdot\vec{D}+\vec{B}\cdot\vec{H}) and \vec{S}=\vec{E}\times\vec{H} . It...

Homework Statement Find the electromagnetic energy and momentum density and their ratio. \\Determine the instantaneous values of the energy density, momentum density, intensity, and stress associated with the electromagnetic fields for the following cases. Also, identify these cases. Assume...

Hmm, not sure if this is the right place to be asking this. I am wanting to understand what effects electromagnetic energy can have when injected into the combustion process of hydrogen and oxygen? Can anyone tell me or point me what effects can occur or point me in the right direction to...

Hi all physics lovers, please bear with my question as its like a kid wondering about something :) Energy can neither be created nor be destroyed. So when I switch off an electric bulb, there is darkness. So where does the electromagnetic energy go? :confused: Thank you.

I have noticed in faraday cages and in microwaves that the holes in the screen manage to prevent certain frequencies from passing through them. Why it is that this happens?

Hi All Is the following statement true: Electromagnetic energy requires a wave medium to propagate. (The way free electrons in a copper conductor transfer energy in an AC circuit. Electrons can act as wave medium). If it is true, How does EM energy travel in space. Can gravity act as a...

some questions that have been bugging me: 1.Is there a beginning and an end to a photon? Does it take different amounts of time for different wavelength photon energies to be absorbed? would for example a radio wave photon be absorbed at a slower rate than a higher energy/frequency gamma...

electromagnetic energy saving space shuttle! hey! i found that if electromagnetic generators(made of superconducting wires) are enclosed in freezing nitrogen atmosphere(i.e at very low and constant temp.) in absence of any strong electric and magnetic field,maximum electric supply can be...

We are constantly surrounded by electromagnetic energy, right? In what way does this energy exist? Is it measurable? Is there much of it? Side thought, hypothetically, with a pole extended from Earth to outside Earth's atmosphere, couldn't the friction on the pole from "space" be converted...

I assume I am making a mistake here. Can you please help me learn how to fix them? In electrodynamics, the gauge transformations are: \vec{A} \rightarrow \vec{A} + \vec{\nabla}\lambda V \rightarrow V - \frac{\partial}{\partial t}\lambda These leave the electric and magnetic fields...

First off, I know nothing about physics so if this question seems bizarre, that's probably why! In theory, are there conditions that would permit electromagnetic energy to block or limit the passage of oxygen (normal, everyday oxygen levels)? Is electromagnetic energy denser than oxygen under...

In his Lectures on Physics, Feynman derives the electromagnetic energy density u and the electromagnetic energy flux \vec{S}. However, he states that there is an ambiguity in the field energy: the common expressions given for u and \vec{S} are only the simplest known expressions. There are...

Hi! I am looking for information about this : http://www.Newton.dep.anl.gov/askasci/phy00/phy00908.htm Electromagnetic energy of moving water & their interaction with other energy. Please, all links, books, advice or comment will be appreciated. Thanks a lot les

I am supposed to make a machine that encompasses different types of energies. I just have no idea what I can do for chemical energy and electromagnetic energy using household materials, for the most part. I was thinking possibly using a match for the chemical energy. Would have a solar powered...

I'm working on these problems can anyone help me with it? 1. In an EM wave traveling west, the B field oscillates vertically and has a frequency of 56.0 kHz and an rms strangth of 7.90E-9 T. What is the rms strength of the electric field? 2. Pulsed lasers used for science and medicine...