Electromagnetic radiation Definition and 163 Threads

In the full internal reflection case where we have a refracted evanescent wave, If another object is nearby, then we could have wave tunneling phenomenon(frustrated total internal reflection). 1) So, how can the evanescent wave which does not transfer any net energy produce another wave at the...

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.

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"...

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.

How is a continuous chain reaction maintained within a moderator if it is not fissile material? Are the fissile materials mixed with the moderator or are they coalesced at the center of the surrounding moderator? If it is the latter, how would the surrounding moderator allow fissile material to...

In explaining x-ray diffraction of crystals, usually the approach is to consider the atoms absorb radiation and scatter it, at some angles constructive interference occur and bright spots can be observed. It seems that it is different from the diffraction of slits or gratings because in these...

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...

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...

Hi all, Does electromagnetic radiation actually carry kinetic energy? Looking around the web gives different answers. I have seen explanations like radiation pressure experiments as evidence, but this has been argued being effects from energy absorbed by the recipient. In case it does not...

Hello PPer's, I have been considering the effect to which electromagnetic radiation emitted from stars might play in the gravitational coalescence of galaxies. Surrounding every galaxy there must be a halo of electromagnetic radiation streaming outwards at the speed of light which diminishes...

Why is light viewed as both wave energy and particle motion, whereas other forms of electromagnetic radiation is only seen as waves? Light is just a small part of the spectrum, so, surely all electromagnetic radiation should be viewed in the same way.

This is from Wikipedia: 1. What is really meant by "self-propagating", how it works? 2. How many electric and magnetic fields are in one wave? 3. What is the strength of those electric and magnetic fields? 4. What does -q and +q represent in the above diagram? 5. Why would...

I have a solid foundational understanding of far field electromagnetic radiation i.e., two in phase electric and magnetic fields oscilating perpendicular to each other and to the direction of wave propagation. However, I have some ambiguities regarding near field electromagnetic radiation and...

Can you make an educated guess on the amount of energy in the universe in the form of electromagnetic radiation (photons), considering the vast amount of photons moving in every direction throughout the vast universe, there is literally no point in the universe that you can be in and not observe...

Since we can observe gravitational lensing and conclude that mass can affect the path of EM radiation it seems logical to me to assume that EM radiation will exert a slight gravitational attraction of it's own on a mass,- although I do not recall ever reading about this. Presumably the...

Why do we often treat the electromagnetic radiation effects on Hamiltonian of a matter as a perturbation? In the other words, why the effects of radiation is so little that is treated as a perturbation?

This isn't really a homework question, but I felt it was better suited here than in General Physics. I'm looking for more of a general explanation than anything. I was able to do my homework for this section on my own (mostly), but I feel like I still really have no idea what is actually going...

Hello, I am having a lot of trouble in determining the difference between an electromagnetic field and electromagnetic radiation. Is an electromagnetic field caused by electromagnetic radiation within the space of which the field acts over? However if I am right a point charge that is not...

Bear with me, I am a chemist :shy: As far as I understand, every accelerating charge emits electromagnetic radiation. In mass spectroscopy charged molecules/parts of molecules move in the magnetic field which bends their trajectories using Lorentz force. That means they are accelerated...

By De-Broglie,light also exibits matter property. According to him, wavelength=planck's constant/ momentum. And again momentum is the product of mass and velocity. We again know that, mass of light i.e. photon is zero. Then from De-Broglie's equation, is the wavelength of light infinity? If...

I’m searching for a book about the applications of electromagnetic radiation. A more specific topic I’m interested in is radio antennas but I’m searching for a book concerning more than 3 different applications (eg X-rays, microwave ovens and radio antennas). It should include equations and the...

Hey all, my first post here. I'm 17 years old and am taking physics at A level. (Just finished my end of year exam today) So the understanding I have of light is that it is the oscillation of an electric field and of a magnetic field perpendicular to each other. I've come to the conclusion...

I don't understand this: According to what modern physicists believe to be true, there is entropy that slowly converts all energy of the universe into heat that cannot do any work. Than this heat is radiated as infrared light into space. Correct? Besides infrared heat radiation, start also...

does every electromagnetic radiation consist of photon?

What law is being obeyed by emr traveling out from a source eg a magnetic field does not get emitted from a magnet, why does a magnetic field get emitted (eg travel outwards at speed of light) from the alternating magnetic field present in a light bulb for example? I would appreciate any help...

Homework Statement Hey all, I am working through a derivation that my professor gave me to do and I am having trouble understanding one of the formulas that he gave me, namely: "EM waves can be described as: E(x, t) = Eosin(2πx/λ)*sin(2πc/λ)" The the Eo*sin(2πx/λ) term makes sense to...

iTunes University layman looking for answers and willing to do the work – just need some direction. I now understand electromagnetic waves can be created when molecules vibrate – which they all do. I understand the frequency of the light correlates to the frequency of the molecular vibration –...

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...

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...

I've always struggled with the commonly used measures of the intensity of electromagnetic radiation and it's catching up to me lately. Suppose \bar{P}(R,\phi,\theta) is the Poynting vector of an electromagnetic field (in spherical coordinates) with norm...

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

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...

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...

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...

Ok, so here is my question. Basically I believe that frequency and amplitude have no effect on each other. But in a black body, the intensity of the radiation is directly affected by the wavelength. With the intensity being the square of the amplitude, and wavelength being the inverse of the...

When Gamma Rays collide it is possible to form various units of matter (ie proton, electron, etc). Does anything happen when photons collide that are of other frequencies other then a ricochet? If X-Rays collide with other x-rays does anything happen? Also, if anything does happen, what would...

1. In the theory of electromagnetism, we say light(and others with different λ) propagates through anything by the alternation of the electric and magnetic field... I am still reading things abt the theory,haven't finished yet... But some things seem not clear... It seems 'em' is saying the...

Homework Statement Which of the following will produce Electromagnetic radiation? Explain Your answers. a) Alternating current in a TV transmitter b) The cord of a vacuum cleaner while it is being used c) The circuit of a battery operated CD player d) A positively charged particle...

Say I were to shine a laser in a particular direction and quickly turn it off. After a certain time, the radiation passes through a region of space. Some force field (e.g. electric or magnetic; assume gravity is negligibly small) is then turned on as the radiation passes, such that no mass or...

I recently read an article online stating that electromagnetic radiation is 'a form of energy emitted and absorbed by charged particles'. This isn't always correct, is it? I mean, I know that charged particles that are accelerating can emit bremsstrahlung and synchrotron radiation, but my own...

Homework Statement A quantum of electromagnetic radiation has an energy of 0.877 keV. What is its wavelength? The speed of light is 2.99792 × 10 8 m/s, and Planck’s constant is 6.62607 × 10−34J · s. Answer in units of nm Homework Equations E=hf v=fλ ... λ=v/(E/h) The Attempt...

In a nuclear reactor, what kind of energy is produced when the radioactive isotopes go through fission? How much of it is in the form of electromagnetic waves? Are the waves mostly in the UV and Gamma Ray region of the electromagnetic spectrum?

1. How do we observe what goes through in a slit in the double slit experiment? If this is accomplished with EM that goes across the slit, then why does the electron not completely change its direction before it hits the wall. It still always hit the wall where you expect it to, even though the...

Einstein stated in a paper concerning the discovery of the quantization of electromagnetic force that an object emitting electromagnetic radiation will lose its inertial mass. If this is the case, then why does the gravitational force of the sun not weaken and the sun not become less massive as...

Anything that occupies space creates a 'distortion' to a certain degree in the space time fabric and hence will experience gravitational force.And we know radiation does experience gravitation , this would directly imply that it occupies 'space' or 'volume' . The question now is .. how much volume ?

Could someone point me in the right direction on how low frequency (< 3 Hz) electromagnetic radiation is detected? I tried googling it, but my searches didn't really work; perhaps I was using the wrong terms? Another thing: what is the lowest frequency that has been detected, and what limits...

Hi, First post on these forums, but I've lurked a bit in the past. I'm doing a project on the Faraday Cage, and I have a quick question... I was wondering why a Faraday Cage can block electromagnetic radiation like a radio wave (which, as far as I can tell, is a "mix" of a magnetic field...

I have recently found a circuit schematic that can pick up radio signals without the need of a battery. Is this an example of electromagnetic induction? If so, how much voltage/current is induced? Does it change the properties of the electromagnetic wave, e.g. energy, wavelength, etc...

Homework Statement The positron and the electron each have a rest mass of 9.11 x 10-31 kg. In a certain experiment, an electron and a positron collide and vanish, leaving only electromagnetic radiation after the interaction. Each particle is moving at a speed of 0.20c relative to the laboratory...

Homework Statement Hello there! I have a couple of questions regarding light(EMR) and how it behaves when moving from one medium to another. From what I understand, the frequency of any light wave, when it moves from one medium to another, stays the same. As a consequence of this, the velocity...