Electromagnetic radiation Definition and 163 Threads

Hello, Perhaps my wording is a bit off so excuse me for that. I think it best to explain by way of a thought experiment. Say there is a device that counts the amount of photons with the same wavelength for all possible wavelengths. What is then the intensity vs. wavelength curve that I would...

So I'm doing a presentation soon discussing the horribly inaccurate physics of the movie "The Core", and in particular how they were able to maintain radio contact to people on the Earth's surface from within the center of Earth. This is obviously simply not possible as radio waves do not...

Homework Statement Find the energy densities of an electromagnetic wave separately for the contribtions arising from the electric and magnetic field components Homework Equations The Attempt at a Solution How does one do this? Is it just the usual derivation for a continuous...

For quite a while I have been wondering if the quantization of light may be due to the emission process. In that case, at first sight there seems to be no reason for radio waves (created with LRC circuits) to be quantized. But perhaps I overlook something? And would there be a way to test...

1. Can a solenoid connected to alternating current generator be used as transmitter of electromagnetic radiation? 2. Can a solenoid be used as a receiver of electromagnetic waves? I think point 2. is possible, since alternating magnetic field will induce voltage in the loops of solenoid...

Well, first of all, there are two ''kinds'' of electrons,correct? Valence, the ones furthest from the nucleus of the atom, and ''regular'', the ones most tightly bound to the nucleus. Light is generated as electrons ''spin'' in their orbitals, so if light is made when an electron is in a higher...

Why is the light assumed to be harmonics of the electric and magnetic fields rather than harmonics of the vector potential? Am I missing something? Whenever details about light are given in classical physics we are always told about second derivatives of E and B. Why isn't light given as a...

So heat is vibration of atoms in lattice (or fluid). Heat is also electromagnetic radiation. Do we say "heat is electromagnetic radiation", or is that incorrect, since heat is vibration of atoms in lattice? Should we say "heat is __spread by__ electromagnetic radiation instead?

Does electromagnetic radiation emitted by pulsars carry enough energy as to make the gravity created by these emissions significant enough to gravitationally effect distant objects many light years away? In other words, can a pulsar star or a neutron star, effect distant planets or even...

Homework Statement What is the peak electric field E_0 at 1 m from a 100 W lamp. Assume spherically uniform emission Homework Equations Magnitude of Poynting vector S = \frac{E_0^2}{c\mu_0} And Power = S x Area (2) The Attempt at a Solution Sub for S from (1) in (2) and...

Hello, this is a first year undergraduate student speaking, thanks for taking the time: 1) Is it unphysical (in a perfect realm, etc) to say "one EM wave"? With which I mean: an infinite mathematical line with for each point an E and B-vector defined varying sinusoidally. In other words...

I'm trying to explain heat and electromagnetic radiation to a group of middle school age kids. Would it be appropriate to describe heat as light that our eyes may not be able to "see" due to its wavelength, but that the nerves in our skin can percieve it as an incrased teperature? I'm looking...

the health hazards posed by electromagnetic radiation should be primarily dependent on three quantities: * frequency * duration of exposure * amount of waves the frequency and duration of exposure are easy quantities to determine. the question is how is the quantity, or density, of...

Homework Statement Electromagnetic radiation is emitted by accelerating charges. The rate at which energy is emitted from an accelerating charge that has charge q and acceleration a is given by: \frac{dE}{dt} = \frac{q^{2}a^{2}}{6\pi\epsilon_{0}c^{3}} where c is the speed of light...

According to wikipedia, "Electromagnetic radiation (often abbreviated E-M radiation or EMR) is a phenomenon that takes the form of self-propagating waves in a vacuum or in matter. It consists of electric and magnetic field components which oscillate in phase perpendicular to each other and...

Hello. I'm trying to understand electromagnetic radiation. Any help would be appreciated. From my understanding a photon is a basic "unit" of electromagnetic radiation with an energy corresponding to hv. Additionally radios transmit electromagnetic waves by sending an AC through an...

I know already that hot objects radiate infrared radiation, just to be clear. My question is, do all individual wavelengths of electromagnetic radiation heat objects that absorb that wavelength? Even if it heats it just barely, for the smallest fraction of a second.

So, I have a few questions regarding some of the laws of electromagnetism. While I was in school, one of my classes was Electrodynamics (as an ECE undergrad). We discussed how a current through a conductor creates both magnetic and electric fields (Maxwell's equations, among others, were...

Its well known that an accelerated charge emits electromagnetic radiation. Then why the orbiting electrons in atom merge in nucleus after some time.

I know that accelerated charges give off electromagnetic radiation, but does an accelerated (spinning) magnet give off electromagnetic radiation as well? If so, what is the energy loss from the magnet's kinetic energy?

Hello everybody. I've been having difficulty in understanding how an electromagnetic wave propagates through space. Firstly, from what I understand, electromagnetic waves are made up of a constantly varying electric field placed perpendicular and in phase with a constantly varying...

Hi, I am completing the study of telecommunications. As I've lost some lecture notes and I like to keep references on my bookshelf I am looking for a good book about Electromagnetism, electromagnetic radiation and radio communications. From the comprehensive online offer it is not easy to...

Hey there, I am not a physics student, nor have I ever studied physics. I have this question though (read thread title). I have googled for an answer but couldn't find any. According to Einstein, we are always traveling through the universe at the speed of light. When we are still, A...

Why can't light escape black holes? Isn't light as an electromagnetic radiation massless, thus not affected by gravitational pull? --

I have a question about the speed of EM radiation. As far as i understand, all Frequencies of EM radiation travels at the same speed. ie, will reach point A to point B in the same amount of time... But wouldn't that mean that as you go from one end of the spectrum to the other, the waves...

we know the total power of radition Radiation from an Accelerated Charge is p=2/3 (k e^2 a^2)/c^3 but what is the frequency of such radiation? and is that for the all observers the same?

Is light an electromagnetic radiation. If so< then isn't it casued by... IS LIGHT AN ELECTROMAGNETIC RADIATION. IF SO< THEN ISN'T IT CASUED BY Antipartlce/Partcle annhilation. please I am only an ametuer in particle physics and wish to deveolp more skills and understand more. Also, i want to...

Does anyone know a good reference which discusses the thermodynamics of electromagnetic radiation? Not blackbody radiation, or radiative transfer, but assigning thermodynamic quantities (temperature, entropy, free energy, etc.) to the field itself? The initial question is simple enough...

does the electromagnetic spectrum limited? whate is the theoretical answers for limitation of the spectrum?

[SOLVED] Quantum Theory questions... I have been having a bit of trouble on these homework questions 1)How many photons/s are contained in a beam of electromagnetic radiation of total power of 165 W when the each of the following is the source. (a) AM radio station of 990 kHz...

Homework Statement If electromagnetic radiation is made up of quanta, why don't we detect the discrete packages of energy, for example, when listening to the radio? Homework Equations N/A The Attempt at a Solution Does it have anything to do with the type of wavelengths or the...

Howdy, I'm no physicist, but I am a scientist by trade and some basic physics questions always bug me because I don't have any bases of understanding of the concepts. I apologize if these questions seem a bit abstract: Suppose an event occurs that causes the emission of EM radiation (for...

Is it true that "waves" don't have any physical existence, and instead are mental contructs used to explain the probability of a photon striking a particular point?

A question that I reckon will be fairly simple for you guys. Electromagnetic radiation originates from electrons going down different energy levels, correct? But then what determines the frequency and wavelength of that radiation?

1. Consider N similar antennas emitting linearly polarized electromagnetic radiation of wavelength \lambda and velocity c. The antennas are located along the x-axis at a separation \lambda form each other. An observer is located on the x-axis at a great distance from the antennas. When a single...

CCDs can capture visible/infrared/etc... EM radiation. Is there any way to visualize or capture lower frequency radiation such as microwaves or radio frequency radiation?

What is the mechanism that operates behind the production of electromagnetic radiations when charged particles are accelerated? How are electromagnetic radiations produced in this way?

I was just wondering why is the sunlight called the electromagnetic radiation. I posted this on other science forum but got no satisfactory answers. MY friends even suggested me to look at some detail on quantum mechanics and told me to look on quantum nature and refer...

Would the night sky appear dark if our eyes were sensitive to electromagnetic radiation with wavelength around 2 mm? Why or why not?

Would the night sky appear dark if our eyes were sensitive to electromagnetic radiation with wavelength around 2 mm? Why or why not?

Here is a link that shows how microwaved water is bad for a plant as compared to regular water. Wouldn't the radiation turn into heat in the water and when it cooled down leave? http://files.meetup.com/196633/MicrowavedWater_SeeWhatItDoes2.pdf

An Electromagnetic radiation has a frequency of 5.00x10^14 hx. a) Calc its wavelength in a vacuum in metres and nanometres b)Calc its wavelength in water c)is this radiation visible? if so wat colour? d) What is the index of refraction of a medium in which the speed of this radiation is...

Hi all, I am a newbie reseacher postgrad. My work will be the title above and is anyone know whether it falls in Quantum Mechanics or general Electromagnetic physics? Actually what is so different in Quantum Mechanics since I saw it seems having some corrrection in EM radiation/photon...

i need to know everything about electromagnetic radiation

The course website for part 2 of E&M says that this book will be used for the course. Have any of you used it? What are your opinions on this book??

The energy (in joules) of an electron energy level in the Bohr atom is given by the expression: E_{n}= -2.179 x 10^-18/n^2 Jwhere n is the principal quantum number for the energy level. What is the frequency in Hz of the electromagnetic radiation absorbed when an electron is raised up from level...

"An electromagnetic radiation has a frequency of 5 x 10^14Hz a) (wave in vacuum = 600nm) b) (wave in water = 440 nm) c) what is the index of refraction of a medium in which the speed of this radiation is 2.54 x 10^8 m/s?" so given: c = 2.54 x 10^8 m/s f = 5 x 10^14Hz...

Please i really need help I am sorry to have had to make a second thread but i really need to finish this. 2. The electron and positron each have a rest mass of 9.11 x 10^-31 kg. In a certain experiment, an electron and positron collide and vanish, leaving only electromagnetic radiation...

I'm sorry if this isn't the correct place to put this...newbie alert.:biggrin: I'm absolutely horrible with Chemistry...I try really hard to do it, really I do, but a lot of the time, I only end up completely baffled and frustrated. Currently, I'm to be filling out a worksheet using a link...

In reading about magnetic resonance imaging, I was surprised to learn that the coil/antenna used to send a radiofrequency pulse into the person being scanned is not a coil/antenna at one end of the person, but a large coil actually wrapped around the person. I know how alternating current...