Emission Definition and 546 Threads

*This isn't actually coursework but i was under the assumption that questions go to this forum* Homework Statement Hi, for while I've been under the impression that spectral lines of all the elements can be calculated. I did some research and found that there is a simple equation (Rydberg...

I am working of the Diesel Emission Project, however i have some problem in evaluating the filtraion power of the Particulate Remover Unit. The following is my question: What is Hartridge Smoke Unit (HSU) ? Could anyone can provide some picture of different level of HSU so that I can...

Classically, I think it is correct to say that Maxwell implies an accelerated electron will "radiate" What is the quantum take on this please? In particular, what determines the wavelength of the emitted photon? PS I may ahve asked something like this before, but I never found an answer...

I find now that there are several effects on light that are not explained by QED. This surprises me since Feynman was so fond of saying that it covered nearly all the physics we experience. So I expected to get an explanation for reflection when I watched his lectures or read his book on QED...

The pole still has extremely strong gravity, how can a sphere suddenly concentrate the radiation at the pole to be emitted there ? As this is the only exit, should there not be a strong deformation ? How does the radiation make it to the pole, or, is the radiation we are getting only from...

Hi I'm an MPhys Physics with Astro student, conducting my final year project in the field of radio astronomy (well, it's more like electronics at the moment - trying to fix a downconverter, but anyway...) My question: I'm interested in observing the 6.67GHz methanol maser emission. For a...

In order to detect SARS, airport officials would use infrared cameras to find potential carriers. A healthy individual would be detected to emit 100microwatts at 37C body temperature, what would a sick individual at 40C body temperature emit? With this answer, what is the difference in...

Can someone tell me about photon emission? If an electron bound to a nucleus emits a photon and drops to a lower energy level, in what direction does the photon go? - Does it leave the electron perpendicular to the tangent line of the electon's 'orbit' at the instant of emission - that is...

Are spontaneous and stimulated emission selected by a Boltzmann's statistics ? Consider 2 levels(m,n) oscillators in thermal equilibrium with Einstein's coefficients Amn (spontaneous emission), Bmn (stimulated emission), Bnm (absorption) and r(f) the energy density at the frequency f (black...

In my astrophysics book (Astrophysics, Nigel Ingham), there are intensity-wavelength graphs for line spectra (both emission & absorption). On the y-axis, relative intensity is plotted. But on the x-axis, frequency and not wavelength is plotted. Why is this? If I wanted to convert this graph to...

Homework Statement Basically, the problem states that a cavity at temperature T is emitting EM waves isotropically in all directions (with frequency distribution of Planck's Law). If the time averaged density is <e>, find the value of d<S>/dw where w is the solid angle and the quantity is the...

In a condition of high pressure, how could vary the Helium emission spectrum? Is this spectrum modified from the pressure?

I have run across two formulas for Planck's Law of Radiated Power Density. According to http://hyperphysics.phy-astr.gsu.edu/hbase/bbrc.html#c1" it is Bf(T)=((2*pi*h*c^2)/(lambda^5))(1/(e^(h*c/lambda*k*T)-1)) However, in one of your forums, the pi is missing as it is here...

Hi, In a few journals I've come across the term "centimeter continuum emission" - e.g. 21 cm continuum emission. What is meant by this? And how can it be continuum when it has a discrete cm value? Thanks, San

http://www.informaworld.com/smpp/content~content=a788582859~db=all G. V. CHILINGAR, L. F. KHILYUK, and O. G. SOROKHTIN, 2008, Cooling of Atmosphere Due to CO2 Emission, Energy Sources, Part A, 30:1–9, 2008 ISSN: 1556-7036 print/1556-7230 online DOI: 10.1080/15567030701568727 Heads...

Hello to every one. I'm presently embarking on a problem about electron emission under applied electric field. Of course, basically there are two mechanisms for electrons to escape into the vacuum from a sample: the thermionic and the tunneling. Here I'm concerned only with the latter. As usual...

an electron travels at 1 x 106 m/s. when it hits a target, its speed decrease in half and a photo is released. find the phton's wavelength. so far i know E photon = (hc) / lamda what about the speed? does the photons' energy same as kinetic energy of the electron which is just 1/2 mv ^2...

Hi all, I'm keen to find out more about electron ejection from metals. Eg multi-photon photoelectric effect and thermionic emission. I've come across a few texts (Kittel) which deal with them in a general sense but can anyone recommend a more detailed analysis? Some questions which I...

We have that the proper distance to an object is given by d_p (t_0 ) = c\int_{t_e }^{t_0 } {\frac{{{\rm{d}}t}}{{a(t)}}} and this goes for all possible universes described by the Robertson-Walker metric. Since we know that 1 + z = \frac{1}{a(t_e)} does this mean that the proper distance at...

Homework Statement If an LED is used in an optical communications system, explain what would happen to the temporal spread caused by material dispersion in the fibre as the LED is cooledHomework Equations (having trouble using the latex equation editor, sorry) I know that the temporal...

With 90% of the observable matter in the universe being Hydrogen (H2), why is it that the microwave background is attributed to the big band and not the emission of microwaves from excited state hydrogen?

Hi! I am reading about the Z^0 production and decay processes at the moment. I have understand that the Z^0 is produced at rest, and when it decays to two leptons (or quarks) they must be emitted back to back to conserve momentum. But when I look at real and simulated data, the...

Hello This is a question regarding photoelectric emission. When frequency of the radiation increases at a constant intensity, the number of electrons emitted per unit time decreases. Why is that so? p.s. I need an answer ample for Alevel purposes. Not too complex that is.

Homework Statement Do photoelectric effect suggest that the emission of energy by an atom be quantized Homework Equations The Attempt at a Solution I think it is true as photoelectric effect told us that atom emitt energy in terms of electron.

I don't really have a HW question, I am doing physics independent study and I have to do a project. My teacher suggested doing it about emission spectra, only, I have no idea what that is and searching EBSCO is not being really helpful, does anyone have any resources, ideas, etc where I could...

Hi, I have found several links using google to emission spectra of the Earth: http://lasp.colorado.edu/~bagenal/1010/SESSIONS/13.Light.html http://www.xylenepower.com/ http://spaceguard.esa.int/NScience/n...y/emission.htm All of which indicate a temperature of 280K and peak clearly at...

In order to produce stimulated emission we need a photon which has the same energy as the difference is the lower and upper energy levels in the excited atom. But how exactly the energy of the photon does have to correspond to the energy difference between the levels. Can stimulated emission...

What happens when a single atom emits a single photon? Does the photon itself exist as a spherical wavefront that propagates in all directions? Or is it ejected as a tiny, "vibrating ball"? In other words, is the spherical wavefront of a light source (like a star) just the result of the...

Homework Statement The problem involves an atom (Said to be in an excited state of energy Q_0) traveling towards a scintillation counter with speed v. The atom then emits a photon of energy Q and stops completely. The rest mass of the atom is m. I'm supposed to show that Q =...

In a lecture today our lecturer illustrated the idea of wave particle duality and gave some experiments that show evidence for the particle side of things. Namely photoelectric and x-ray tube. If I get this right the basic idea is that free electrons are accelerated through a potential...

Homework Statement Assume that a high-energy nucleon is emitting a pion, i.e. the process N→N+π. Is the pion real or virtual or both? Motivate your answer with a calculation or a good argument. Homework Equations Virtual particles does not obey energy (and momentum) conservation. The...

My understanding of analyzing emission spectra is that when the quantum number of an electron decreases (i.e. when it falls closer to the nucleus) it emits energy. I understand that this is a very basic understanding but I have not yet made it to college, so please bear with me. :) Now, what I...

"Waves" in spherical emission... Hi all, I just thought of this and wondered why it had never occurred to me before. In any source emitting EM radiation (a lightbulb for example), it does so all around it, so a sphere of EM radiation propagates out from the source. However how in the world...

my question is : How would you make a 1, 3, 5, 7ppm solution from a 100ppm solution? do i just just this formula: C1V1 = C2V2 to calculate the amount i need? for example, for 5ppm solution => (5ppm) V1 = (100ppm)V2 so for V1, I just choose my final volume to be whatever i like... like...

I was doing a test about rydberg constants using H2 and Hg light spectrum And in the spectrograph I found that H2 have three spectra and the Hg have 5 spectra And I DON'T KNOW WHY H2 have 3 lines and Hg have 5 lines? (Scientifically). I know it is the numbers of the electrons that...

Emission line is unique for all elements and i think it depends on the electrons of the elements...my doubt is if an element gains or loses one electron then would the emission line of this ionised atom and the emission line of its neighbor atom in the periodic table is same or not..since the...

what is Meinel system? and what is OH Meinel emission bands?

Good evening ladies and gents I'm in the process of wrapping my brain around Special Relativity, and I've come across an interesting application having to do with Cosmological Horizons. Basically, the question goes like this: "Assume a time T has passed since the Big Bang and that we are...

Hi. This isn't so much a homework question, but more of a conceptual understanding question. Lets say an atom has a ground energy level defined at 0J. The energy levels are: E1 = 0 J E2 = 7.77*10^-19 J E3 = 10.66*10^-19 J E4 = 14.1*10^-19 J E5 = 16.6*10^-19 J Now, if an electron...

If I make a ball out of calcium; drill a little hole in it; then heat it up in a suitable [vacuum] environment; I see black body radiation thru the little hole, right? At least up to the melting point of calcium ?? I mean, black body radiation is independent of material, right ? Yet the...

"glow" of emission lines vs. hot objects I was wondering how the mechanisms differ between the following two scenarios: A. The glow of emission lines (I think it has to do with the Bohr atom) B. The glow of hot objects (I think it has to do with Blackbody radiation)

"glow" of emission lines vs. hot objects I was wondering how the mechanisms differ between the following two scenarios: A. The glow of emission lines (I think it has to do with the Bohr atom) B. The glow of hot objects (I think it has to do with Blackbody radiation)

IF nothing can escape from a black hole's event horizon, then how do x-rays and Gamma rays escape? and how does it emits light? it says in "Brief History of Time" that the light it emits is just at the boundary of the event horizon. So then how does it escape the gravity and reach earth...

Homework Statement 1)Neutron emission is not a possible mode of decay for K(40,19).Why? Homework Equations The Attempt at a Solution I think it is because the neutron to proton ratio for potassium(40,19) is almost unity(more precisely N/P=1.1). So, neutron emission is not a mode...

Intensity of light constant..why rate of emission of electrons changes?? Intensity of light constant..why rate of emission of electrons changes as frequency of the incident light increased??... is the rate increase or decrease?? help me.. thanks..

I'm somewhat confused about the emission of photons when electrons go down an energy level. What sentence could I use to help me comprehend this process? This is what I was thinking: When electrons absorb photons from electromagnetic radiation, the electrons have more energy and thus it moves to...

Homework Statement Ok guys, Helping my girlfriend out once again. She(if you haven't seen this before) is in Physics 101...yet, I(have taken all engineering courses) can't figure these out. Their book is absolutely terrible! Please give an answer that I can understand(as I like to learn...

I was wondering about the process of atom excitement/ionization. If you have a atom that has 4 energy levels and a emitted photon from a laser that had the wave characteristics (F,L,E) as not the valance electron, but the sub shell below the valance electron (match the sub shell energy gap), can...

I own and have read numerous books about quantum electrodynamics and also classical EM. But sadly, I have yet to find a good book that describes how EM generates photon-based radiation. E.g. the process by which a radio wave comes into existence -- at a deeper level -- not just Maxwell...

I’m having some trouble with a question from my special relativity assignment. It relates to the frequency of a photon emitted from an atom which then subsequently recoils. The atom has initial rest mass m0, and loses rest energy ‘e’ in the emission (“e is the difference between the rest...