Emission Definition and 567 Threads

How many neutrino emission mechanism, that causes the cooling of star, are there in neutron star? And How, what equation, to calculate the emissivity of each mechanism? thankfully, First

Let's say we just had a normal atom in energy state E, and one of the electrons jumps down to a lower orbital E'. Of course, E - E' is positive because E' is a lower orbital than E, so the energy of the photon emitted must be positive. But what if E' were a higher orbital than E? Could the...

Based on the following excerpt, I'd appreciate any general comments/observations and then follow with a specific question. Leonard Susskind says in THE BLACK HOLE WAR, 2008, PG 347 : #: my parenthetical comment I knew physics was crazy, but that just seems "over the horizon" crazy...

I wonder is what are the legal and application area difference between "Tier","EPA" and "California" Emission Standard in U.S (I am not asking the allowable emission levels). Also, Is there any difference in on-road and off-road standads(again, I am not asking the emission levels)? Thanks...

Question regarding the emission of infrared radiation, for personal knowledge. Why do humans emit infrared radiation? Is it because it just so happens that the energy humans absorb (from sunlight)/ the energy humans produce just so happens to correlate to the frequency of infrared, as...

I keep seeing the hydrogen emission spectrum from the Balman series (when an electron falls to n=2). It's all over my textbook. Why don't I ever see the Lyman series or any other series? Is it really rare for hydrogen electrons to fall to energy levels other than n=2?

Suppose I have a two-level atom trapped in a certain area, initially in ground state. I have a light shining on it, the atom jump from ground state to the excited state and emission a photon spontaneously. Can I say this is a scattering process?

Hi there! The experiment: I'm counting Gamma and beta rays emitted from gamma and beta cylindrical sources, for counting I'm using a simple GM counter, which has nearly the same cylindrical shape (i mean diameter). As we all know this are electromagnetic emissions, so they distance must...

Hi all, I'm doing a project that includes an hydrogen 2s->1s decay and I need the full derivation of this process, so if anyone can recommend about a book it would be great. I first thought it should be easy to find but to tell you the truth I have looked and found scratch. 10x a lot...

Homework Statement Hi, I need to know the correct SI units for Einstein Coefficients (A and B) for stimulated emission (say laser). The equation I'm on about is Homework Equations \frac{A}{B} = \frac{8\pi h\nu^{3}}{c^{3}}The Attempt at a Solution after some scribbling I got to \frac{A}{B}...

Homework Statement Part a) The emission spectrum for Sodium lamp contains a reasonably bright red line in its spectrum. What is its origin? Part b) The possible transitions between electron energy levels for Sodium were analysed. There were no transitions between the s series (s subshell)...

I was doing an undergrad experiment on the sodium emission spectrum and I have a few queries. Of course, I was asked to analyse the famous yellow doublet which I'm on top of. I was also asked the analyse the diffuse series which was fine too. What I did notice however, was a strong red line...

A hypothetical atom has five energy levels. How many emission lines will it produce?

Is it possible to find out the relative concentration of c02 by looking at the emission or absorption from a hot gas, T = 1000K, containing among other C02? What I want to find out is if the emission depends linearly on the concentration. (in the IR region) What theoretically equations may I...

What is the main physical difference behind these two theories? 1) I understand that the thermionic emission theory is applied in metal-semiconductor contacts and heterostructures where the energy band off-sets are large. Whereas the diffusion theory is applied in a simple homojunction, of...

So I'm preparing to run an experiment involving Ionization. Unfortunately during my research, I've found out that when air is ionized (much like a lightning strike) it produces ozone. I learned that ozone molecules are unstable and usually dissipate back into O2 molecules in about 20 minutes...

Hey what's the relationship between the width of emission lines and the uncertainty principle? My lecturer mentioned it briefly but didn't go into it. I think I get it but would have trouble explaining it. Cheers, nSlavingBlair

k my physics background is limited , I know that photon emission is when the electron moves down in energy level thus releasing a photon but how does the photon get inside the electron , the energy that moves the electron into a higher level when this energy moves the electron out their...

*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...

Hey every one. I have problem in caculating the soot content in (gram of soot)/(1 liter of exhaust gas). Euor 4 emission standard of PM emission for HD diesel Engine is 0.02 g/kwh (from wikipedia) So, If I have an engine rated 200kw, the PM is also 0.02g/kwh, Exhaust flow is 1000CFM then...

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...

I've been obsessed with the derivation in the attachment for hours now, all rights & credits to the one who came up with it, but I completely can't follow it. How does one get rid of the e's and epsilons?! How to combine the momentum and energy equations? Squaring gives for me just onworkable...

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...

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/neo/dictionary/emission.htm All of which indicate a temperature of 280K and peak clearly...

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 =...