Absorption Definition and 495 Threads

I have been recently trying to advance my understanding of thermodynamics, but i have encountered a problem when it comes to absorption heat pumps and similar systems. The standard heat pump requires an energy input, to move heat energy from one location to another. Most would consider...

Homework Statement I am currently doing a biology honours project at university and have been stumped by a fairly basic physics hurdle. I need to know the equation to calculate the amount of light absorbed by water/unit depth. I have tried to find the equation all over but cannot find...

I have been wondering how to realize the color of a mineral by having the absorption Spectra... The following case is an example; The image is the absorption spectra of a Bolivian Amethyst which looks like this; [PLAIN]http://www.tequilabay.com/amethyst300lbbolivian.jpg I have tried...

Homework Statement The antimalarial drug quinine has pka = 8.4; is it likely to be absorbed by passive diffusion through lipid membranes in the stomach (ph = 0.9) or ileum (ph \approx 8)? Why? Homework Equations n/a The Attempt at a Solution If the pH of the environment is...

This is probably a really basic question, but I realized I'm not sure what the answer is. What is the mechanism for light heating an object? Are photons always absorbed by electrons (if they are absorbed at all)? Maybe this will help explain my question: People often say that infrared light...

This thread is related to another question that I have been pondering. In most objects that we experience on a daily basis (a green shirt for example), we know that most of the frequencies of light striking the object are absorbed. I simply can't believe that the atoms in the shirt have...

Linearly polarized light does not carry angular momentum. However, individual photons emitted, say, in the direction of the X-axis, carries a spin angular momentum \hbar in the direction + X or -X. And, when absorbing of the photon, target gets its energy h\nu and its angular momentum \hbar. Is...

what is the practical use of the concept of band gap other than classification between material? can free carrier absorption be manipulated by changing band gaps?

Hi I'm self-teaching calculus and I'm looking at exponential growth and decay. The differential equation for relationships like these if this was related to time is dP/dt = -kP i.e. the rate of change in P with time decreases at a rate which is proportional to the amount of P present. I can...

I have a very basics question. I have a question about absorption in molecular bands. When looking at spectra in the infrared region and comparing it with simulated spectra, I can see that some lines get partially absorbed and then grows to fully absorbed in the "center" of the absorption...

The diagram (see attached) represents some of the energy levels for an atom of a gas. White light passes through the gas and absorption lines are observed in the spectrum. Which electron transition produces the absorption line corresponding to the lowest frequency; A. E3 to E2 B. E2 to E3 C...

My textbook says "absorption yields color. emission yields fluorescence" - can someone explain what that means exactly. I know color is when something absorbs all wavelengths except one, which gets reflected and produces color. If it helps... the chapter is on bohr's model.

Homework Statement A naked person, whose skin area is 1.7 m2, sits in a sauna that has a wall temperature of 61oC. If the person’s skin temperature is 37oC, find the net rate at which the person absorbs heat by radiative transfer (assume an emissivity e of 1). How much liquid must the...

Why do the chlorophyll in land plants absorb primarily in the blue and red wavelengths, http://en.wikipedia.org/wiki/File:Solar_Spectrum.png" ? Isn't more energy available in 500nm green light vs 700nm red light? E =\frac{hc}{\lambda}

Hi, I'm trying to find out the total number of solar neutrinos that interact with the human body per second or per lifetime. I know we are exposed to many, most which pass straight through us, but I'm interested to know how neutrinos interact with matter. Thanks.

I have several electronic spectra for different cobalt complexes which I need to analyse. I am fine with finding \lambdamax and the molar absorption coefficient etc. However it also asks me to mark absorption bands on the printout and tabulate \lambdamax values and absorbance values for these...

Hi readers, I'm confused about some aspects of absorption spectroscopy, and hoping someone can de-confuse me First, just a preliminary question; am I right in thinking that when an electron absorbs a photon, the electron will then emit a photon of the same frequency and energy as the one...

Does it work like that.. that a changing EM field in-phase (actually, like.. 180 degre (spell?) out-of phase) with the incoming photon would absorb it? .. when sound waves of 180 degre.. (spell) out of phase with each other would cancel each other out. The same thing would happen with EM...

I have a question. We claim that the wavelength of a photon must exactly match the difference between the states of an atom or molecule. Then why are the peaks in the absorption spectrum of chlorophyll so broad? Shouldn’t they be very sharp?

I have a 3D graphics book, which gives the formula for absorption of radiance along a ray. I am trying to derive the details and would like to see if my derivation is correct. Let o(p) be the probability density that light is absorbed per unit length at point p. They give the formula as...

For an upcoming experiment I was given the following formula to study It shows the collisional radiowave absorption in the ionosphere although I don't really understand what it means. I have not come across it before and its not in my textbook. Can someone familiar with it please explain to...

How can I tell the difference between a free electron that's absorbed one photon at E = hf and a free electron that's absorbed two photons at E = .5hf? If a photon at frequency f represents a '0' and a photon at frequency .5f represents a '1', then I could send out '11', have an electron...

Hi guys (and girls;)) I need your help... I really don't get the difference between a PhotoLuminescence and Absorption experiment. What kind of informations one can get from each experiment? Moreover, why generally photoluminescence experiments are carried on at low temperatures? Thanks...

Correcting Galaxy Luminosities for Absorption ?? As light from distant galaxies traverses deep space towards Earth, some amount of that light is absorbed by various features lying between that emitting galaxy, and Earth receivers. Those features imprint those galaxies' observed Spectra, with...

Could anyone help solve a problem how to find absorption lines in hydrogen atom from n=10 (n - principal quantum number). I know that not all quantum jumps of an electron in atom are possible, thus I don't know how many different emission lins will be from this energy level where n=10.

What does word "absorption" mean in the intestine? Water is absorbed in the intestine. most water reabsorption take place in colon. When they water is absorbed in the first sentence, do they mean water moving out from the intestine to blood vessels. When they say reabsorption do they mean...

Hello I am looking for a few textbooks to digest, I am learning the fundamentals of spectroscopy, in particular absorption spectroscopy of gases. Are there any great textbooks out there on these subjects? I feel I need a more solid grounding. Any undergrad would be welcome, as would any...

Energy "absorption" Hi, Apologies if I've misinterpreted / mis-read something here (not a physics student - just a general interest). Just hoping to be put straight on something fairly simple: Are atoms / electrons able to interact with waves ie microwave / radio waves? If so, are there...

Can anyone briefly explain that what is saturated absorption? What's the condition to have saturated absorption?

the way i understand it is photons excite atoms, causing them to increase in energy. i view this increase in energy as jostling of a atom causing more movement of its proton, neutrons, electrons. i realize a photon is a particle and a wave(in limited comprehension.) so should i view the...

If there is a "red" color ball people told me that if i shine white light on it the "red" color ball absorbs all the light and reflects "red" photons hence we perceive it as "red" colored Is this true? if this is right i want to know more details... what does reflect mean here? what does...

I have been wondering lately, as I am quite new to physics. If an atom dropped from it's first energy level back to it's ground state, and emitted a photon. Could a photon of the same wavelength excite the atom back to it's first energy level? What is the difference between emission and...

If I have a group of atoms in a high voltage field, and I want to use photon energy to aid the ionization of the atoms what wavelength(s) would best be used to have the highest ionization efficiency? The shortest wavelength available? Or the resonant wavelength for each excitation level?

My question concerns my understand of the mechanics of the absorption of Photons by the components of atoms. I will use a common real-world example to facilitate my understanding of the concept. 1. When a rock (for example) sits in the sunlight, the rock warms to the touch. I believe this...

If you're reading a graph of absorption coefficient(cm^-1) versus wavelength(nm), how can you dtermine if the solution is optically dilute? What about optically thick? Thanks Ben

I just have a quick question. Which way of Atom Excitation is more efficient? Photon Energy which matches the absorption peak(s)? Or Photon energy of a Shoter wavelength than the absorbtion Peak?

Why don’t emission and absorption properties of an atom cancel out such that no such spectral lines are seen. If electrons in atoms are excited from level 1 to level 2 and absorb energy at some specific frequency, why don’t they then emit that same frequency when they fall back down to level1...

Hi, I am designing an amorphous silicon solar cell and i wanted some pointers on how I should calculate the width of the intrinsic layer to get maximum absorption of light into my cell. I have designed my cell with the doping concentrations of p and n layer as 10^18 and 10^15 respectively.

Homework Statement prove that A v (B ^ A) = A Homework Equations V = union ^ = intersection ' = complement The Attempt at a Solution A v (B ^ A) = (A v B) ^ (A v A) (used distributive property) ummm yeah I am kinda lost from here. much help appreciated

I have only taken one very intro quantum mechanics class and the furthest we got was solving the Schrodinger equation for the Coulumb potential of the hydrogen atom. So we solved for the allowed energy levels and the wavefunction for the hydrogen atom. We also learned how using the...

How is the absorption coefficient per unit path length determined for excitation sites in a host crystal with an excitation site density of N and a bandgap of the excitation site equal to the photon energy? What I am trying to determine is how many photons will be absorbed for a given length.

Hi everyone, My very first post after simply using physicsforums as a (very) handy FAQ resource. Okay, so my question is probably pretty simple, but I've been unable to find anything on here already. How does a complex dielectric constant imply the absorption of EM radiation? I...

Question: Is it safe to say that if two photons were to simultaneously come in contact with a single atom, the total energy of the combined photons would be absorbed and then emitted as a single higher energy photon with a direction that is opposite that of the average angle of incidence of the...

Homework Statement A refrigerator is rated at 370 W. What is the maximum amount of heat it can absorb from the food compartment in 1 minute if the food compartment temperature is 0 deg C and it releases heat into a room at 20 degrees C. Homework Equations COP=Qc/W W=Qh-Qc The...

What does the absorption rate of body tissues depend on? For example, at what rates would the rectum, vagina, mouth, and skin be able to absorb a certain chemical? Does it depend on the size of the molecule? If it is water-soluble does that make it easier to absorb? In fact, what makes something...

Does anyone know a good reference for absorption lines in the Earth's atmosphere at visible and NIR wavelengths (if there are any)? For example, perhaps in the range of 3500 Å to 8000 Å? I find that the search terms are too broad to give me reasonable results on ADS. I found some atmospheric...

Hi all, I have not seen a separate section for photonics, so I'll post my question here : Does anyone have measurement data of the absorption spectrum of (liquid) water in the wavelength range of 180 - 250 nm ? Thanks :smile:

hi i m studing AAS(atomic absorption specvtroscopy) technique.using beer"s law i plot a graph bw absorbance and concentration.then how can i make the quantitative analysis of my sample?

I've been wondering, if a photon is very far off any atomic resonances, can it still be absorbed by the atom? or will there be compton scattering? or will the photon pass through the atom? or is there something else I'm not considering... Thanks.

Homework Statement Steam initially at 120 oC is passed into 0.60 kg of water initially at 20 o C, and the total mass of water is just brought to the boil at 100C What is the mass of steam that has condensed? Ignore the thermal capacity of the container and heat losses. Homework...