Attenuation Definition and 135 Threads

Hello, does anyone have a graph for the attenuation coefficient of Gold (Au) (y-axis) with the respective types of interactions with photons of various energies usually from~10^-3 to 10^4 MV (x-axis) and where the incoherent, photoelectric, compton etc...interactions occur? Doing work on this...

Hello, So I have a circuit where I input a square pulse with a source impedance and load impedance (which are just pure resistors) each of which can be varied and a transmission line circuit connecting them which is made up of resistors, capacitors, inductors in a lumped element model. I set...

Homework Statement This i self study! Hi, How thick should a foil made from absorber II be to give the same absoption as 1mm thick foil made from absorber I for xrays with energy 5X106 xray beam passing through an absorption material it is attenuated , this is given by I/Io e-ax io...

It is known that the penetration depth of photon into a material depends on the energy of the photon, density and atomic number of the material; because the photon energy is normally smaller than the potential against the penetration of photon, which is the potential barrier, so the incident...

For my waves and diffraction course we have had a completely incompetent lecturer. We were looking at standing waves and then all of a sudden he spent a lecture looking at attenuation, not mentioning where it would apply or explaining it particularly well. I have tried to find a textbook to...

I was wondering why light transmission through a solution decreases exponentially and not linear with the concentration of the absorbing compound in solution. I know the Beer-Lambert law, but I do not really understand the reason for this logarithmic rather than linear dependence. Can anyone...

Homework Statement Is there any way we can measure the thickness of an exposed PTFE membrane air sampling filter? An unexposed filter (from the filter datasheet) has a thickness of 40μm. We have 5 ambient air exposed filters with the following mass concentrations: 1μg/m3 (filter 1), 20.1 μg/m3...

Hi, I'm solving a problem numerically that takes the form Q_{ij} \ddot{y}_j +S_{ijk}\dot{y}_j\dot{y}_k +V_i=0, where (Q_{ij},S_{ijk},V_i) are all functions of the dependent variables y_i. The dependent variables are all functions of the variable t. The resolution of this spectral...

Homework Statement To protect the lunar base against space and sun radiation, astronauts covered it with 4m thick layer of regolith (moon soil). However, they found that they level of radiation was still 50% higher than on the Earth's surface, which they want to match. How many more meters of...

I'm revising attenuation and power loss logarithmic equations. The exam formula I'm given is attenuation = 10 log (I1/I2) I'm trying to confirm what each I stands for. Some of the examples I'm looking at seen to give input/output power, some seem to reverse it. Which is right? What do they...

Homework Statement problem 1 A 20 Hz seismic wave traveling at 3 km/s propagates for 2000 m from point X to point Y through a medium with an attenuation rate of 0.5 dB/λ. What is the ratio between the amplitude of the wave measured at X and the amplitude of the wave measured at Y (i.e., AX/AY)...

I am completing a radiological physics experiment about attenuation and half value thickness. I'm struggling to understand linear attenuation coefficient and what it means when it says its and exponential relationship. I understand that attenuation is the reduction in intensity of an...

Why does water attenuate sound waves more than air? Is it because of it's bulk modulus? This is what I understand. Speed through a medium is determined by the elastic component over the inertial component. Since water has a much greater bulk modulus (elastic component) than air, it makes the...

This is killing me; not sure if I'm over-complicating or under-complicating it. I’m trying to understand if there is any difference between acoustic scattering and diffusion, and how that differs from attenuation. When particles collide, a small amount of heat is created, since the collision...

Homework Statement Find the attenuation constant alpha, phase constant β, and phase velocity v if the conductivity of the material is σ=ωε the material parameters are μr=1, εr =2.5, and the wavelength in free space is λ naught = 30cm Homework Equations The Attempt at a Solution So...

Homework Statement It is customary to express fibre loss in units of dB/km: \alpha(dB/km) = \frac{10log(P_{in}/P_{out})}{L(km)} where P_{in} is the power entering the fibre and P_{out} is the power leaving the fibre. Show that \alpha(dB/km) = 4343\alpha(m^{-1}) The Attempt at a Solution...

Homework Statement I've attached the problem and my attempt at it as a picture attached. I've done part b.i) although I'm not sure if it's entirely correct. I'm struggling with the last part b.iii). This is where I have to calculate the thickness of aluminium instead. I'm given the atomic...

Sorry if this is in the wrong place. Was not sure what it is categorised as. I have come across the following:e^{-\frac{\omega}{c} nkz}, referring to attenuation of a wave. It was found here...

I have seen this concept in many places like electrical field, gravitational field, brightness from a distant star or in satellite communication. That is, they seem to be inversely proportional to the square of the distance from the source of that field. What's the reason behind it?

Hi, I have a question regarding frequency, power... Let's say I have signal with power level of X dBm and the signal has been attenuated by Y times. What is the correct formula to use to get the final power ? Thank You

Dear All, I am basically from Bio background and doing research in Insect Physiology as Phd. Currently I am given a task to generate artificial insect songs using a software. I did it with 3 v Noise stimuli(1.5 peak to peak) and fed it to amplifier and I heard it on Amplifier. So now the...

hello all first post here and I'm interested in some info you people may hold :smile: in layman's terms I'm trying to understand how a fixed line level can attenuate. according to wikis line level page the 'the signal out or line out remains at a constant level, regardless of the current...

Homework Statement http://img543.imageshack.us/img543/4598/photosfr.jpg Find dss, dsr and thus hs. Homework Equations trig The Attempt at a Solution dss = hs/(sin[θ]) dsr = hs/(sin[∅]) dss = 3.059/(cos[θ]) dsr = 47.191/(cos[∅]) θ = arctan(hs/3.059) ∅ = arctan(hs/47.191) I have tried...

I've been trying to get reantiquated with electormagnetics to understand RF communications better. I have a question about TEM plane waves. The funtions which describe the plane waves in the z dirrection are: e-α cos(ωt-βz) ; in the time domain where is the rate of decay. In free...

Homework Statement I have a 2 wireless cards with a power output of 0dBm, two 5dBi gain antennas, and a 30dB attenuator connected to each antenna. I need to figure out what the path loss will be in this scenario, so I can therefore determine the maximum distance possible between the...

I have read that the attenuation of water (for ultrasound) is 0.0472 Np m–1 (MHz)–2. What is this in dB/cm/MHz^-2 ? What is Np? thanks

I recently did an experiment where I had a T-type attenuator. It was connected to a 50 ohm load, and as such I used a function generator with an internal impedance of 50 ohms. Doing the correct calculations, I found the source and load impedance were matched to the attenuator at 50 ohms...

Hello, I am reading this article in wikipedia http://en.wikipedia.org/wiki/Attenuation_length about attenuation lengths and there is something I'm hoping someone here can explain to me. Lets say I have one small solid sphere and one big hollow sphere. And let's say I put the small sphere...

I am trying to understand why radio waves are not greatly attenuated by the atmosphere due to scattering or absorption? I have tried searching the internet and can't find any satisfactory answers. Please help. Oh and does this property somehow relate to why they are used to transmit information...

Do electric fields attenuate in space? If so what causes the attenuation?

Hello there. I've been struggling with this one for quite a long time now and decided to ask if any of you people could point out what I'm missing here. There are actually three problems which are related to each other. I managed to solve the first and the second one, but the third is where I...

Hi Would anyone help/advise me? I've done 2 experiments as part of my radiography degree. One was to investigate the effect of the ISL on a beam of x-ray photons. I could understand this, produced 2 graphs (Mean reading against distance (uGy) and Mean reading against 1/d squared) and wrote a...

Hello. Not sure if this is the right board to post. This is not homework. I am just self-teaching quantum physics as I read a book on the topic of X-ray Physics. It has about 30 chapters in total and so far I find myself having about 3 questions per chapter. Hope you guys don't mind me asking...

Consider a wave propagating in a medium with complex epsilon (e). Show that the ratio of decay length to wavelength is roughly Re(e)/Im(e) when the decay length is long compared to the wavelength. --- I could attempt this if I knew where to start... not much help, but could anyone...

Hello, I'm having some issues with plane waves propagating through a medium which is: - linear - spatially and temporally homogeneous - spatially non-dispersive - isotropic - temporally dispersive - passive I know that permittivity, permeability and the k-vector are complex in...

Homework Statement I see graphs for the total mass attenuation coefficient such as this all over the web:http://scientificsentence.net/Radiations/images/attenuation_coefficients.jpg However, I can't find data on the individual attenuation coefficients such as the photoelectric or Compton...

I am researching how photon intensity attenuates within matter and am a bit confused by what I have come across. Several sources state that the attenuation of photon intensity within matter is exponential (as a function of depth). The explanation is that photon interactions with electrons in...

Hello, Why does electromagnetic wave intensity attenuate exponentially with depth from its incident intensity in an object? Why is the relationship exponential? I just need a nudge in the right direction or more if you are willing. Thank you for any help!

Why do we call the attenuation coefficient LINEAR? I(x)=Ioexp[-µx] why µ is called linear?

Homework Statement Show from general considerations that the attenuation of power in the rectangular waveguide (TE10 mode propagating in z-direction) is: P(z)=P(0)exp(-2k''z) where k'' is the imaginary part of the wavevector in the phasor exp(j(wt-kz)) Homework Equations power is...

Homework Statement sphere r=1cm contains same density of H2O as surroundings with additional N=10^20 iodine atoms/cubic cm linear attenuation coeff (u) for water at 50keV = 0.2 /cm crosssection for interaction of 50kEV photon with iodine = c = 3.6x10^-22 /cm^2 a) calculate u for the...

Hi all, I can't figure this one out, but I'm sure I'm probably missing something simple. Here's the problem I'm having: From what I've been told in my SCUBA class (as well as from online article's and forums) light is attenuated in water in the order red->violet (red being attenuated first)...

Hi Forum, I am currently attempting to utilize http://bayes.wustl.edu/etj/articles/kramers-kronig.pdf" Unfortunately ... I have not been successful. I have tried for the past week and asked those around me. All help is appreciated. The equation is as follows: ( 1/c(w0) ) - ( 1/c(w) ) =...

Hi, I have been reading my textbook and online but I'm not sure if I understand. An EM wave attenuates in a conductor but not in a dielectric? If that is correct what does the impedance of a dielectric represent, since I thought impedance would be associated with an energy loss...

Hi, I'm having some trouble interpreting an equation. In Lamarsh's Introduction to Nuclear Engineering. The formulae for neutron attenuation is: I(x) = I_{0} exp(-\Sigma_{t} x I am given the formulae \frac{-dI}{I(x)} = \Sigma_{t} dx This formulae has been described as "the probability of a...

I know in scattering theory that a wave can be attenuated when it interacts with a dielectric sphere, it is partially scattered, partially absorbed. So, the scattering light has less flux density than was incident. However, if we use wave-particle duality then the same should be true for a...

It strikes me that this may well be fairly easy, but i can't quite get my head round the correct way to lay this problem out (at least in a mathematical sense). If you are considering a neutron flux onto a fully understood material, and you also know the neutron interaction cross section of...

During my A level physics class we were discussing the attenuation coefficient of x-rays and a question arose that I can't find an answer to anywhere. If someone could help answer what effect physical state (ie gas/liquid/solid ect) has on the attenuation coefficient of x-rays it would be much...

is the linear attenuation coefficient named like it is because it is linearly proportional (inversely) to the energy? I have to read off the coefficient from a graph I have. I have the value for a 2MeV photon, if I want the value for a 1MeV photon is it simply twice the 2MeV value? Reading off...

Homework Statement near-field distance attenuation follows an inverse cube law (1/d^3), while in the far-field it follows inverse law (1/d). Prove mathematically how we arrive at 60dB/decade from the inverse distance cube relation and 20dB/decade from the inverse distance relation...