Uv Definition and 177 Threads

Hi, Does anyone know why the decay of hypochlorite/free chlorine in pool water due to UV light might show a logarithmic decay (natural log) as opposed to an exponential one? I did a chemistry experiment with scaled up concentrations of chlorine and cyanuric acid (scaled up 25x). Even in...

Xray in any matter have a slightly below one refraction index. Ultraviolet still have materials with above 1 refraction index. Where in the spectrum between them does >1 index cease to be possible, and what is the nature of this threshold?

Hi everybody, I'm involved with a project that wants to use PVC pipes as gutters for a rainwater harvesting system. The water is intended for human consumption (after it passes through clay filters to take care of biological contaminants). I've been looking at PVC degradation under UV and...

Ok thanks for the responses to my other question; I think I now have it. I have a follow up question – that is almost on the same topic (but not quite) The complete spectrum (arund 200nm to 380nm) of UV light is absorbed by some plastics?? Elections will be moved to a more energetic orbital...

Infrared heats a body but UV heats less! If we consider two bodies of indentical properties (and temperature) and we apply radiation on them with different EM wave ,One with Infrared and the other with UV ray,we find that the body exposed by IR has more temperature increase with respect to...

I have a 100watt xenon lamp , the UV component comprises of 5-6% of the total spectrum emitted by the xenon lamp . How do I calculate at what power is the UV light emitted ? Is the whole spectrum being emitted at 100 W or is the power distributed through the spectrum? How is this...

Hey all, I wake up with morning to find an email from spaceweather which says: EARTH-DIRECTED FLARE: Active sunspot 1401 erupted today, Jan. 19th, for more than an hour around 16:00 UT. The long-duration blast produced an M3-class solar flare and a CME that appears to be heading toward...

I have a 300 W UV bulb (http://www.bulborama.com/300R-E27-ULTRA-VITALUX-OSRAM-SUN-LAMP-TANNING-BULB-230-VOLTS-300-WATTS-p711.html). I am trying to determine the W/m2 without buying a $3k radiometer. I will be using this bulb to irradiate cells during a protection experiment. Thank you...

Homework Statement function inside is (x+y)^2 * sin(x^2 - y^2) R is the triangular region w/ vertices (0,0) , (0,2) , (1,1) x = (u+v)/2 y = (v-u)/2 What are the correct limits ?? The Attempt at a Solution Also, when plugging in x and y in the function, i ended up getting...

As a quick heads up, I'm buried over my head in an imager project, and the portion that has given me the most headache is the UV source. Essentially, I need the source to make nice little 13 micron dots in the 405 nm range. I've been assured by a pair of vendors that this is an easy matter...

According to my understand of what makes something transparent, it's because a given wavelength of light doesn't have sufficient energy to raise the electrons in a material to a higher energy level, so the photons are not absorbed and continue on. This explains why glass is transparent for...

Many years having passed since I last looked at an electrical circuit, I been asked to design an electrical circuit at work. We make tonic water, and the idea is to create a holder for bottles with a built-in UV light rigging. Due to the relative efficiency, robustness, cheapness etc, I am...

What theories of quantum gravity are currently UV complete?

Hi, Is there a such mirror which can reflects a UV laser (~190nm wavelength) with Reflectance greater than 95% and also invisible laser (not necessarily in a high Reflectance)? Thanks

Hello! could you help me with this? I´m from biology field and have some difficulties with the following calculation: I want to estimate how much mor UV is coming from a mercury short arc lamp of a fluorescence microscop compared with the sun UV, so that I use the right eye protection for...

Hi, I'm looking for papers and general or specific information about the topic Astronomy in UV and X-ray Spectrum. Other than Wikipedia and Google sources, I would be interested in understanding the optical spectrum range and its limits, with respect to the materials used in this astronomy...

Hello, I was wondering what fraction of the energy delivered by the sun is due to UV-radiation. For example, when I have a solar panel which "catches" 1kJ of solar energy. What will happen if there would be no UV frequencies in the solar spectrum? How many percent less energy will I capture...

Hi all, This is about installing UV lamps so I guess I should post this in the Electrical sub-forum. I am actually looking for a short but power UV lamps with the purpose of polymerization of chemical monomer. My original search parameter of lamps: -Able to hit up to 25mW/cm2. -Total...

Please teach me this: Why point particle interaction(QTF theory) has UV divergences,but string interaction does not have UV divergences.Because I think that calculating the probability amplitude of a process,we must sum(or integrate) over all possible value of momentum.So how we avoid the UV...

Which color is the best reflector of UV light? In scientific-popular movie ``The future is wild`` they believe that high altitude gooses should have beauty blue color http://www.thefutureiswild.com/futurassic.asp?level1id=4&level2id=11&level3id=46&level4id=70" to protect themself from harmful...

Hi, Imagine UV unit used for disinfection of potable water. The turbidity of water is ~0.2 NTU – measured in lab. However at times the on-line analyser for the unit reads above detection limit (>30 NTU) – due to air presence – lots of small air bubbles which clear if sample is left for ~15...

Hi! A classic example in order to demonstrate the Photoelectric Effect, is to charge a metal plate (by electrons) connected to an electroscope and observe how the charge decreases when lightning by UV light. When put a pane of glass in front of the metal plate, we observe that the charge...

Is there any evidence that M-theory (where M may stand for Matrix, Membrane, or whatever ...) could be UV finite? I am not asking for a proof (because I know there is none), but only for a piece of evidence or an argument which is more than a pure wish. If you know about such evidence, an...

I want to keep all the species and radiation from plasma but not UV. Is there a way to design plasma source in a way that there will be no UV coming out?

Hi all, For a while now I have been searching for an electrically conductive material which is also UV transparent. Anyone here has come across such a material (solid or liquid) ? Thanks :)

I keep seeing references to UV and IR in references to string theory and quantum gravity. This seems to come up in discussions of renormalization especially. Can someone please explicitly explain the term? Google doesn't seem to help here. There are way too many references. I have tried...

Hi! I did a laboration on detecting different wavelenght from a UV-c light tube and the electrometer detected some activity from the Monochromator in the area of visible light (400nm-700nm). I would like to know if this has something to do with the quality of the light tube? Or does something...

can ZETA REGULARIZATION avoid all the UV divergences ?? i found a paper http://vixra.org/pdf/1005.0071v1.pdf so using Zeta regularization i can regularize all the integrals by replacing divergent integrals by divergent sums and applying zeta regularization algorithm to get only FINITE results...

Hi In UV spectrscopy, is the definition of absorbance (A = ecl) derived from the definition of transmission (T = It/Io) where It is the transmitted light and Io is the incident light, or is the definition of transmission defined from absorbance. Also A = -log(T) and T = 10^-A = 10-ecl...

Hi What units does incident light have in UV spec? Is it joules? Transmission is defined as transmitted light / incident light so any units of light simply cancel out to give a unitless number. I presume the original units were joules as light is EMR? Perhaps its more complicated than that...

what is the absorption spectrum in UV radiations of iron?

I am designing a UV disinfection unit think: http://www.wedeco.com.au/www.australianultraviolet.com.au/animation2.gif I need to ensure an internal intensity/dose of 410 J/m.sq to all waters that pass though. (to comply with WHO guidelines) I am aware of The Beer-Lambert Law but will...

I believe many of us have seen this in CSI, or Dexter or some other TV show or something. Some guy spraying somekind of liquid onto a surface and pointing some UV light on it. The bloodspatter shows up, even though you could not see it without this method. So my question would be what's the...

It's simply common sense that looking directly into the sun is a bad thing, but what about with your eyes shut? I'm unsure if the UV rays can penetrate the eyelid, or at least if they can, if a significant percentage of the rays get through. Is it a factor to consider when tanning for over an...

I was focusing sunlight on my Magnifying Glass & was amazed how powerful the beam was. Even on a dark object it was far too bright to look at. I wanted to try & cook & marshmallow with it. But would that be dangerous because of uv rays? Is it just visible light that focuses through the glass or...

i was recently reading about uv absorbance, and i understand why species such as the phenoxide ion and aniline absorb uv radiation at longer radiation and with more efficiency than their protonated counterparts. i have spent long hours, however, trying to figure out why a benzoate ion might...

I was watching two small lectures on youtube about black body radiation, they are interesting but I am questioning some of the information they provide : http://www.youtube.com/view_play_list?p=254B23CEE44ABE58&playnext=1&playnext_from=PL&v=6tikmVfrQrk...

is it possible to have a material block high wavelength waves but not low length waves? Gamma rays can pass through objects that visible light cannot. Any thoughts? I was thinking a certain bandgap?

Homework Statement A very short pulse UV laser is used to liberate a number of electrons from the negative plate in the arrangement in (i) above. The electrons drift towards the positive plate under the influence of the electric field over a time scale much longer than the laser pulse...

I'm looking for a cheap solar cell for an experiment that we're doing on different sunblock lotions. Will a clear sunblock lotion (say spf 50) affect the ability for a common solar cell to produce electricity? If the answer to the first question is no, is there a solar cell that does use...

http://www.alexandme.com/ sells uv protected swim clothes for a 4 times the price. All I could see is swim suits which are covering more body parts. Is the material different?

Hi, I'm doing an investigation into the absorbance of UV light by glass of varying thickness (constant density and standard type of glass) for an assigment. However, we're not actually supposed to carry out the investigation due to time constraints, so we're meant to make up the numbers...

which color is better at blocking UV rays? my take on it is this analogy: you have a room with one window, cover it with a fabric curtain that is black the room becomes very dark. cover it with that same curtain except white and the room is somewhat brighter. less light = less UV rays a...

http://www.oreck.com/upright-vacuum-cleaners/oreck_halo.cfm With a typical UV exposure time of probably less than a second, does this make sense? In the video below, they make the argument that after six passes, we see signficaint reductions in bacteria levels. So I guess one could consider...

Dear forum members, I would like to ask some help regarding irradiance calculation. I am a high school student doing a project in biology in which I expose drosophila m. (fruit flies) to UVA radiation and I would like to mention in my paper the actual dose that was used. I know that... UV...

question is why speak about IR (short momentum) and UV (short distances) divergences ? in fact if we define \epsilon = 1/\Lambda then both integrals \int_{\epsilon}^{\infty}x^{-k}dx and the \int_{0}^{\Lambda}x^{k-2}dx have the same rate of divergence \Lambda ^{k-1} as...

Snorkeling in the Red Sea, I noticed fish that were near the edge of my purple-range. They were small--perhaps 3-5 inches. Looking at guides I would say they were angelfish or anthias, but surely there are marine biologists who know exactly what these were. I have see other purple fish, these...

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:

Zeta regularization for UV divergences ?? I know that zeta regularization makes sense but is this paper correct ? http://arxiv.org/ftp/arxiv/papers/0906/0906.2418.pdf watched on arxiv by a chance, there are 2 sections the 'divergent integral' treatment by using zeta regularization is on...

If M is a monoid and u,v\in M, and uv = 1, do we know vu = 1? Can someone prove this or provide a counterexample? I tried to come up with one (a counterexample, that is) using 2 x 2 matrices but was unsuccessful.