Uv Definition and 185 Threads

Hi everyone, I suffer from Delayed Sleep Phase Disorder: https://en.wikipedia.org/wiki/Delayed_sleep_phase_disorder I've been taking sleeping pills for it for years (without them, I'd never be up in time for work) but have recently become concerned about adverse consequences of long-term use...

I'm trying to understand the effect on a metal alloy of UV light (diode or laser) pulsing at about 1MHz. I am assuming that the stirring of atoms will generate heat, possibly moving the alloy to its eutectic point (depending on the alloy) and in particular to atomic motion. Can anyone...

Consider the one loop corrections to the propagator and the vertex in ##\phi^4## theory in the attachment The former gives an integral representation proportional to ##\int d^4 k/k^2## in ##4## dimensions while the latter gives a representation ##\int d^4 k/k^2 (k+p)^2## where ##p## is the...

loop quantum gravity and loop quantum cosmology gravity becomes weaker then repulsive instead of stronger, towards the Planck regime, due to the onset of quantum effects. gravity near Planck energies and densities, LQG/LQC becomes repulsive. at the inflection point where LQG gravity strength...

Hi,I have a question when I was reading this website: http://www.webexhibits.org/causesofcolor/7F.html It explains how melanin works to protect us against UV light. From high school physics course we know that black absorbs light while white reflects. I understand when melanin accumulates,more...

Hi everybody! I was hoping I could get some insight on how to calculate the energy of uva and uvb radiation at elevation levels of 0m in equatorial regions and at a lattitude of 35° N at 4500m in watts per square meter. Specifically, light in the range of 300-420nm. Any help would be...

i am conducting my thesis and i am adsorbing phenol with activated carbon, my original solution is clear(colorless) but when i cntact it with the adsorbent and filter it after a certain time, it became colored of some very pale yellow. i am just wondering will the color change have an effect on...

Hi all, I have a few questions in regards to UV light (or any other light on the spectrum) and if anyone could point me in the direction of any textbook or online resource to read up it would be appreciated. I would like to know how you can figure out the amount of energy required to produce...

Hello everyone, I own a handheld UV lamp, it looks like this: I've been using it for my hobby interests, like finding out what luminescent materials at home etc. Recently a friend of mine told me that germ killing uv light could be dangerous to sensitive retina parts. I know that this...

If only 14% of the total solar emission is in the UV region, why is ozone depletion a cause for concern. Considering that only a small fraction of the sun's total radiation reaches earth.

Hello, I have a handheld UV mercury vapor lamp, which, when working, leaks some visible light around violet wavelengths. My question is whether it is possible to block violet light but let the UV light using some kind of colored transparent sheets. Thank you..

HI Guys .. I really need some help on this ... I need to manufacture(mix) a liquid that 'displays' as UV light if that's the correct term. any ideas where I could start ? I have limited chemicals knowledge :/

Hi everyone, searching on the web about how the fluorescent lamps work, I cannot understand if the UV is emitted by the noble gas or the mercury. For what I understand, both of them ionize, and the UV light is emitted after the collision of the electrons with the atoms, but I would like to...

Is solar uv completely blocked from reaching Earth or do we just need more sensitive uv detectors to make ground-based observations? In particular of the uv wavelengths corresponding to hydrogen Lyman series lines.

The question is in the title: is it possible for a theory to be both UV and IR stable? And concrete models would be much appreciated!

For a photopolymer, the heuristic goes that longer wavelengths of UV light penetrate deeper than shorter wavelengths of UV light. For example, the UVA spectrum penetrates more deeply into the photopolymer than the UVC spectrum. What is the best way for this to be explained?

For a photopolymer, the heuristic goes that longer wavelengths of UV light penetrate deeper than shorter wavelengths of UV light. For example, the UVA spectrum penetrates more deeply into the photopolymer than the UVC spectrum. What is the best way for this to be explained?

Hi I am looking to repaint my windows. I've noticed that black paint lasts very well generally. I don't really want my windows black. Is there anyway I can reduce uv damage to the binder in the paint by adding some UV blocking colour? I've googled UV blocking pigments but it doesn't seem to come...

Hi guys, please can you kindly help me. I am getting an absorbance of over 6.0Abs for my experiment. However, when I am reading posts they mention that an absorbance above 1 is not reliable. Please can you explain so that I can understand. Thanks

I am 67 and three years ago I was diagnosed with uv aggravated eczema. The doctors recommend wearing close woven fabrics to block uv but i find they don't really cut the mustard. my idea is to sew a lining into the back (where most irritation occurs) of a lightweight jacket and insert a sheet of...

When I observe the UV light emitted, I can literally see the millions of photons appear and die within milliseconds, but nobody else around me can. When I observe IF light sources and transmitters in low light, it is the same characteristic, except there only appears to be to photon sources, and...

this might be kind of a weird question lol but according to forums on tortoises and other reptiles, ceramic heat emitters (a piece of ceramic heated to about 200 degrees id say) actually emit a UV radiation... is this true? where does the radiation come from? is it black body radiation...

Practical question: Will placing a clear UV filter over a magnifying lens inhibit the ability of that lens to focus sunlight to the degree necessary to produce fire? I have a window with several "bullseye glass" panels in my home and have noticed that when the bright winter sun passes through...

UV catastrophe didn't occur because em are quantized.. so the higher frequency modes were not there. In vacuum.. if you compute the contribution of the em modes, it is 120 magnitude greater than observed.. the mystery is why it is not and they theorize it is just canceled out. But why didn't...

Hello,I'm new to the physics forum.I have a question regarding fluorescence,and I didn't know where to post it exactly,so I decided to do it here... I like growing plants,and am forced to grow them under artificial lights during winter.I am always on the lookout for more efficient lights,that...

Homework Statement Your molecular biology lab studies proteins, and you're frustrated because your microscopes can't quite resolve crystallized proteins. A sales rep touts the advantages of an expensive microscope using 200-nm ultraviolet light, saying you'll be able to resolve structures less...

I understand that asymptotically free theories must be based on UV fixed points rather than IR ones, because the RG flow goes into rather than out of an IR fixed point, so an asymptotically free theory based on an IR fixed point is trivial at low energies. But at higher energies the coupling...

So I was reading that Osmium will break down into a poison oxide gas if it is heated in the presence of air. If Osmium is blended into an alloy will that eliminate its ability to oxidize in such a manner. I have been looking at Osmium as a UV reflective material but poison gas break down is...

What exactly did Max Planck assert regarding the discrete quantum nature of energy that was so significant to the observations obtained of black bodies, which contradicted the classical predictions of the time? i.e. the UV catastrophe? My overall understanding is flawed I wonder if you...

Hello! First post here, so hopefully I'm not doing anything wrong. I've hit a dead end with an experiment and could use some additional perspective. I'm in need of material for a 100 mL round boiling flask that has good transparency down to about 140 -180 nm. I originally considered Type 214...

A new type of energy storage described which uses quantum way to store energy. ''Battenice''. http://techon.nikkeibp.co.jp/english/NEWS_EN/20140224/335902/ How exactly new energy levels could form under UV light? What do the mean?

Is M-Theory the only possible UV completion of Supergravity?

Hello all, I am looking for easy to obtain materials, preferably in powder form, with good absorbance at 808nm, 365 nm and 404 nm each (either one material for each wavelength or one for all three).However I can't seem to find absorbance charts. Does anyone have any idea either on which...

Hello all, Long time no see. I am hoping to find someone with knowledge of light output (in particular UVA output) of fluorescent tube lights. I have 2 questions: -Should I expect the light output of a 20 watt CFL bulb and a 20 watt 2 foot long fluorescent tube to be the same, or...

Ok, so I have a 405nm laser pointer (bluish purple/uv). Had a few miscellaneous glass objects and was shining it through them when I noted a light green line in the glass that it shone through. One of the objects is a sphere of alexandrite, so I assumed that it was a property of the...

Hi! I would like to ask if there is possible to find out the photon flux emitted by a uv source having only the intensity/wavelength spectrum of the source? pp

I received a handout at university that I believe could be erroneous. It states. "IR radiation has a higher potential to warm objects than UV light. Does IR therefore have a higher energy level?" It refers to E = hf Note it mentions 'UV light' but 'IR radiation', not written by a...

I recently repaired some damage on my car, which isn't quite done - I still have to scrape the runs. However, the paint is a significantly different shade from the rest of the car. I asked to have the codes matched, so I assume it's because of fading. Is it possible to mask off the old...

Hi, I am working on my thesis which is going to be uv instrumentation using photodiodes. I had in mind to extract the UV from the whole solar spectrum at sea level. I know that the UV band is narrow compared to visible and IR. I also wish to experiment with the various components like...

Hello! At work we have an UV aging test chamber that produces around 140 W.m^-2 UVA 15 W.m^-2 UVB and less then 1 W.m^-2 of UVC. The chamber is big, we have to go in and out to collect the items. Is it possible to have ozone formation or other harmful gases inside the chamber?

If the sun is producing plasma on a large scale on a regular basis, isn't it then true on a smaller scale that we could use the UV Rays of the sun to produce plasma by smashing two magnified rays and liquid hydrogen together in a high speed chamber? The result would be hot plasma that could be...

Hello. I was curious on how the content of an UV-eraseable EPROM chip degrade when it's being erased. So, i put a picture into a chip from a TV test signal generator (M27C512), powered it up, and put an UV erasing lamp next to it, expecting pixels to go pop... pop... pop pop popopopopop or...

When welder are working on pipelines, they use filters that block out UV light. Why is this precaution necessary? Does the question mean that they wear some type of glasses to help protect their eyes? or does the filter block UV light from going into the pipeline? This is what I...

I think i have looked at like 20-30 web pages, and i can't find a simple step-by-step explanation of the operational principle. I know, that when a rare gas like Helium, relaxes from an excited state two characteristic emission lines occur. But how do you excite the gas in the first place...

My general question is: can high energy photons convert into many lower energy photons? Could the reverse reaction occur spontaneously? Let's say we have a single photon that was emitted from a distant supernova. We detect it here on Earth. The photon hasn't converted into multiple lower...

Simple question will UV glue that is supposed to be dried under a UV light dry or harden if taken and placed in direct sunlight? John

Hi There Am training to be science teacher at secondary school. A few issues have arisen for me lately and would like clarification: Issue 1: have been studying electromagnetic spectrum with my year 10 class. We have discussed Herschel's experiment in which he discovered IR radiation by...

I recently purchased two strings of RGB LED lights, the kind you can set to all sorts of colors by combining red, green and blue in various amounts. Unfortunately, I strongly suspect that the blue and green led-pieces produce light that is contaminated with UV. Various UV-reactive things in...

Or light rays for that matter. Where does the window open in the atmosphere on the em spectrum, UV? Why is that?

Using an EPROM as a UV detector. I was planning to make a UV meter using an EPROM. The idea was that ultraviolet light erases an EPROM. When a fully programmed EPROM (all zero's) is exposed to uv light I should clearly see the number of bits (one's) increasing. So I have built a small...