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Questions tagged [light]

Photons and electromagnetic radiation, primarily in the human-visible range. For the chemical effects of light, use [photochemistry].

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Why is hydrogen peroxide kept in dark colored bottles?

Darker colors absorb more light than lighter colors. Light is favorable for the decomposition of hydrogen peroxide. Then shouldn't it be that the chemical is stored in white or lighter colored bottles,...
A Ghosh 's user avatar
2 votes
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How can glycerol make glass objects 'disappear'?

There's a famous experiment that uses glycerol (glycerin) to make glass objects 'disappear'. A glass object becomes nearly invisible when filled with glycerol and immersed in a container of the same ...
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2 votes
1 answer
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Ultraviolet Movie [closed]

What is the best material for a screen using an Ultra-violet light projector? I need a material/screen that can convert UV light into a visible light to best look like a normal movie theater screen ...
Justintimeforfun's user avatar
1 vote
1 answer
94 views

Is the energy difference between the 2s and 2p orbital smaller than the difference between 3s and 3p?

on this website (https://physics.nist.gov/PhysRefData/ASD/levels_form.html), you can look up atomic spectra. For example, if you query "Na I", you will see that the Level (cm^-1) for the ...
Theiserino's user avatar
1 vote
2 answers
93 views

Is light energy defined as work in thermodynamics?

Is Light/Radiant Energy considered Kinetic Energy or Potential Energy? I have started studying Thermodynamics, and the concept of internal energy was introduced, and defined as the sum of kinetic and ...
Nefeli 's user avatar
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Nutrients in translucent bottles/boxes

Nutrients e.g vitamin C, calcium etc are sensitive to light and that is the reason that major companies have juices and milks in boxes and opaque packages. But there are some companies that the recent ...
smith's user avatar
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Color of coordination compounds

My book(Page $259$ section $9.5.5$) says that the color mainly comes from absorption of light in the coordination compound: The color is complementary of the wavelength it absorbs , the wavelength ...
Razz's user avatar
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Why wavelength of Rubidium flame test(red violet) is more than Lithium(crimson red)

My teacher show this table from my book Here, you can see Red violet wavelength is more than Lithium, which is against order of visible light which increase according to acronym 'VIBGYOR' According ...
Shinnosuke's user avatar
2 votes
1 answer
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Diffraction Derivation- relating the angle between deflected ray and original

This relates to diffraction from objects with a periodic structure. I’m trying to relate the psi angle (diffracted angle) to the theta angle (angle between diffracted ray and the original non-...
Aurora's user avatar
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Emission Spectra Light Wavelength Deviations for Mercury

The Problem: Inconsistencies between the measured and true values of mercury's spectra light wavelengths emitted following a laboratory experiment. What I Know: The experiment conducted was viewing ...
Matt's user avatar
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Why does the same electron transition release photons of different frequencies for some elements?

Question: For elements in the same period with different numbers of valance electrons, why does the same electron transition release photons of different frequencies? Example: For valance electrons ...
Bryan351018's user avatar
1 vote
1 answer
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How are photons converted into thermal energy?

I know when light strikes an object it excites electrons into higher energy states. I know thermal energy is basically just a lot of atomic and molecular kinetic energy. Does the excitation of the ...
Jaccobw's user avatar
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1 answer
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Is a compound optically active if plane polarised light is deflected by an angle of n*(2π) angles? [closed]

Is a compound optically active if plane polarised light is deflected by an angle of n*(2π) angles(like 360°); as there won't be any deflection in the analyser of the polarimeter?
An_Elephant's user avatar
3 votes
0 answers
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Calculate frequency dose from different light intensities

The quantum yield for homolytic O-O cleavage of (CH$_3$)$_3$COOC(CH$_3$)$_3$ at $266$ nm is $0.21$. In one experiment, a pulsed laser of this wavelength was used to induce the formation of t-butoxyl ...
katara 's user avatar
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How does molecular structure contribute in the property of fluorescence?

Fluorescence is the property which is exhibited when electrons emit wavelength of light lower than the one they absorbed so does that mean we can make every molecule to become fluorescent? I wanted to ...
25 Simran Tiwari's user avatar
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Why Lambert's law does not hold for photoresistors?

Why don't photoresistors made of Si obey Lambert's cosine law? Is it related to the dark current of the photoresistor? I couldn't find any solution while searching the web.
Jun Seo-He's user avatar
3 votes
2 answers
116 views

A good lab demonstration of this particular optical transform pair?

At about 1:11 the video linked below shows what think is the optical Fourier transform of a sine wave as approximated by a saw blade. https://www.youtube.com/watch?v=jzmqeRp_tmk The set-up appears to ...
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How would I find what specific wavelength I need to measure for a specific chemical in spectrophotometry (calcium perchlorate)?

I am currently doing a research project, and for it, I would like to use a photospectrometer to find the concentration of Calcium Perchlorate in my sample solutions. My current method of data ...
Joseph Field's user avatar
3 votes
3 answers
627 views

How to Combine an Emission spectrum into a colour? [closed]

I am trying to wrap my head around the flame test, and for the most part, it is making sense. My question is their a way to figure out the colour of a flame of an unknown element given the emission ...
Yak's user avatar
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6 votes
2 answers
685 views

Why does calcium emit circularly polarized light?

One page 31 of Quantum Metrology, Imaging, and Communication by Simon, Jaeger and Sergienko, the authors state that: ... calcium has two electrons in its outermost, partially filled shell; these ...
User101's user avatar
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1 answer
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example of endothermic luminescence?

Someone posed an interesting question to me the other day: is all production of light accompanied by the generation of heat? I have found that the question as posed invites vague answers, so I thought ...
creillyucla's user avatar
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Can polarizing film reflect light instead of blocking light?

I was thinking about how to electorally switch glass between transparent and reflective just out of curiosity. I thought that maybe you could polarize the reflective glass in the vertical direction ...
user11937382's user avatar
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1 answer
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Fluorochrome (fluorescein) emission decay when linked to macromolecule

I measure the intensity and polarization of light emitted from a blood sample that contains excited fluorescein (experiment known as fluorescence polarization assay). The excitation is done, as usual, ...
nicolas005's user avatar
1 vote
0 answers
89 views

What is the amount of UV light required to make fluorophores glow and what is the minimum amount of electricity needed to achieve this?

So I have heard that fluorophores glow under UV light, so I was wondering what is the minimum amount of UV light needed to make the fluorophores glow and what would be the minimum amount of ...
Tsar Asterov XVII's user avatar
7 votes
1 answer
810 views

Does all fire only emit light on its outermost shell?

This question is about light emission, which may overlap with physics, but I am most interested in combustion and types of flame (incandescence, petrochemical fuel flames, nuclear reactions). Consider ...
dubious's user avatar
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1 answer
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Does electron emit photon when it moves? [closed]

When the photoelectric effect happens or blackbody radiation happens or when an electron jumps from a ground to an excited state, we say light is emitted by electron. Now, light is made up of photons. ...
Rider's user avatar
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1 answer
134 views

Which ceramic-like material is used in halogen MR16, GU5.3 and so on bulbs?

I hope this question belongs in here; I cannot think of any other better place to ask it. Which kind of material is used in dichroic halogen bulbs to attach the bulb itself to the reflector and keep ...
Pere's user avatar
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3 votes
1 answer
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Photodissociated iodine laser and population inversion

Iodine molecules ($\ce{I2}$) can absorb in the visible region and dissociate into $\ce{2 I^.}$ radicals. One of the I atoms is in ground electronic state $\mathrm{^2P_{3/2}}$ and the other I atom is ...
S R Maiti's user avatar
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-1 votes
1 answer
71 views

Relation of Energy required to change an orbit by electron of H atom with spectrum

We have the value for expression of line spectrum of hydrogen. $\Delta E = 13.6 \cdot Z^2 \cdot \left( \frac{1}{n_1^2} - \frac{1}{n_2^2} \right)$ Amount of energy required by electron to change its ...
Srijan's user avatar
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0 answers
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Excitation states of neon (or other gas) inside neon lights

I'm interested in the spectra of gas discharge tubes. Taking neon as an example, when I look up on NIST the spectra for neon, I find excitation states up to Ne IX. Where do I find/how do I work out ...
Beanman's user avatar
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How does Mars rover Curiosity's ChemCam's infrared laser produce a 100,000 K plasma plume (kT = 8.6 eV)?

Mars rover Curiosity's ChemCam uses a pulsed diode-pumped solid-state laser (DPSS) at 1064 nm to excite material on the surfaces of rocks up to 7 meters away, and a large aperture telescope to collect ...
uhoh's user avatar
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0 votes
1 answer
71 views

Actual color of colloids [closed]

I have read that the color of colloid depends upon the wavelength of light scattered by the dispersed phase and also in the sense in which the receiver receives the light. If all of this depends on ...
Arnav's user avatar
  • 23
1 vote
1 answer
594 views

Colour due to transmission and reflection

It makes sense to me that when looking through a sample (observer | sample | light), it should appear as the opposite of the light absorbed, but it does not make sense to me to expect the same when ...
peruca3d's user avatar
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11 votes
1 answer
2k views

How would you know if the light emitted is of one wavelength or if it is a mixture of two or more wavelengths? [closed]

I am just learning some chemistry after a long time without studying it and I have thought about something. Some copper compounds emit green light when heated to flame. So, I would like to know if it ...
sonlas10's user avatar
  • 241
1 vote
1 answer
494 views

Difference between flame test and ability to show photoelectric effect [closed]

My textbook says magnesium doesn't give flame test. But it also says that it is a good photoelectric material. Are both concepts using "visible" light to remove or excite electrons? What is ...
charan sahith's user avatar
0 votes
1 answer
331 views

Turning of a paddle wheel when exposed to light

So, we observe that in the discharge tube experiment when a very light paddle wheel is placed in the path of cathode rays, it starts turning due to the particle nature of the rays. My question is if ...
A_Singh7's user avatar
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2 votes
1 answer
57 views

Predicting color of a TMB derivative affected by peroxidase

The ELISA test on HIV works by verifying the presence of peroxidase within samples. The verification process is done through the enzymatic reaction that said peroxidase has on TMB (3,3',5,5'-...
Algorythmis's user avatar
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0 answers
49 views

Working principle of Fisher-Price Light Sketcher

I was just searching around in my store room and I found this Fisher-Price Light Sketcher. I am just amazed how the light from the pen draws on the board without even contact! I searched a lot but ...
serv0id's user avatar
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0 answers
271 views

What effect does the dye color have on the kinetics of a commercial lightstick?

According to thoughtco: If fluorescent dyes weren't put in glow sticks, you wouldn't see any light at all. This is because the energy produced is usually invisible ultraviolet light. Fluorescent dyes ...
Andrew Norfield's user avatar
16 votes
2 answers
2k views

How were x-ray diffraction patterns deciphered before computers?

I know the general idea behind x-ray crystallography is to take a high quality crystal and place it in the path of an x-ray beam. Areas of high electron density will diffract the beam and lead to ...
Joe's user avatar
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0 votes
0 answers
158 views

Absorption of UV Light and what color would be seen?

I am mathematically experimenting with different wavelengths of light that a fictional material would absorb. I thought of a material that absorbs a wavelength of $\pu{193 nm}$. This wavelength ...
Altraxian's user avatar
  • 111
9 votes
1 answer
2k views

What causes the blackening of light bulbs

in 1878, Thomas Edison (or rather William Joseph Hammer) added an anode in a light bulb in order to catch the flux of electrons coming out from the carbon filament and reduce the phenomenon of ...
Gigiux's user avatar
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2 votes
1 answer
269 views

What molecules are produced in carbon arc lamp and how do they produce light?

I am curious about the chemistry of the arc lamp (an indirectly for the incandescent bulbs) thus I would like to ask the following. It is a common understanding that the electrons pushed inside an ...
Gigiux's user avatar
  • 261
3 votes
2 answers
906 views

Cause of continuous spectral lines [closed]

We know different types of atoms have different spectral lines. But what exactly are the spectral lines representing? What causes white light to have a continuous spectra while other atoms show ...
NightKruger's user avatar
28 votes
2 answers
7k views

When a candle burns, why does the top of wick glow if bottom of flame is hottest?

Totally an elementary question. Staring at a candle, it appears that the bottom of the wick is dark whereas the top glows. However the bottom of the flame (the blue) is the hottest. Is the reason ...
ZAR's user avatar
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2 votes
0 answers
67 views

How do we determine the proportions of hydrogen to helium (to other elements) that make up the Sun given the absorption spectra?

I am reading about the composition of the Sun and how it is made up of mostly hydrogen (~90%) and helium (>10%) and other elements with much smaller quantities. The explains that different elements ...
Brian Blumberg's user avatar
0 votes
0 answers
37 views

Photochromism time of colour change

I know there are chemical pigments/dyes which produce an immediate reversible colour change in UV or direct sunlight. Is there a way to postpone the colour change so that it does not happen ...
Leja's user avatar
  • 1
1 vote
1 answer
396 views

How to assess sunscreen effective via blueprinting?

How do I assess the effectiveness of sunscreen creams by using the blueprinting process? I know blueprinting is done when something is sensitive to light and this may cause reactions to produce a ...
chemystery123's user avatar
2 votes
2 answers
108 views

Directional emission from molecules

This might be a silly question (probably is). When a molecule absorbs it has a transition dipole moment, a measure of how strongly a certain transition will interact with light will depend on how ...
Tomi's user avatar
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0 votes
2 answers
76 views

Process of transferring kinetic energy in regard to photons. [closed]

Now I know that temperature is the average kinetic energy of atoms, molecules and compounds. Photons increase the kinetic energy/temperature of molecules since photons are pure energy. Hence, wouldn't ...
Shane2020's user avatar