Questions tagged [light]

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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 ...
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1answer
29 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'-...
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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 ...
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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 ...
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2answers
1k 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 ...
2
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1answer
104 views

What gives rise to the color of sapphires?

Here is what I know: Sapphires are composed primarily of $\ce{Al2O3}$ (in pure form colorless) as well as Fe and Ti (trace impurities responsible for the color). I know that the proportion and ...
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67 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 ...
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1answer
111 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 ...
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1answer
53 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 ...
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2answers
532 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 ...
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2answers
6k 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 ...
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0answers
34 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 ...
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32 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 ...
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1answer
128 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 ...
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2answers
57 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 ...
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2answers
53 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 ...
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1answer
75 views

How much heat is created by absorbent-type sunscreens?

I have a friend who claims her dermatologist told her than sunscreen was what was burning her skin. (I think it's much more likely that her rash/burn was either a sunburn, a skin reaction to some ...
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0answers
50 views

Is it possible to have a fully opaque 'switch glass'?

Current switch glass (smart glass) technology permits for a transparent glass to become semi-transparent, i.e., translucent. For my application, I was wondering if it was possible to make a 'smart ...
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1answer
332 views

Why objects usually don't exibit fluorescence/phosphorescence?

We learn in school that the color we perceive is determined by the light that is reflected back at us. Not all wavelengths of light reflect back at our eyes, some wavelengths are absorbed. I'm ...
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2answers
228 views

Will borosilicate glass absorb 808nm laser light?

Will borosilicate glass absorb 808nm laser light? If it instead refracts, then what is the refractive index? Also, will borosilicate reflect lower frequencies of light like those used in non contact ...