Questions tagged [light]

Electromagnetic radiation, specifically the range of wavelengths visible to humans ("visible light").

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Where can I get numerical data for the PAR (photosynthetically active radiation) curve?

I'm trying to do some rough figuring to calculating efficiencies of various light sources for growing plants. I'm hampered, however, by the lack of a curve to multiply by the spectrum of light ...
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101 views

Can low melatonin levels and/or LED lights cause or exacerbate macular degeneration?

I have two questions that may or may not be interconnected. My first question is: Does melatonin prevent macular degeneration? Could low melatonin levels (caused by blue-rich light exposure in the ...
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83 views

What amount of light energy is required to produce one O2 molecule? How about one molecule of NADPH?

I know that for each O2 molecule, a total of 8 photons are required (4 per photosystem). Would the amount of light energy required be E=hc/wavelength using 680 and 700? Or would the energy from the ...
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Most optically transparent muscle phantom?

I am trying to use Schlieren imaging techniques to visualize how a sound wave propagates through muscle tissue. In the past, when needing to experiment with muscle we would use an agar based muscle ...
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Are there any studies on the solar latitude limits of different plant species, beyond which they wouldn't thrive even with suitable weather?

Not sure whether this belongs here or in the Gardening & Landscaping StackExchange, but here goes... According to maps provided in the paper Present and future Köppen-Geiger climate ...
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What happens when pure chlorophyll A absorbs blue light?

When pure chlorophyll A is put in the presence of only blue light, what happens? My guess is that the extra energy is released as heat/kinetic energy, and then the electron has dropped to the lowest ...
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33 views

Are natural daylight lamps for Seasonal Affective Disorder just about the color temperature?

I've seen many expensive lamps made for people who have Seasonal Affective Disorder (SAD) and/or who live in regions where there isn't much daylight during the winter. I'm wondering if the benefit of ...
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69 views

Mobile carriers of Light reaction in higher plants

The hydrogen carrier PQ and the electron carrier PC are the mobile carriers in light reaction facilitating electron transfer from PS II to PS I during non-cyclic process. My question is - How do ...
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Does Rüppell's Griffon Vulture Have Greatest Vision Acuity? (Small Carrion Spotted at 10 km+?)

Synopsis: Some sources seem to imply the Rüppell's (griffon) vulture (Gyps rueppelli) can see objects at a distance in excess of 10 km -- roughly three times the ...
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What do I need to do to make a Reverse colorblind image?

As a 15 year suffering from moderate Protan colorblindness, I've wanted to find any advantages of colorblindness. I discovered there are Reverse colorblind tests, which only colorblind people are able ...
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131 views

What wavelengths of lights do plants need to grow?

So, I found a list of L.E.D.'s from Cree here (the company seems to be known for efficiency, they power most of the bicycle lights that I know of) is selling a line of lights designed for growing ...
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631 views

Is there a meaningful difference between direct and indirect light

I don't see a basis for a distinction, but I've heard several people distinguish between direct and indirect light for people, claiming that indirect light would be better in many cases. "Direct" ...
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Surface Power Density of Fluorescing Reaction

I am looking to find out what is the ballpark power density of a fluorescing PCR reaction using a SYBR Green or Taq Man dye might be. Is it on the order of $E_e=1mW/cm^2$, less or more? Any help of ...
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58 views

Dawn simulation - does color change affect waking up?

just curious. Are there any works or research results related to the influence of light color used for dawn simulation? I mean those wake-up lights which try to simulate dawn to make waking up better ...
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44 views

Is evolution the reason why water is colourless for our eyes?

Liquid water is transparent to most of the visible spectra, whereas it absorbs infrared. Similarly, the air is almost transparent to the visible spectra too. Could these be the reasons why our eyes ...
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488 views

Can light destroy auxin?

In my biology textbook, it says that plants grow towards light because auxin is laterally transferred from the light side to the shaded side, so more auxin stimulates growth and hence the plant bends ...
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29 views

Does iris color effect the amount of light that reaches photosensitive ganglion cells?

Does eye color (of iris) have any effect on the amount of light reaching retina cells and hence effect melatonin production?
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465 views

Can human perception differentiate between monochromatic and polychromatic light?

Maybe monochromatic is not the right word, what I mean is light consisting of a single wavelength (i.e. a spectral color) versus light composed of photons of multiple wavelengths (intermediate color). ...
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Spectroscopy on plant leafs

I'm trying to do spectroscopy readings on plants where I shoot electromagnetic waves and look at their signature/profile. I want to be able to do this at a distance, in the field and on live plants ...
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3k views

Why does vision gradually becomes dimmer in bright setting?

I don't know if this is only happens to me, but if I am in a well lit room and I stare at one point or just look at one area without moving my eyes around my vision in that specific light setting ...
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51 views

What are the effects of non-ultraviolet light radiation on DNA?

I am trying better understand the effects of varying the frequency of light on DNA, however, most of what comes up is "UV light" and how it is damaging to DNA (presumably by ionization). Have there ...
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100 views

How do PER/CRY complexes accumulate in the cytoplasm?

The Period/Cryptochrome (PER/CRY) complex is a heterodimer that transcriptionally regulates circadian rhythm. When it is phosphorylated, it is transported to the nucleus and it inhibits a ...
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37 views

Would blue light be effective to help average people when sunsets come much earlier in the day?

I know people with SAD (Seasonal Affective Disorder) benefit from blue light in the winter as night-time comes much earlier (in the UK, sunset is around 4pm in December, compared to 9pm in June). ...
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1answer
57 views

Fluorescent purple flowers?

Do some flowers fluoresce? Some deep purple Lobelias and larkspurs seem to glow and confuse my eyes in sunlight. It reminds me of those blue LED Christmas lights (they come in strings with other ...
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155 views

Do flies avoid infrared light?

If flies avoid IR light, many places can be kept free from flies using IR light. We see insect repellers in many restaurants, but they don't seem to work well. Can IR be a safe & effective ...
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34 views

Does cataract condition cause red film when sun is shining?

Since two years ago I have a red film in my field of vision when the sunlight (or a white spot) is at the border (or even lightly behind) of the vision field, the red color is especially obvious at ...
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What is the difference between GFP and rhodopsin?

GFP and Rhodopsin are both fluorescent proteins. What is the main difference between GFP and Rhodopsin in terms of how they work? I know that their excitation and emission wavelengths are different, ...
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117 views

Insects are attracted to light, what if the light is too bright?

Insects are known to approach light sources. I know that they use it as navigation tools, by maintaining a constant angle between their path and the light beam. However, if a light source is ...