Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: FuzzyUK on 13/10/2019 09:57:10
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Love or hate them, white LED street lights can aggravate some people due to the correlated color temperature (CCT) being high (4000K). Some people prefer warm white sources which are more like 2700K.
Cool white lights are derived from blue LED sources with a yellow phosphor coating. What happens when such light passes through a prism? Would it break down into rainbow colours or separate back into blue and yellow components?
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There are a number of representative spectra here (in colour, so it's not sterile numbers...):
- Sharp peak of blue light from the GaN LED
- A wider spectrum of red-green from the phosphor
https://thegreensunshineco.com/think-beyond-white-led-and-bulb-grow-lights-kelvin-and-color-temperature/
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There are all sorts of additional filters in the lens assemblies to minimise blue light hazard.
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There are all sorts of additional filters in the lens assemblies to minimise blue light hazard.
Possibly, but you can still see it so....
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True, but some of it has to be suppressed so as not to exceed the ICNIRP spectrophotometric limit for continuous exposure. The short term effect is loss of color discrimination, and the longterm can be color blindness and macular degeneration. It can be a problem if you are using "daylight" LEDs at high intensity in a workplace like an operating theatre, and SAD lights need careful attention to their actinic spectrum so that they do more good than harm.
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Obviously, the best "filter" to use is the phosphor.
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I'm no expert, but it's fascinating how those blue LED vibes mixed with yellow phosphor can create such a vibrant palette. It's like teamwork between colors! So, if you're into warm white vibes, it's like the blue and yellow components putting on a joint show. A bit of this, a bit of that ? making your street look like a masterpiece!
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@Grazzironi
Let's cut the Crap & get Straight to the point...
How much does This payout?
Per day/month/year?
Targets?
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Suddenly, a mischievous prism appears out of nowhere.
Instead, if you happen to be carrying around some ancient DVDs or CDs, you can use those as a diffraction grating.
I was interested in how good they are at telling the difference between say, a sodium and a mercury vapor lamp.
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I was interested in how good they are at telling the difference between say, a sodium and a mercury vapor lamp.
The village idiot had a problem. He had just bought two horses but was struggling to tell them apart. Someone suggested he measured their heights; and he was delighted to discover that the black one was two inches taller than the white one.
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Two philosophers were near a bar and discussing whether to go in or not.
Eventually they both came to the realization that the existence of the bar could have a profound meaning, in and of itself, perhaps related to the nature of existence itself.
After a few hours of pondering and careful consideration, one of the philosophers walked into the bar and proceeded to get seriously loaded. The other philosopher remained outside, pondering this occurrence. He might still be there.
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Under what conditions is a philosopher more use than a lump of rock?
I understand this has been set as an engineering exam question since about 6000 BC (Stonehenge Part 1 Honours) and has never been answered.
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How many philosophers does it take?
It only takes one, but first they have to confirm with a second philosopher that changing a lightbulb does not, in and of itself, challenge the existence of lightbulbs. Per se.
And thence, one or more lightbulbs must therefore exist.
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I'm not sure if this answer's Alan's question.
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Alas, it fell at the first hurdle.
0. We can take the existence of a mug as axiomatic, else the question is meaningless.
1. In order to place a mug on a stable horizontal surface, said surface must exist.
Therefore you need a lump of rock in order for the philosopher to contribute to the wellbeing of Mankind.
2. But you can also use a lump of rock to synchronise calendars (Stonehenge Foundation Course) - the essence of trade beyond the visual horizon.
3. Thus there are at least two more uses for a lump of rock than for a philosopher (proof by induction).
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Under what conditions is a philosopher more use than a lump of rock?
I understand this has been set as an engineering exam question since about 6000 BC (Stonehenge Part 1 Honours) and has never been answered.
I heard that an engineer gave "Testing bullet proof vests" as his answer.
The engineering dept gave him full marks, but the ethics cttee got upset.
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A philosophy of lightbulbs.
Once you understand that changing a lightbulb is an identity operation (modulo whether the bulb is working or not), then of course what the proof of existence theorem gives you (one or more lightbulbs), is a free monoid.
A regular expression. Philosophy has very little to do with it.
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i have Often, regretted my Speech.
Never my Silence!
(Xeno)