Questions tagged [visible-light]
Questions related to the perception and measurement of light (primarily in the visible range), its mathematical description, the reproduction of colors by different means, color combinations, etc. Please use the tag [electromagnetic-radiation] if you want to refer to the general form of light.
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Does anyone know the correct way to verify the color temperature of a given light source in a color booth and the equipment needed?
ie. spectroradiometer on the floor (constant distance) of the booth directly measuring the "observed" color temp emitted directly from the light source? is it more acurate to measure the ...
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Amateur Shower Thought Question About Time and Space
Apologize in advance if this is the wrong group. I often watch Netflix shows about blackholes explained in a nutshell or laymen’s terms.
I had a recent thought/scenario that may relate to some ...
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Lambertian surface and the luminous intensity
I am currently studying the basics of photometry to better understand the rendering equation of Kajiya. One thing I'm currently struggling with is Lambert's cosine law.
Let's go over the premises:
A ...
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Wavelength of "complementary colours"?
In physics/chemistry/the life sciences there's a common experimental method of determining the concentration of a sample using spectrophotometers. We can measure the absorbance of the sample at a ...
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Do the interference of two EM waves with the same frequency but different phase cause the EM waves to slow down?
So this question is inspired by the explanation of EM waves slowing down in a material through interference with waves produced by the material in response to the incoming EM wave. You can see ...
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Measuring the energy of a photon with $E = mc^2$ [closed]
Clearly light has energy because the photoelectric effect or photosynthesis would not work.
The formula $E = mc^2$ doesn’t work for measuring the lone energy of light as a massless particle, but it ...
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Conflicting lensmaker's equation representation
I keep finding these two conflicting forms of the lensmaker's equation. I understand that (n2-n1)/n1 is the same as (n-1) if referring to a lens in air, but I can not make sense of why the reciprical ...
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What happens to a photon leaving a grav well if it doesn't have the energy to get out of the well and the object it's leaving isn't a black hole?
Light exists with energy E = hf. That is supposed to be quantized and discrete but maybe "f" in the equation is continuous when not emitted specifically from an electron (moving through the ...
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How can gravity swallow light? [duplicate]
"In physics, gravity is a fundamental interaction which causes mutual attraction between all things that have mass"
"Light or visible light is electromagnetic radiation that has no mass&...
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Does the probability wave of a photon determine its color?
The wavelength or frequency of light determines its color. Photons seen as particles are said to have a frequency, determined by its energy, so I assume that 'is' the same color.
But being quantum ...
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Can a system of lenses or compound lens have a higher numerical aperture than a single element in the system?
I am attempting to create a simple Abbe condenser for a microscope, which typically consists of two converging lenses.
Ideally, I would like to achieve a numerical aperture for the condenser of ...
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Do there exist materials whose Opacity varies with temperature?
Do there exist materials whose Opacity varies with temperature?
E.g a Material that becomes more Opaque as it gets hotter?
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Is the Fourier Transform a reliable way to infer the physical phenomena producing an RF signal?
Consider the following thought experiments:
Scenario 1:
A person standing far away shines 3 light beams at you, each beam having a narrow spectral distribution centered around different frequencies F1,...
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Is it preferable to say $v$ is " image distance " than to say " image position " in spherical mirror formula?
I was going through spherical mirror formula $1/v + 1/u = 1/f$ where $u$, $v$ and $f$ are named as object distance, image distance and focal length respectively. But while using this equation we do ...
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Can I recover the physical wavelengths present in a light source from a time-series measurement of its amplitude?
Consider a mixture of different wavelengths being emitted from the same point (ex: a star). This light consists of a mixture of wavelengths and intensities at each wavelength. When measuring the ...
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Would the "FFT" of a light source be a reliable indicator of perceived color?
Paraphrasing from here:
A purely monochromatic 575nm wavelength light would be "perceived" as yellow, as would a light that has equal components in red and green (but no yellow). However, ...
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450nm peak absorption [closed]
I am looking for an oxide compound (metal oxide, or similar preferably inorganic) which shows light peak absorption at 450 nm. I have troubles in finding the right compound, as most of the oxides have ...
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Based on my calculations, we cannot see the Earth from the ISS. Obviously it's wrong. Why?
What started as a fun exercise really annoys me because I cannot see where I got it wrong.
I initially wanted to see how many photons hit a pixel of a camera on the ISS pointed at the Earth - but I ...
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Is reflected color not from the wavelength corresponding to that color?
I was reading through Josef Albers' interaction of color (a classical art color theory book), where he makes this point:
If I see a substance, or pigment of a particular color, doesn't that mean I'm ...
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Derivation of optical resolution
I'm trying to prove optical resolution formula from scratch and im having a hard time doing it. I dont know much about optics (im studying cosmology) and i need a detailed proof of optical resolution ...
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Is the speed of causality slower in water?
I've recently read that what most people learned to think of as the 'speed of light' is actually the 'speed of causality', and that light just happens to travel at that speed (through free-space.) I'...
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Number of fog droplets in the air
I have an issue with the official solution to this problem from BelPhO:
Visibility on the road is 100 m. Assuming that the diameter of a fog
droplet is 1 micron, estimate the concentration of fog ...
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How smooth must a surface be to produce specular reflection, and do Lunar boot prints meet this standard?
Question: How smooth must a surface be to produce specular reflection, and do Lunar boot prints meet this standard?
A recent post on Space Exploration asked why footprints on the moon displayed ...
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Does Law of Reflection gets violated?
I was curious as to why the "Law of Reflection" is only a law and not a principle. Are there any specific conditions or circumstances where it is not followed by chance? If so, how so?
Note: ...
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Why are diffuse white highlights on matte objects as bright as they are?
The reason we can see the color of objects is light rays undergo scattering in the subsurface of a material, and in their walk in the material lose some wavelengths, and finally exit at a random ...
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What is the connection between Ray (Geometric) optics and Electromagnetic theory optics in fiber optics?
I am currently reading about fiber optics and wave propagation in fiber optics and encountered the following part of Gerd Keiser's Book :
according to the diagram shown, its a general case when the ...
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Does our sense of color depend on frequency of source or the wavelength of light?
I was taught that the colors we see are results of the corresponding wavelength, but each wavelength also has a distinct frequency since speed of light is fixed for a specific medium (same goes for ...
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Do colours which are not visible to human eyes exist?
Are there any colours that our human eye cannot comprehend but other animals can see? The ability to see colours is the property of our eyes. For example an average dog would see less colours than us. ...
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Does two same light bulbs produce light of same frequency? [duplicate]
If they do, then why don't we observe interference in normal rooms? And if they don't have the same frequency then why is that so?
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Why do photons change direction when they pass through a optically denser/rarer object?
For example, during refraction, when photons pass through a glass slab, they change direction. Why does this happen? Is the reason for this not applicable when photons strike perpendicular to the ...
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What effect, if any, does dissipative absorption have on aurora borealis? Why don't we see more colors as a result?
According to wikipedia, the aurora borealis is primarily caused by charged particles from the solar wind being redirected to the poles by earth's magnetic field and slamming into the nitrogen and ...
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Is it possible to witness a rainbow while facing the sun?
We know that a rainbow occurs due to the refraction and reflection of light inside raindrops. We also know that inside spherical raindrops total internal reflection is not possible. So some light is ...
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Relativistic momentum for light
In special relativity,momentum $p$ is defined by $\gamma mv$ where $\gamma=\frac{1}{\sqrt{1-\frac{v^2}{c^2}}}$. Again,we are aware of the relation $E^2=(mc^2)^2+(pc)^2$. Now,the momentum of light is ...
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Why are no industrial diode lasers deep cooled?
Endurance lasers showed that a 633nm laser diode could lase as low as 621nm when cooled to almost -80C. The wavelength shift for diode lasers can surpass 0.3nm/‘C. From my limited experience ...
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What is the colour of an atom? [closed]
We know that when an electron jumps from shell to shell it produces light waves which produce the sensation of vision to our eyes. But can anything be said about the colour of an atom in particular. ...
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Wavelengths of light outside our solar system
The question might have been asked before. Our Sun's rays decompose into 7 elementary colors by using a prism or spectrometry. Can the the colors (their number and wave length in the spectrum ) be ...
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A object viewed from a red glass would appear red colour? [closed]
Original Question:
Explain, why in daylight an object appears red when seen through a red glass and black when seen through a blue glass?
My understanding according to what is given in my textbook ...
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Is unpolarized light necessarily a semi-classical phenomenon?
I'm aware that unpolarized light can be represented by a mixed state $\frac{1}{2}(|x\rangle\langle x| + |y\rangle\langle y |)$. It bothers me that in this framework, unpolarized light is a symptom of ...
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Does Color change happen under a prism? [duplicate]
I was watching this video.
It Showed that light ( green ) changes its color to red after incidence of light. I couldn't think of how this happens because light's color is dependent on frequency rather ...
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Attoseconds - generation of pulses of light for study of electron dynamics in matter
Related to the recent Nobel awarded for the generation of attosecond pulses of light I had a few doubts-
In high harmonic generation, why does the intensity of the emitted light drop, then stay ...
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How exactly does Ligo achieve complete destructive interference with just an interferometer?
Ligo works by destructively interfering light from a laser using an interferometer. Its said that no light enters the photo detector when all mirrors are the same distance. However,based on my ...
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How to define relevant emission spectrum lines? [closed]
I am building a tool which extracts the elemental composition of a light source using its emission spectrum. Therefor, I'm currently writing down the emission spectra of individual elements, but I'm ...
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Find total hours of sunlight in a day at a certain latitude [closed]
Im trying to find the total hours of sunlight on 15 August at a latitude of 54 o N.
Im using the Declination formula:
15 August = 226 days
And working through the ...
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What are some liquids with high ranges of refractive index with change in temperature?
I need to run an experiment on the effect of temperature on refractive index of a liquid, and in order to make the change most visible and have the lowest percent uncertainty I need the change in ...
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Is there a missing variable in the double slit experiment? [closed]
I've been reviewing the double slit experiment lately and I believe it is missing a few crucial things. Thickness of the wall is my primary focus. How could I add thickness into the equation? I'm ...
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Color temperature and space
I often think about the universe and lately about the color spectrum. so I wanted to ask how much the temperature of the body depends on the color. the hottest star I've found is 200,000 k and its ...
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Why do certain objects shine only in certain light?
I understand that wavelength is inversely proportional to index of refraction, which causes dispersion of light (red visible light is deflected less than purple), and total internal reflection.
Is ...
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Why is light emitted by an atom different to the light absorbed? Why do we not see absorbed light?
I’m confused about why we don’t see absorbed light. The way I understand it is if an atom absorbs a photon then the electrons move up to an energy level corresponding to the energy of the photon. The ...
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Rainbow formation [duplicate]
Please help me with my query regarding rainbow formation.
Many Books gave formation of only red and violet colour whereas middlemost colours are rising doubt.please check the following picture .My ...
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Are Transmission values for absorptive light filters proportional to Intensity?
Mostly filter rates are given in percent, but if I imagine that for example 10 photons hit an absorption filter with 50%, molecules are excited there and in the end only 5 get through while the other ...
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