Color Definition and 494 Threads

I want to illustrate what the color mixing that is done with a tv screen is all about, and how we can generate the appearance of color using primary colors, even though we don't actually generate any light of the color that we perceive. Consider beginning with a tungsten filament with a...

In the Dark Ages, resistor values were indicated by colored bans, and we all had to memorize the code. (This was back when they were bigger than a speck of dust) My question is - why colored bands? Caps have numbers printed on them (as do some resistors). Why fool with bands if you can just...

Each type of cell responds to light with wavelengths in a certain range. The distinct ranges center around yellowish red, green, and bluish violet, respectively. A "response" from a receptor cell is some neural signal to the brain. The combination of the responses of all our receptor cells...

I am not sure what the context of the question is. I am thinking this question is about light bulb emitting different colour at different temperature. The higher the temperature, the lower the wavelength hence the higher the energy emitted by the bulb so the energy consumption will also be...

This is the Question: It's from the book: Concepts of Physics by Dr. H C Verma. The common observation is off course that a red light would appear red even when viewed from under the water (for eg in a swimming pool). But, in the same book, it's been written that colour depends on wavelength...

Taking into account the Rayleigh scattering phenomenon, assuming that the atmosphere is 1 bar, how would the light from the G2V-type star interact with this kind of environment? Could the colour of the sky even alter despite the fact that there is a significant amount of sulfur dioxide in the...

I don't have a color printer, so the standard blue used by Adobe for fillable forms don't come out well. Going to Edit>Text , Adobe gives me an ad to upgrade to Pro. Various internet sites tell me to go to form field settings or to Preferences, but I cannot find a path that will get me there. Is...

Hi there, i just started to learn mechanic about few years ago and I wanted to know about car smoke color, What does the smoke color means in disel car and petrol car, Black,Blue,Grey,White smoke color?

Bear with me this will be long, but everything here I feel is necessary to understand the context. I recently used a crt at varying refresh rates and noticed a few things that has made me question how the brain perceives colors on a display. First, is that my crt appears to have more color...

Gooood Morning I was traveling with my son and he noted the rainbow out the window and asked why we see only half. I informed him that the earth blocks the other half and if we were in an airplane, we could see the entire circle. Set that aside. When we look at the electromagnetic spectrum...

Aromatic amines having a brown color

Basically, microsoft excel always has white background cells, and I'd like it to be a different color. Here's what I've tried: I configured the below registry value in my Windows 11 user profile to change the default window color from 255 255 255 (i.e. white) to 192 192 192 (i.e. a not so...

If I place a mirror on the ground facing upward, what color will those who observe it from space see?

I have been doing some 3D computer graphics modelling and I have observed a phenomenon I cannot find anything about. I am using Blender (free 3D program). I am also using "Just Color Picker" which is a free Windows tool that let's you check the hue/saturation/value (HSV) for any color on your...

This is the color of the metal bucket when it's not hot. But whenever it is hot, the red changes to dark, and then back to red again when it is not hot. See the following youtube where I just threw the fake money at the bucket (see background below). Can you explain how the phenomenon work...

Is it possible to get the photoelectric effect in red color frequency?

I have a little question about Rayleigh scattering: I know that Rayleigh cross section is proportional to the inverse of the fourth power of the wavelength of the incident light and that it is so even the intensity of the scattered beam of light, now: 1. What is the color of the sky due to...

For the illuminant A for the illuminant B Did I got them correct? Thank you

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I will tell my research that i have done earlier here. CMYK is used for print pieces like brochurers and business cards. For RGB we need to start on black paper but we can't add light until we reach white because light can't be painted on surface, what does this bold content means to say? in a...

I will tell my research that i have done earlier here. CMYK is used for print pieces like brochurers and business cards. For RGB we need to start on black paper but we can't add light until we reach white because light can't be painted on surface, what does this bold content means to say? in a...

I have not noticed anything in common between all things that are the same color. It must be something on the atomic level but if I look at the periodic table I see no pattern in how things behave and what their color is. So how can the sun be the same color as a highlighter and plastic the same...

Hello everybody, I would love some help on the following; I have a spectral date (As image 1 below) formed by the wavelength, refraction index and the absorption coefficient. Is there any way to relate this spectral date to a dominant wavelength? or in a few words extract the color from this...

Hello! PS. This is not a Homework question, I am asking about a concept. I am a Physics teacher from Brazil and last week one of the biggest Engineer universities here applied its entrance exam. However, a lot of teachers (including me) don't agree with one of the answers. Can you guys help...

I am from Europe and mainly do engineering here but now I have a new project for a machine that is going to be installed on a wind-farm outside of New York. We have a very specific customer spec that specifies the wire colors that we have to use in all the power cables. The spec says the...

There are 12 triangles (picture). We color each side of the triangle in red, green or blue. Among the $3^{24}$ possible colorings, how many have the property that every triangle has one edge of each color?

If different eyes appeared let say to less sun or an accidental mutation, has it become subject to selection of individuals like eugenism or due to modern gene technology nowadays ?

Given values : - Distance between the slit source and the screen L - d1,d2 The problem is to detemine the color of the two lights

As far as I know, the sky is blue because of the natural vibration of the molecules of the air enter in a ressonance with the ultraviolet spectrum, so when the sun light hits the air molecules the scattering occours more on the ultraviolet part, but blue part of the visible spectrum is more...

I use the GMail web interface, in Firefox, for all my email needs. 
 I frequently change the color of text that I quoted from the Sender in my GMail replies. 
 Example: 
 Hi, 
 You wrote, ". . . a;sdkfjasl;fkjasl;kfj . . . ," 
 and I just want to...

I was reading this article about the a replica of the famous Hope Diamond and its antecedents: https://www.nytimes.com/2020/11/28/style/hope-diamond-story-smithsonian-copy.html This part seems to say that the color is to be simulated by a coating: It would seem to me that the proper attenuation...

Physicist and color scientist. Experience at Kodak and Pantone. Taught physics at community colleges in retirement.

Hi, I am looking at videos of spark gaps and see that there are different colors of plasma. I really should've been a physicist because this may be fundamental, but I'm wondering what the different colors mean? I have seen purple and white. My guess is that white is a higher energy discharge...

Isn't it $$\color{red}x\color{black}y$$

When you look at the following image through a prism with the apex (thinner portion) pointed towards the left or the right, why do you see magenta on one side and green and black on the other? Keep in mind that the spectrum is reversed.

My 50 year old science book says, black is absence of all color. Do any books still say, black is absence of all color? I looked online for 30 minutes no where say, black is absence of all color. NOW everything says, Black is the darkest color. Why the change in books? If black is not a...

We know ##\lambda_{blue} < \lambda_{red}## so citing the formula above (in the relevant equations) it's apparent that blue light is scattered more than red light. But presumably this would hold for ##\theta = 0## as well but when we look at the sun head on we don't see blue, we see red/orange...

Ferroin is a redox indicator. It is the complexation of phenanthroline and iron. In its reduced state the Fe (II) - phenanthroline complex is red and in its oxidized state the Fe(III)- phenanthroline complex is blue. I am trying to understand in the context of d-d orbital transitions why this is...

I'm wondering if the outside color has an influence on the thermal depletion of things such as a thermos, a wall, etc. Assuming, obviously, there's no sunlight hitting on them. It certainly has, but what difference percentage can we typically expect for example for bottles such as the ones on...

I am working on a problem which asks for the B-V magnitude of a star cluster given N stars of type F and M stars of type K. I have values for B-V for both stellar types. I've derived a general formula for computing the magnitude of the cluster from the magnitudes of each star type, which...

Hi, I have been taught that quarks don't exist individually on their own, as they has with be with at least another antiquark to form a colorless state. But in the quark-gluon plasma, do we have individual quarks in a color state or do they still, somehow, are in a color-neutral state? Thanks!

I'm creating a type of image processing software and I have a need to get the color that best represents text once I have identified the pixels in a region of text. I've tried using simple strategies like "averaging" the pixels or taking the most common pixel, but these produces bad results An...

Today I read about a seemingly new way of using Xrays that results in images that can be colored and more detailed. https://www.marsbioimaging.com/mars/ See this link for example. I do wonder what would be the major differences or benefits from such technology given modern MRI also has very...

As a lot of people know, when things go hypersonic or even orbital velocities in the atmosphere, it’s going to get hot, scorching hot. The air emits black body radiation that are at the red spectrum (around 2000 to 3000 kelvins) sometimes goes yellow (5000-8000 kelvins maybe?) at re-entry...

There are been many threads at PF on the perception of color. I would like to share a good video on the subject, which contains many interesting visual effects. This is from the Technology Connections channel, which has many videos of interest to our community. I encourage you to browse around.

Hi, I am aware that the reason why objects have color is an old subject. However I come across two claims which sound like they are in contrast to each other. On one hand I read that the photons with specific frequency in incoming light are absorbed (i.e. have enough energy to move an electron...

Colors come about because the wavelength is reflected off the object while the rest is absorbed. So orange looks orange because the orange is reflected while rest absorbed. For laser goggles that is rated for say 532nm (green wavelength). It must absorb the 532nm and so the reflected color...

In this article, writer says that when atom is hit by photon it gets excited and expelled out of atom and this can be used to form images. My questions are: Why didn't the electrons get to a higher energy level, instead of getting knocked out? How do we find the color(frequency of wave) using...

I was reading about why blue eyes look blue. After all, the human body does not create any blue pigment. It turns out, it's the same reason the sky is blue: the Tyndall effect. When there is minimal pigmentation, the first frequencies of light to scatter are the blue frequency waves. When there...