Light - Color

Question 1

light

Answer 1

• The wavelength of light waves can be anything, from extremely small to gigantically large. The light that our eyes can detect is called “visible light,” and it covers a small range of wavelengths, from 400 nm to 700 nm. (Recall, n = nano = 10-9, so a nanometer “nm” is a billionth of a meter.) Our brains perceive different wavelengths of visible light as different Colors. The colors break down approximately like this:
• This range of wavelengths and colors is called the “Visible Light Spectrum,” and contains “all the colors of the rainbow.” Other colors, like brown and pink, are mixtures of these basic colors. You can mix different wavelengths of light in different proportions to create any possible color.
• The more colors of light you mix together, the brighter the light gets. If you mix all colors of light equally, your brain perceives that as “white.” White light is therefore a mix of all colors at once. If there is no light at all, your brain perceives that as “black.” Black is the absence of light.
• When light hits an object, the molecules of the object may absorb the light or reflect it. If the object reflects all the light that hits it, the reflected light will have all colors, so the object will appear white. If the object absorbs all the colors that hit it, you will see no light coming off of it, so it will appear black. If the object absorbs some colors, but reflects the others, you see only the reflected light, and that’s what gives the object its color. For example, if a T-shirt reflects green light, and absorbs all the other colors that hit it, it will appear green.

Question 2

color

Answer 2

• 400 – 450 nm = Violet
• 450 – 500 nm = Blue
• 500 – 550 nm = Green
• 550 – 600 nm = Yellow
• 600 – 650 nm = Orange
• 650 – 700 nm = Red