Understanding colors (Lights And Optics)

[zzoo4]

Well, This isn't a homework , but today in class we talked about how lights shining on a object produce different color. But I do not know what color it produces??

I know that Primary colors of light are red green and blue. Secondary are magenta and cyan and yellow.

If we have a red cherry on the desk and we shine yellow light, Why does it produce or reflect red?? Teacher said it reflects green but how?

And vice versa if we shine a red light into a yellow banana, we get red
and if we shine blue, we get black.. why??

Can someone help me understand why these colors are produced and how i can tell??

 

[jedishrfu]

light itself isn't organized as primary and secondary colors that is a result of your eyes ability to see color. You have three types of receptors:

http://en.wikipedia.org/wiki/Young–Helmholtz_theory

light itself is characterized by its frequency red light has a lower frequency than green or blue light.

the banana is yellow because it reflects that frequency and absorbs the other visible ones. as bananas age they go from green to yellow to brown (reddish) so its seems it would have a varying ability to reflect these colors but not blue and that's why you see black.

 

[zzoo4]

But what if you don't know the frequency. But just the color...

 

[nDever]

White light is composed of all of the frequencies in the visible portion of the electromagnetic spectrum. This means that all of the colors have a unique and corresponding frequency. Darkness is just the absence of light.

Whenever you "see" a color, this is the result of light frequencies being added together starting with darkness. This is called additive color.

Mixing light is not the same process as mixing pigments such as paint, crayons, or other dyes. Those "colors" are produced in a process called subtractive color in which the frequencies of light are subtracted from each other starting with white light.

The components in our body responsible for the perception of color vision are the cone cells located in the retina of our eyes and different cells respond to different frequencies of light.

So as jedishrfu has stated, when you perceive a that an object has color, it's because that the object absorbs all of the frequencies except for the ones that your photoreceptors respond to. Each color has a corresponding frequency; Theoretically, there are an infinite amount frequencies, therefore just as many colors. This is why the collection of colors is called a visible spectrum; It is a continuous band of frequencies. You can't separate a color from its frequency; The color is represented by it.

 

[asteriatic]

I can explain the phenomenon of colors in terms of the physics of light and optics. The colors we see are a result of how light interacts with objects and how our eyes perceive that interaction.

First, it is important to understand that light is made up of different wavelengths, each corresponding to a different color. The primary colors of light, as you mentioned, are red, green, and blue. These colors are called additive primary colors because they can be combined to produce other colors. For example, if we combine red and green light, we get yellow light.

Now, when light shines on an object, the object absorbs some wavelengths of light and reflects others. The wavelengths that are reflected determine the color of the object that we see. In your example of a red cherry under yellow light, the cherry appears red because it absorbs all the wavelengths of light except for red, which is then reflected back to our eyes. This is why the cherry appears red under any light source, because it always reflects red light.

Similarly, a yellow banana appears yellow because it reflects yellow light and absorbs all other wavelengths. When we shine a red light on the banana, it appears red because the red light is the only light that is being reflected back to our eyes. When we shine blue light on the banana, it appears black because the blue light is being absorbed and no light is being reflected back to our eyes.

In summary, the colors we see are a result of the interactions between light and objects. The colors that are produced depend on the wavelengths of light that are reflected by the object. I hope this helps you better understand the concept of colors in lights and optics.