Why do you see colors?

Answer 1

Because various substances called pigments absorb certain wavelengths of light and reflect others. What is reflected back to the eye appears as the color of the object.

Grass looks green, for example, because the pigments in it absorb all the wavelengths of sunlight except green, which is reflected back to us. When all wavelengths of light are absorbed, an object looks black. This would happen, for instance, if you were to shine only yellow or red light on a blue towel. Since the towers pigment reflects only blue and there is no blue in yellow or red light, the towel would absorb all the yellow or red light and appear black. Rather than a color, therefore, black is the absence of color.

Scientists speak of certain "primary colors." These are ones from which the greatest possible number of combinations can be made. The primary colors in light are red, blue and green. When red and blue light are combined, the result is a bluish-red called magenta. Mixing blue and green light produces a bluish-green called cyan. Red and green light go together to make yellow. All three combined give white light. Because wavelenths of light is absorbed by the 'colored' obect; this allows you to see color.

Answer 2

When light strikes a surface ,it changes it's frequency and when the light is reflected from that surface to human eyes ,the rod cells and cone cells inside which rodopsin and eyedopsin is present ,get certan signal from that light according to which our brain interprets different colors.