Thursday, May 7, 2009

Colours - pigment and light?

A painting of a person wearing a yellow shirt is observed under white light. The yellow pigment in the painting:


A) Absorbs yellow, orange and green light


B) Reflects red, blue and violet light


C) Absorbs red, blue and violet light


D) ABsorbs only yellow light





I'm sure it's C but not sure why...

Colours - pigment and light?
None of the above. The yellow pigment absorbs blue light and reflects red and green.
Reply:Yeah, your textbook is a little stange because its talking about the full spectrum from red to violet in the normal: red, orange, yellow, green, blue, violet. It gets confusing talking about all the colors of the spectrum, because a spectrum is really a continuous gradation of light from the red end to the violet end, not discrete colors at all. Scientists typically break the visible spectrum into 3 primary colors, red, green and blue, because you can characterise any color as a mixture of these three. That's what the other guy is saying.





But your answer is correct, given the choices. C.





The pigment reflects more yellow than any other color, and maybe its reflecting orange and green but you don't really know. It might be reflecting lots of red and violet as well. The key is that its reflecting things that add up to predominantly yellow.


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