Question

If we put a green leaf under a red light what colour will it appear?

Answer 1

It would appear black, just as any other green object would. The color green appears green because it reflects green wavelengths. Red wavelengths are much longer than green, and when only red light hits a green object, the red is absorbed and very little of the light is reflected back, so therefore the color appears black. When light hits a leaf the chlorophyll absorbs and uses the red and blue wavelengths and reflects back the green light to your eye, since it doesn’t use much of it.

absorbs all wavelengths of visible light spectrum except the green colour, and therefore it appears green as they reflect it. But when solely red light is given to the leaf, it will absorb the red light and therefore appears as black. As we know when all the wavelengths of the spectrum are absorbed, the subjected object appears black; and if they appear white, that means the object reflects the incident light.