Answer: I would say it would be 3.9
but i believe there is something missing shorty.
The colour we see is a measure of the wavelengths of light nor absorbed by the cloth. We would call the colour of the cloth blue if it absorbed longer wavelengths of yellow/orange/red. Sunlight contains all the visible wavelengths. Whatever is not absorbed is reflected.
Our eyes are detectors which are designed to detect visible light waves (or visible radiation). ... The electromagnetic spectrum includes gamma rays, X-rays, ultraviolet, visible, infrared, microwaves, and radio waves. The only difference between these different types of radiation is their wavelength or frequency.
