How many nanometres does red have?
Red is the color at the end of the spectrum of visible light next to orange and opposite violet. Red color has a predominant light wavelength of roughly 620–740 nanometres. Red is one of the additive primary colors of visible light, along with green and blue, which in Red Green Blue (RGB) color systems are combined to create all the colors on a computer monitor or television screen. Red is also one of the subtractive primary colors, along with yellow and blue, of the RYB color space and traditional color wheel used by painters and artists.