UPSC 2013 CDS 2 GK Paper

Among the given colours, Red colour (620 - 780 nm) has thehighest wavelength. The order of colours in light, arranged fromshortest wavelength to longest, is called the visible spectrum of light.Wavelength increases on moving to bottom from top:
Violet: 400 - 420 nm.
Indigo: 420 - 440 nm.
Blue: 440 - 490 nm.
Green: 490 - 570 nm.
Yellow: 570 - 585 nm.
Orange: 585 - 620 nm