Sequence of colors in a rainbow
Physics   Wikipedia  
Sequence of colors in a rainbow or visible spectrum: red, orange, yellow, green, blue, indigo, violet

 Mnemonic:
"Richard Of York Gave Battle In Vain"

 Mnemonic:
"Riding On Your Granny's Bike Is Vile"

 Mnemonic:
Roy G. Biv is also used as a fictitious name