https://twetch.app/t/b955ac29a2b93ecde245d893e7ccc02266978b…

https://twetch.app/t/b955ac29a2b93ecde245d893e7ccc02266978b90d46c1a6e75661b3c25dc3a3b
4×10^14 Hz is red light
8×10^14 Hz is violet light
and between these (in the range 4-8×10^14 Hz) are all the other colors of the visible spectrum.