Visible Spectrum to Human Eye
Human eye is sensitive to an approximate range of wave length of EM radiation from 380nm to 760nm. This portion of electromagnetic spectrum is identified as “visible light” These wavelengths roughly correspond to the colors violet, indigo, blue, green, yellow, orange, and red.
The visible spectrum (visible light) has infrared (IR) light below it (lower frequency) that we cannot see. It also has ultraviolet (UV) light (higher frequency) above it that we cannot see. There is a whole range of the electromagnetic (EM) spectrum that we cannot see below IR, and that includes all the radio waves. Above the UV is x-ray and cosmic ray radiation, and we can’t see that, either.