UPSC CDS 2 2018 GK Paper

The visible portion of the electromagnetic spectrum is light. Visible rays are the most familiar form of electromagnetic waves.
It is the part of the spectrum that is detected by human eyes. It runs from about 4×1014Hz to 7×1014Hz or a wavelength of about 700−400nm.
Infrared, radio waves, microwaves, etc., are not visible portion of electromagnetic spectrum.