A simple definition of the Visible Spectrum
To get an idea of the size of visible light’s wavelengths we need a new term: the “nanometer”. A nanometer is a millionth of a millimeter or a billionth of a meter (There are 25,400,000 nanometers in a single inch). The human eye see visible light when the energy has wavelengths between approximately 400 and 700 nanometers. That’s wavelengths between 400 and 700 billionths of a meter. The wavelengths of visible light are very, very small.
Colors visible to the human eye are found at the following approximate wavelengths:
• Violets and Blues between 400 nm and 480 nm
• Greens between 480 nm and 560 nm
• Yellows between 560 nm and 590 nm
• Oranges between 590 nm and 630 nm
• Red between 630 nm and 700 nm
A commonly taught acronym that helps people remember the colors in the visible spectrum is ROY G BIV which stands for Red, Orange, Yellow, Green, Blue, Indigo, and Violet. Indigo and violet are included in the blue region of the visible spectrum, but can be seen separately. These were the seven colors originally identified by Sir Isaac Newton in his prism experiment.