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The history of light: the spectrum

Let’s start with Isaac Newton. It is the year 1666. In a room with closed shutters, he works with a small opening to isolate a single ray of sunlight. In the stream of light, he places a glass prism: Via refraction, the light breaks down into a rainbow of colors: Red, orange, yellow, green, blue, indigo, violet. In reality, indigo does not exist in the spectrum, but Newton added it for good measure (at that time, the number 7 was thought to be endowed with magical and mysterious properties). Seven colors. Light would remain divided into seven colors for the entire 18th century, called the “century of light”, since philosophers were convinced they were entering a new age illuminated by Reason…

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 The Color of Light

Light is a kind of energy called electromagnetic radiation. There are many different forms of electromagnetic radiation, such as radio waves, microwaves, ultraviolet rays, and X-rays. Each form is characterized by a different wavelength. For example, radio waves can be several miles long, while gamma rays are smaller than atoms. The light that we see — visible light — falls somewhere in the middle of this "electromagnetic spectrum."

Articles of Interest

What is light? The visible spectrum and beyond

Today we recognize that light possesses both a wave and particle nature. It is also clear that the limits of visibility really extend from about 310 nm in the ultraviolet (in youth) to about 1100 nm in the near-infrared, but depend very much on the radiance, that is, ‘brightness’ of the light source. The spectral content of artificial lighting are undergoing very significant changes in our lifetime, and the full biological implications of the spectral content of newer lighting technologies remain to be fully explored.

The spectrum of visible light, the wavelength of the light

The wavelength of visible light determines, among other things, how we perceive the color of a given radiation. All colors of visible light have specific wavelength ranges for themselves. The shorter the wavelength, the more the light is concentrated in colder colors, such as blue, while longer wavelengths are responsible for warm colors, such as red and orange. Knowledge of the wavelength of visible light is of great importance in many areas of our everyday lives - from science, through medicine, to technology.

Tour of the Electromagnetic Spectrum: Visible Light

See just how narrow the visible light band is relative to other EM energy – and why, despite that, it’s crucially important to humans. Explore the relationship between color and temperature, the appearance of the atmosphere (and why the sky is blue!), and how scientists use light scattering to figure out what things are made of - both on and off Earth - in this video from NASA.

What Is the Visible Light Spectrum?

The visible light spectrum is the section of the electromagnetic radiation spectrum that is visible to the human eye. Essentially, that equates to the colors the human eye can see. It ranges in wavelength from approximately 400 nanometers (4 x 10 -7 m, which is violet) to 700 nm (7 x 10-7 m, which is red).1 It is also known as the optical spectrum of light or the spectrum of white light.