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The Science of Rainbows - Introduction

These pages are my notes on how rainbows and related phenomenon occur. Note that this is a passion project made by an amateur, I may make mistakes.

The Visible Spectrum

The visible spectrum is a portion of the electromagnetic spectrum; the electromagnetic spectrum organizes photons by their wavelengths. A photon is a particle of energy that can only be whole (discreet). Photons move at the speed of light, with light being a form of energy and heat being another. Photons travel in waves, and the wavelength of these waves determines their properties (hence the separation of the electromagnetic spectrum into categories).

The shorter the wavelength, the higher the frequency, thus the higher the energy

The photons (energy) in the visible spectrum take the form of light. Infrared radiation (radiation is the emission of energy) is heat. Visible light, infrared radiation, microwaves, and radio waves are forms of nonharmful radiation, as the photons do not have enough energy to break chemical bonds or ionize molecules. UV radiation, X-rays, and Gamma rays are harful to living cells because the photons do have enough energy to cause chemical reactions.

Each wavelength (380-750 nm) corresponds to a different color. Violet wavelengths are the shortest and red are the longest.

Where is purple?

Notice how the visible spectrum (defined by individual wavelengths) spans from blue to red, but light can come in more colors (magenta, purple, white, etc).

This is because colors like magenta, purple, and white are made by different wavelengths of light mixed together. White light is an even mixture of all wavelengths, magenta is an equal mixture of blue and red, and purple is also a blend of blue and red but with a higher ratio of blue. In short, these colors do not have their own wavelengths.

Suggested Next Pages:

Prisms and the Rainbow
RGB - the Primary Colors of Light?