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Light

Light is energy that propogates from a source and interacts with the physical world through reflection, transmission through refraction, absorption and detection.

Light is a form of electromagnetic energy traveling in straight lines in all directions from its source. This rectilinear propogation is in the form of a sinusoidal wave having both an amplitude and a frequency.

In physics term, a wavelength of light energy is noted by the greek symbol "lambda" or λ and can be defined by the following equation:

λ = c / v

where:
λ: wavelength
c: speed of light in a vacuum 3.00 x 10⁸ meters per second
v: frequency

Light is one of many manifestations found in the electromagnetic spectrum. The others, from longest to shortest; radio, micro, infra-red, visible, ultraviolet, x-ray, gamma. Visible light, with wavelengths ranging from 380nm to 760nm, can be detected by the human eye. Visible light consists of a band of colors, each with its corresponding wavelength. The following chart (courtesy of wikipedia) identifies this spectrum and the visible region.

As light energy travels through space and encounters matter it will do one of the following; reflect as in a mirror, transmit or refract as in a prism, absorb as in heated products, detect as in a photo camera sensor.

When light travels through a medium having an opaque feature, the speed and angle at which the rays travel through the medium will vary based on the medium's refractive index. This is evident in the prism showing visible white light entering one side and each constituent color wavelength exiting the other side at varying degrees resembling the colors of a rainbow.

Designers and engineers use various materials, shapes and coatings to bend, reflect, and relay light rays to their advantage. This includes, grinding and polishing glass to refocus wavelengths and or recoating these surfaces with exotic materials to filter unwanted rays that may adversely affect the final image quality.

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