46011light

46011light - Light as an Ecological Factor 1. Underlying...

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Light as an Ecological Factor 1. Underlying principles a. Electromagnetic radiation as a form of energy b. Energy emitted by objects such as the sun, earth, organisms, spans a spectrum of wavelengths i. Amount of energy emitted is proportional to the fourth power of an object’s absolute temperature (Kelvin scale; Stefan-Boltzmann law) ii. The wavelength where maximum emission occurs is inversely proportional to the object’s temperature (Wien’s displacement law) c. Electromagnetic radiation has both wave and quantum (photon) properties d. The shorter the wavelength of radiation, the greater the amount of energy per photon e. Portions of the electromagnetic spectrum i. Visible light / Photosynthetically active radiation (PAR): approx. 400-700 nanometers (nm) ii. Infrared radiation - Near infrared: approx. 700-5,000 nm - Far infrared: approx. 5,000 nm - 100,000 nm iii. Ultraviolet radiation - UV-A radiation: 320-400 nm - UV-B radiation: 280-320 nm - UV-C radiation: 200-280 nm f. Possible interactions of light and matter:
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This note was uploaded on 10/27/2011 for the course BOT 460 taught by Professor Clambey during the Fall '11 term at ND State.

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