PRINCIPLES AND UNITS


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PRINCIPLES AND UNITS
PRINCIPLES AND UNITS1. Explanation of light. For the principal purposes of illumination design, light (Standard Handbook for Electrical Engineers) is defined as visually evaluated radiant energy. The visible energy radiated by light source is found in a narrow band in the electromagnetic spectrum, approximately from 380 to 770 nanometers (nm). Figure 10.1 shows the complete radiant-energy spectrum of electromagnetic waves, which travel through space at the velocity of approximately 3.0 × 108 m/s (186,000 mi/s). The longer waves are the ones used in radio communications; the shortest ones are the x-rays and cosmic rays. An enlarged sec…
Citation
Terrell Croft; Frederic P. Hartwell; Wilford I. Summers: American Electricians' Handbook, Sixteenth Edition. PRINCIPLES AND UNITS, Chapter (McGraw-Hill Professional, 2013), AccessEngineering Export