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ILLUMINATION IN ELECTRICAL ENGINEERING


What is Lighting a.k.a Illumination? 
Lighting or illumination is the deliberate application of light to achieve some practical or aesthetic effect. Lighting includes the use of both artificial light sources such as lamps and light fixtures, as well as natural illumination by capturing daylight. Daylighting (using windows, skylights, or light shelves) is often used as the main source of light during daytime in buildings. This can save energy compared with artificial lighting, which represents a major component of energy consumption in buildings. Without proper design, energy can be wasted by using too much light, or using out-dated technology. Proper lighting can enhance task performance, improve the appearance of an area, and have positive psychological effects on occupants. One of the core tenets of proper lighting is uniform illumination, which is required in many applications such as projection displays, LCD backlights, medical lighting, microscopy, solid-state lighting, and general lighting.continue..


In the beginning of science there was Aristotle. In terms of looking at the world from a “scientific” perspective, there was no one better in the Greek world (nor would there be until the Renaissance). For centuries, what Aristotle said was held as scientific scripture – unquestionable, lest one be accused of scientific heresy (just ask Galileo, who was forced to recant his own anti-Aristotelian views). While he was well-published in many areas, his views on the phenomenon of light was graciously simple: Light, he said, is nothing of substance. It is indefinable, featureless, and it is therefore pointless to contemplate its nature.continue..

Many of the early scientists who studied sound also studied light. Pythagoras, for example, believed that light came from visible objects toward the eye. However, in addition to this basically correct thought, Plato and many other Greeks, also held the mistaken belief that vision issued out from the eye. Despite this, many of the ideas of the ancient Greeks were accurate. The philosopher Empedocles correctly believed that light traveled with finite speed. Aristotle, too, conjectured about light as well as sound. He rightly explained rainbows as a sort of reflection off of raindrops. The mathematician Euclid worked with mirrors and reflection, and many other thinkers observed refraction, though they did not know how to express it mathematically. continue..

To the optical engineer, light is simply a very small part of the electromagnetic spectrum, sandwiched between ultraviolet and infrared radiation. The visible portion of the electromagnetic spectrum extends from about 380 to about 780 nanometers (nm), as shown in Figure 1.1. What distinguishes this part of the electromagnetic spectrum from the rest is that radiation in this region is absorbed by the photoreceptors of the human visual system and thereby initiates the process of seeing. The Illuminating Engineering Society of North America (IESNA) defines light as “radiant energy that is capable of exciting the retina and producing a visual sensation.” Light, therefore, cannot be separately described in terms of radiant energy or of visual sensation but is a combination of the two continue..

The problem of the lighting designer at the functional level is to determine how many lights and where to place them to get the correct level of illumination for a given activity.  We want to determine the illumination at a small specific location in the room from a point light source.  Accent or task lighting. This not much more complicated than exercises we have already been doing continue..

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