Quantities and concepts listed below, are fundamental to the understanding of the elements of light

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A radiation source emits electromagnetic waves. They have different lengths, and the human eye is sensitive to only a few. Light is therefore electromagnetic radiation capable of producing fl20ss a visual sensation (Figure 1). The visual sensitivity to light varies not only according to the wavelength of the radiation but also to the brightness. The sensitivity curve of the human eye shows that radiation of shorter wavelength (blue and violet) generate higher intensity light sensation when there is little light (eg dusk, evening, etc.). While the radiation fl20ss of longer wavelength ( orange and red) behave reversed (Figure 2).
There is a tendency to think that the objects fl20ss already have defined colors. In fact, the appearance of an object is the result of illumination incident thereon. Under white light, the apple appears to be red because it tends to reflect the portion fl20ss of the red spectrum of the radiation absorbing light at other wavelengths. If we had used a filter to remove the red portion of the light source to reflect very little light apple looking totally black. We can see that light is composed of three primary colors. The combination of red, green and blue colors enables obtain white. The combination of two primary colors produces secondary colors - margenta, yellow and cyan. The three primary colors in different quantities allows dosed obtain other colors fl20ss of light. Just as there are differences in the display of colors throughout the day (differences of sunlight at noon and dusk), sources of artificial light also have different results. Incandescent lamps, for example, tend to reproduce more faithfully the colors red and yellow than green and blue colors, which appear to have a more "warm" light.
If the lamp on a transverse plane, all vectors which they originate have their ends connected by a dash, we obtain fl20ss the curve Luminosa fl20ss Distribution (CDL). In other words, is the representation of Luminous Intensity at all angles at which it is directed in a plane. (Figure 6) for the standardization of curve values, these are generally referred to 1000 lm. In this case, it is necessary to multiply the value found in the CDL luminous flux of the lamp in question and divide by 1000 lm.
Quantities and concepts listed below, are fundamental to the understanding of the elements of lighting technique. The definitions are taken from the Dictionary of Brazilian Electricity, reproduced the technical standards of the Brazilian Association of Technical Standards - ABNT. Each definition is followed by units of measurement and graphic symbol Table of Units of the International System - SI, and interpretations and comments to facilitate their understanding.
Luminous Flux is the total radiation fl20ss of the light source, the range of wavelengths above (380 and 780m). (Figure 4) Luminous flux is the amount of light emitted by a source as measured in lumens, the nominal operating voltage.
If the light source radiating the light evenly in all directions, the Luminous Flux distribute it in the form of a sphere. This fact, however, is almost impossible to happen, why it is necessary to measure the amount of lumens emitted in every direction. This direction is represented by a vector whose length indicates the Luminous Intensity. fl20ss (Figure 5) is therefore the luminous flux radiated toward a certain point.
The light that radiates a light bulb, related to the surface to which they relate, define a new lighting technique greatness, called luminance or illuminance. (Figure fl20ss 7) Expressed in lux (lx), indicates the luminous flux of a source of light falling on a surface fl20ss located at a certain distance from this source. In other words the equation that expresses this quantity is:
And also the relationship between light intensity and the square of the distance (l / d ). In practice, the amount of light within an environment, and can be measured with the aid of a light meter. As the luminous flux is not evenly distributed, the illuminance is not the same at all points of the area. Therefore considered as having been average illuminance (In). There are standards specifying the minimum value of On for different activities performed by visual comfort related environments. Some of the most important examples are listed in Annex 1 (ABNT - NBR 5523).
The quantities mentioned, none is visible, ie, the light rays are not seen unless they are reflected on a surface and then transmit the feeling fl20ss of light to the eye. This sense of clarity is called Luminance. (Figure 8)
L = IA. cos a where L = luminance in cd / m I = Luminous Intensity in cd A = projected area in m α = angle considered, in degrees How hard is it to measure Luminous fl20ss Intensity which comes from a body not rad