Small lighting knowledge | what is the luminous intensity of light source? - China lighting network

In the darkness of the environment, we used to use a flashlight to light, small flashlight on the direction of the lighting shoot can emit strong light, some even more than the volume is much bigger than it of light source, this is because the flashlight in the luminous intensity is greater than be compared in the direction of the light source, despite its luminous flux is not big. The luminous intensity or intensity, it is used to represent the light source in a direction luminous intensity degree of optical measurement. The light intensity of a light source in a given direction, Symbol for I) Equal in containing the luminous flux divided by solid Angle from the direction within the solid Angle of yuan yuan shang Φ I = d/d Ω. A quantity of solid Angle is the representation space scope. The luminous intensity of the international system of units ( SI) The unit is candela ( cd) , is one of the seven basic unit SI. In 1979 international conference on measurement by the new definition of candela candela is the luminous intensity of a light source in a given direction, 540 x 1012 hz frequency as the source, Hz) Of monochromatic radiation and the radiation intensity in the direction of ( 1/683) W/sr( Reading of watts per steradian) 。 The luminous intensity of a normal candle approximately 1 CD. YanZhiXiang

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