difficult to eliminate because it is equal to the Exitance of a Lambertian

Difficult to eliminate because it is equal to the

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difficult to eliminate because it is equal to the Exitance of a Lambertian surface. Luminance Unit relationships L = M / These relationships hold only for a Lambertian Surface. 1 cd/ft 2 = lms/ft 2 1 cd/m 2 = lms/m 2
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14 Inverse Square Law E = I / D 2 = cd / ft 2 = lm / ft 2 = lm/sr/ft 2 Note – This is how luminous intensity is measured. Inverse Square Cosine Law E = I cos i /D 2 i Accounts for the effective surface area which catches the lumens arriving from a particular direction (projected area). sr is unitless cd=lm/sr
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15 8 ft. I = 2000 cd E = I cos i /D 2 E = 2000 cd / 8 2 E = 31.3 fc = 336 lux 8 ft. I = 2000 cd E = I cos i /D 2 E = 2000 cos(20) / 8 2 E = 31.3 cos(20) = 29.4 fc n 20°
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