A typical 60-watt standard frosted incandescent bulb outputs 890 lumens for an efficacy ratio of about 15 lumens per watt. As an A19, its shape is spherical. What is the its calculated luminance? A. 25,115 cd/in² B. 25.115 cd/ft² C. 25,115 cd/m² D. Indeterminate, missing variable. Answer If 1 candela (cd) = 4 ∏ lumens (lm), 890 x 1cd/4∏ = 71 cd, A19 = 19/8 = 2.375 in or 60mm diameter (= 30mm radius), L = intensity / projected area, 71 cd / ∏ r² = 71/ 3.14 x (.03m)² = 25,115 cd/m² ARE 4.0 exam prep: BS
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Maybe check that you have an updated browser. I know some older IE versions like IE 6 don't properly display the feature (FYI - it's a 'tooltip' made with CSS3 stylesheet language). Otherwise Firefox, Safari, Chrome should work.
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