The luminous efficacy of a tungsten lamp is about 12 lumens/watt. What is the efficacy of a fluorescent tube (in lumens/watt)? Group of answer choices 80 50 20 100
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Luminous efficacy is a measure of how well a light source produces visible light, expressed in lumens per watt (lm/W). Show more…
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Find the total savings in electrical load and the percentage increase in illumination if instead of using twelve 150 W tungsten-filament lamps, we use twelve 80 W fluorescent tubes. It may be assumed that: (i) there is a choke loss of 25 percent of the rated lamp wattage, (ii) the average luminous efficiency throughout the life of each lamp is 15 lm/W, and for each tube is 40 lm/W, and (iii) the coefficient of utilization remains the same in both cases.
Penny R.
(II) The luminous efficiency of a lightbulb is the ratio of luminous flux to electric power input. (a) What is the luminous efficiency of a $100-\mathrm{W}, 1700-\mathrm{lm}$ bulb? $(b)$ How many $40-\mathrm{W}, 60-\mathrm{Im} / \mathrm{W}$ fluorescent lamps would be needed to provide an illuminance of $250 \mathrm{Im} / \mathrm{m}^{2}$ on a factory floor of area $25 \mathrm{~m} \times 30 \mathrm{~m} ?$ Assume the lights are $10 \mathrm{~m}$ above the floor and that half their flux reaches the floor.
Supreeta N.
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