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I have a task to compare between fluorescent light sources and LEDs, i want to know what are the parameters that i have to keep constant while measuring light intensity and how can i compare them with each other? what do i have to do so that its a fair comparison?
Good question. The overriding economic consideration in comparing light sources is illumination (Lumens) versus electrical power (Watts). See: http://en.wikipedia.org/wiki/Lumen_(unit)
What you have to do is to measure the light intensity with a photo cell or light meter and at the same time the amount of power needed to drive the bulb. The power is proportional to the voltage, usually 110 AC for florescent bulbs, times the current supplied to the bulb. You can measure the current with an AC ammeter. Be careful in connecting the ammeter, make sure the plug is disconnected. LEDs are usually driven with a much lower DC voltage. You still have to multiply Volts times Amps but in this case it's direct current.
(published on 03/25/09)
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