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| Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#41
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Slightly OT. Heat and a Bench Light ...
"Jeff Liebermann" wrote in message ... On Mon, 7 Jul 2008 09:53:39 +0100, "Arfa Daily" wrote: The things I do for science !! Cease complaining. It's your question that I'm trying to answer. Never mind that I don't know anything about light bulbs. I have two other types from the same stable, and one of the boxes has an energy rating on it, and one doesn't, so I'll have to look next time I am in the store. Methinks there will be a difference in efficiency rating. If true, that implies that the newer smaller bulb is really a Halogen filled bulb, even though it's not marked as such. OK. On the diameters. Consider them for all practical purposes, to be a sphere. The old was 60mm almost exactly, and the new, 50mm almost exactly, measured with an electronic calliper, so reasonably accurate figures. Surface area of a sphere is 4Pi*r^2 Old = 4 * 3.14 * 3.0^2 = 113.0 sq cm New = 4 * 3.14 * 2.5^2 = 78.5 sq cm The new bulb has about 70% of the surface area as the old bulb. However, I gotta dust off the college thermodyamics texts before I can figure out the expected temperature rise given identical power dissipations. I also gotta lookup the IR transmissivity of glass. The things I do for science... -- Jeff Liebermann I was in the store today, and had a look at the boxes these bulbs are in. There is no mention at all of them being a halogen type, but all of the ones that are genuinely halogens, do say so. The energy rating on the box was "E" Arfa |
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