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What is the running temperature of a 100w bulb if it's resistance while on is 50 ohms and the mains voltage is 240 V RMS.

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  • $\begingroup$ Do you mean the temperature of the incandescent filament, or the temperature of the outer surface of the bulb? $\endgroup$ – probably_someone Mar 5 '18 at 14:35
  • $\begingroup$ The incandescent filament $\endgroup$ – Rick Saget Mar 5 '18 at 14:37
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    $\begingroup$ I'm voting to close this question as off-topic because of insufficient research effort. An answer is easily found in the featured hit found by googling the question title : pacificlamp.com/temperature-of-a-100-watt-bulb.asp $\endgroup$ – sammy gerbil Mar 5 '18 at 14:41
  • $\begingroup$ This is a duplicate, but also you can't compute the temperature from that information: you can compute the power output, but that is not enough to know the temperature. $\endgroup$ – tfb Mar 5 '18 at 14:51
  • $\begingroup$ It is about the same as that of a 6 volt 0.05 amps bicycle light. $\endgroup$ – Pieter Mar 5 '18 at 15:04
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This is an old black body experiment. Typically you would use the Stefan–Boltzmann law ( P proportional to T^4), but keep in mind the filament is not a perfect black body so a correction factor will be need to get your answer. Since you know the power from V^2/R.

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