RE: Breaking the myth: Incandescent bulbs don't last
January 15, 2016 at 7:17 am
(This post was last modified: January 15, 2016 at 7:25 am by Alex K.)
Just some things that come to mind concerning your calculation -
It is conceivable that the 200W bulb will draw a bit more than 60W (i.e. (120/220)^2 times the power) at reduced voltage because the resistance will be noticeably lower at the new operating point as compared to 200W. Also, it is possible that the 200W bulb running with 60W will have lower filament temperature than a regular 60W bulb, thus reducing the efficiency in visible light, so there might be a trade off between longevity and efficiency. Those are just ideas, I don't know how big these effects are.
p.s. standard voltage has been 230V for some time now, at least in Germany
It is conceivable that the 200W bulb will draw a bit more than 60W (i.e. (120/220)^2 times the power) at reduced voltage because the resistance will be noticeably lower at the new operating point as compared to 200W. Also, it is possible that the 200W bulb running with 60W will have lower filament temperature than a regular 60W bulb, thus reducing the efficiency in visible light, so there might be a trade off between longevity and efficiency. Those are just ideas, I don't know how big these effects are.
p.s. standard voltage has been 230V for some time now, at least in Germany
The fool hath said in his heart, There is a God. They are corrupt, they have done abominable works, there is none that doeth good.
Psalm 14, KJV revised edition
