Yes the hot vs. cold resistance will make the biggest difference. But even if you could measure the hot resistance, you would still be off by the 43/60 watt ratio.
GE example of a "60W replacement" being 43W: https://www.staples.com/GE-Energy-E...tt-Equivalent-Soft-White-66247/product_163215
Which are more efficient solely because of the higher filament temperature. All the halogen fill does is recycle the evaporated tungsten to allow for a higher filament temperature with good life.Because the 43watt bulbs that used to equal 60’s tungsten are actually halogen.
190130-2452 EST
Dennis:
From responses you provided I don't see that you really understand what is happening.
Get a Variac and do some tests. But even without the Variac measure the room temperature resistance of a 100 W tungsten bulb with a Fluke DVM.
Another simple test to do is a V, I measurement with a 100 W 120 V tungsten bulb connected to a 12 V car battery.
Relative to inrush current see my first two plots at http://beta-a2.com/EE-photos.html .
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It was all part of the energy savings act along with the phase out of incandescent lamps. As part of that act, to get people to save energy, bulbs labeled as 60 watt officially became something like 43 watt lamps.
You can see the schedule here
https://www.bulbs.com/learning/phaseoutschedule.aspx
Edit:
Yes the hot vs. cold resistance will make the biggest difference. But even if you could measure the hot resistance, you would still be off by the 43/60 watt ratio.
190201-0610 EST
100 W tungsten bulb at 12.4 V DC is 0.25 A or 49.6 ohms and a very dim glow.
Might be able to run a variable voltage test with a Lutron CL dimmer adjusted for maximum phase shift range and use of good RMS meters. I don't believe you can get as low as 12 V.
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OK, but I'm not sure what this experiment is intended to demonstrate?
You just had to throw that 43/60 in there. I was feeling good with the answers now tell me how you got 43/ 60
I agree, it would. But you can calculate the hot resistance from rated voltage and power. A regular DVM will give you the cold resistance. The RTC of tungsten gives you intermediate values between cold and operating temperature which is around 2500C.I believe he is trying to demonstrate the resistance curve of the tungsten lamp as it heats up. Measuring V & I across the range of the Variac would do this.
Since the general public doesn't know what a lumen is..., the energy efficient bulbs get compared to something that people actually can relate to,....
I agree, it would. But you can calculate the hot resistance from rated voltage and power. A regular DVM will give you the cold resistance. The RTC of tungsten gives you intermediate values between cold and operating temperature which is around 2500C.
You just had to throw that 43/60 in there. I was feeling good with the answers now tell me how you got 43/ 60