LED bulb question

[FrankJ]

Originally Posted by Ether

The resistance of the bulb changes substantially as the filament gets white hot.

I don't have a DVM that uses 120 volts to measure resistance.

.

There is always the amp function of your DVM.

The cold resistance gives you a reference to tell if things are really strange. You can also make some assumptions and do a little math and see if a simple physics model matches reality. Tungsten (assuming your filament is really tungsten) has a resistance temperature Cef of 4.5E-3 at 20C. (Assuming it is linear all the way to white hot is a big assumption at least for me.) Using 120 VAC for the rated voltage 2500K as the bulb temp and a little excel math I get about 22 ohm cold. Am I close? Of course with a 240ish ohm hot resistance the cold resistance doesn't tell you that much without a tested model.