Asked by Gina

Does the filament of a bulb have constant resistance, constant voltage or constant current?

I would think it's constant current. But can someone logically explain why? I can't understand it much.
Answered by bobpursley
resistance changes with temperature, and temperature changes dramatically as the bulb heats up.

Current changes dramatically from turn on to heated condition.

Voltage remains constant from the supply, usually.
Answered by Gina
What about for an LED? Wouldn't that at least have constant current? I'm asking this because for an assignment where we had the previously stated question I put constant current which was marked correct. But with your help and research I've realized it should actually be constant voltage. So maybe I misinterpreted the question, if it was meant for LED filament then would it have constant current?
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