[labcomputer]

So lightbulbs actually dont have fixed resistance. The tempco is pretty big, and temperature of course depends on power (with an annoyingly large time lag when power is reduced).

That being said, the bulb does have a well-defined resistance at a given point in time, so voltage and current are of course not quantities that can be indefinitely controlled.

This falls into the same category as “why isn’t my power supply with voltage and current controls working correctly?!?”