In a circuit that is fitted with a bulb, which is the factor that affects brightness of that bulb: current in the circuit or the voltage offered by the battery in that circuit?
[Physics] Among current and voltage which is responsible for brightness of a bulb
electric-currentelectrical-resistanceelectricityvoltage
Best Answer
Both. It's the power that ultimately causes the filament to get hot and emit visible black body radiation.
Power is voltage times current, so both matter.
However, you can only control one degree of freedom. The bulb dictates the other. This single degree of freedom can be expressed various ways. Two of them are fixing the current and fixing the voltage. Once you fix one of these, the resistance of the bulb implicitly fixes the other.
Note that the resistance of a bulb varies considerably with temperature. It is much higher when the bulb is emitting light than when it is sitting cold and unpowered. However, that still doesn't let you fix both independently. It only means that the relationship between voltage and current changes with the set point.