Question

The resistance of a 100W light bulb, as measured with the DMM, is 9Ω. Household power is 110V. Using a power equation, how much power would you expect the light bulb to use? What’s going on here? Is the light bulb a linear circuit component? If not, what accounts for its nonlinearity? Which power number is right? Why is the other power number wrong?

I used P= V²/R = (110)²/9 = 1,344.44W, but I don't know if I am correct in saying that because as temperature increases, so does the resistance, so in order to drive more current to compensate, you need to apply more voltage. I don't know if that's right, because it would still be linear, and I'm assuming by the way the question was asked, it is not linear. But why?

Answer 1

Initially when we start provide the power to the bulb its filament start glowing with the time and its temperature also increases.

Since at the initial time when we switch on the bulb then it showing resistance 9 ohm and at that time power required

But after some time as we know filament temperature increase then resistance of filament also will be increased because as we know that resistance of any material directly proportional to its temperature. Hence when bulb temperature increased than its resistance also increases.

So from power equation for fixed voltage (V= 110 volt ) power required of bulb depends on its resistance. Hence when increase the resistance then its power will be decreases. Finally when bulb glow properly than power require to the bulb only 100 W.

Hence we can conclude that initially bulb behave like nonlinear because its resistance increases with the time and power decreases but when it properly glow then its resistance and power required become fixed now it behaving like linear conduction.

So only 100 W power is rights remaining no of power in not correct.