Question

2 electric bulbs marked 100 watt 220 volt and 200 watt 200 volt have tungsten filament of same length. which of the 2 will have thicker filament?

Answer 1

Hello friend
The resistance of 200W is lower than that in the 100W
Power= voltage*current= voltage*resistance and voltage is same
We know ,
resistance= resistivity*length /area
length and resistivity are same
so area is larger for 200W therefore,the 200w has the thicker filament
hope it help you friend
thanks!

Answer 2

We know, P = VI

For 100 W, 220 V rating bulb,

P=V^2/R = R=220*220/100 = 484 Ω

For 220 W, 200 V rating bulb,

P=V^2/R = 200*200/200=200Ω

Now, resistance is inversely proportional to thickness. Since, 220 W bulb has low resistance, its filament’s thickness will be more.