Question

The electric bulbs have tungsten filaments of same length. If one of them gives 60 watt and other 100 watt, then

• A. 100 watt bulb has thicker filament
• B. 60 watt bulb has thicker filament
• C. Both filaments are of same thickness
• D. It is possible to get different wattage unless the lengths are different

Answer 1

Answer: (A)

100 watt bulb has thicker filament

Answer 2

$P_{Rated} \propto \frac{1}{R}$and $R \propto \frac{1}{(\text{Thickness offilament})^{2}}$

So $P_{Rated} \propto (\text{Thicknessoffilament})^{2}$