02:27
University Physics with Modern Physics
Size of a Light-Bulb Filament. The operating temperature of a tungsten filament in an incandescent light bulb is 2450 $\mathrm{K}$ , and its emissivity is $0.350 .$ Find the surface area of the filament of a $150-\mathrm{W}$ bulb if all the electrical energy consumed by the bulb is radiated by the filament as electromagnetic waves. (Only a fraction of the radiation appears as visible light.)