Radiation: the Filament in a Light Bulb Has a Diameter

question 43

Multiple Choice

Radiation: The filament in a light bulb has a diameter of 0.050 mm and an emissivity of 1.0. The temperature of the filament is 3000°C. What should be the length of the filament so it will radiate 60 W of power? The Stefan-Boltzmann constant is 5.670 × 10^-8 W/m² · K⁴.

• A) 11 cm
• B) 9.4 cm
• C) 8.6 cm
• D) 7.2 cm
• E) 5.9 cm

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