試題詳解

60. A 100-W light bulb is made from a glass sphere with a radius of 3.0 cm and a thickness of 0.5 mm. It consumes 100 W of electricity and produces 95 W of heat, which is dissipated through the glass bulb. The thermal emissivity of uncoated smooth glass is about 0.9. The value of the Stefan-Boltzmann constant is σ = 5.67 10^-8 W/m².K⁴. The thermal conductivity of glass is 0.84 J/sㆍmㆍ℃. Which of the following values is closest to the temperature difference (K) between the inner and outer surfaces of the glass?
(A)20.0
(B)10.0
(C)5.0
(D)2.0
(E)0.4