Rate of energy flow in radiation (14-22)

Question 1 of 5

Question

Surface area of the object

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Question

Stefan-Boltzmann constant $= 5.6704 \times 10^{−8}\ \mathrm{W} \bullet \mathrm{m}^{−2} \bullet \mathrm{K}^{−4}$

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Review

The higher the temperature of an object of a given size, the greater the radiated power $P$ and so the more brightly it glows.

Experiment also shows that the color of the radiation emitted by an object depends on its temperature $T$ (Figure 26-4). A heated object emits light at all wavelengths, but emits most strongly at a particular frequency called the frequency of maximum emission. As the temperature increases, the frequency of maximum emission increases.

Equation 14-22 shows that the radiated power also depends on a quantity $e$ called the emissivity, which depends on the properties of the object’s surface. This has its greatest value $(e = 1)$ for an idealized type of dense object called a blackbody. An ideal blackbody does not reflect any light at all, but absorbs all radiation falling on it.