Practice problems using the Stefan-Boltzman Equation and Wein’s Law:
SB constant: 5.67 x 10-8Wm-2K-4
Wein’s Law constant: 2897
1. How much energy is emitted by a surface whose temperature is 230 K?
158.67 Wm-2
2. If an object has a temperature of -180 degrees C, how much energy per square
meter does it emit?
4.24 Wm-2
3. What is the temperature of a surface that emits 0.0000000043 W per square
meter?
0.525 K
4. If Oven A has a λmax of 6 μ and Oven B has a λmax of 7 μ , which oven is cooler?
Show work.
Oven A : 483 K
Oven B : 414 K
5. 5.0 x 10 -9 W per square meter strikes a field of grass with an average albedo of
0.6. How much energy is reflected? How much is absorbed?
3 x 10-9 reflected; 2 x 10-9 absorbed
Additional Practice:
Using a radiation sensor, you detect 401 Wm-2 radiating from a surface. Solve for
temperature.
(Answer: 290 K)
If a furnace emits radiation with a wavelength of peak intensity at 100
micrometers, what is its temperature?
(Answer : 28.97 K)
If the surface temperature of the earth is 27°C, what is its wavelength of peak
intensity?
(Answer: 9.66 µ)
If an object has a temperature of 32°F, how much radiation does it emit?
(Answer: 314.9 Wm-2)