Please provide a rating, it takes seconds and helps us to keep this resource free for all to use
Welcome to our Physics lesson on Stefan-Boltzmann Law, this is the fourth lesson of our suite of physics lessons covering the topic of Thermal Radiation. Photon as the Quantum of Light, you can find links to the other lessons within this tutorial and access additional physics learning resources below this lesson.
This law expresses the relationship between the total emissivity of a black body and its temperature. It says:
"Total emissivity of a black body is proportional to the fourth power of absolute temperature."
Mathematically, we write:
where σ = 5.67 × 10-8 J/K4m2s is a constant; it is known as the Stefan-Boltzmann constant.
Calculate the power of radiation emitted by the window of an oven which has an area of 200 cm2. The oven is at 15230 C and its window is considered as a black body.
Clues:
A = 200 cm2 = 0.02 m2 = 2 × 10-2 m2
T = 1523° C = (1523 + 273) K = 1800 K = 1.8 × 103 K
(σ = 5.67 × 10-8 J/(K4m2s)
P = ?
Since the unit of total emissivity E is [J/s·m2] or [W/m2], we obtain
Thus, the power of radiation emitted by the oven is
You have reached the end of Physics lesson 19.1.4 Stefan-Boltzmann Law. There are 6 lessons in this physics tutorial covering Thermal Radiation. Photon as the Quantum of Light, you can access all the lessons from this tutorial below.
Enjoy the "Stefan-Boltzmann Law" physics lesson? People who liked the "Thermal Radiation. Photon as the Quantum of Light lesson found the following resources useful:
Please provide a rating, it takes seconds and helps us to keep this resource free for all to use
We hope you found this Physics lesson "Thermal Radiation. Photon as the Quantum of Light" useful. If you did it would be great if you could spare the time to rate this physics lesson (simply click on the number of stars that match your assessment of this physics learning aide) and/or share on social media, this helps us identify popular tutorials and calculators and expand our free learning resources to support our users around the world have free access to expand their knowledge of physics and other disciplines.