Lesson: Thermal RadiationPhysics
In this lesson, we will learn how to use the Stefan–Boltzmann law to calculate the intensity of thermal radiation emitted by an object of a given temperature.
Sample Question Videos
An infrared heater for a sauna has a surface area of 0.050 m2 and an emissivity of 0.84. What temperature must it run at if the required power is 360 W? Neglect the temperature of the environment. Where Stefan-Boltzman constant = .
The intensity of the radiation of sunlight at a distance from the Sun of km is measured to be 2.6 kW/m2.
Calculate the radiative power of the Sun.
Calculate the radius of the Sun. Use a value of K for the Sun’s temperature and use a value of 1.0 for the Sun’s emissivity.
Thermal radiation from the Sun has an intensity of about 600 W/m2 at the radius of Mars’s orbit. Assume the Sun is a perfect sphere and its temperature is uniform. Ignore any greenhouse effects.
Assuming the Sun’s rays are parallel, Find the area that must be multiplied by to get the total radiation intercepted by Mars. Use a value of 3,400 km for the radius of Mars.
Find the temperature at which Mars radiates energy at the same rate. Assume that at the infrared wavelengths where it radiates, the emissivity e is 1.00.