Blackbody Radiance: Calculate Absorption & Emission Rates & Equilibrium Temp

In summary, to solve this problem, you will need to use the Stefan-Boltzmann law and the given properties of the slab to calculate the rates of energy absorption and emission, and then use these to find the equilibrium temperature.
  • #1
beasht
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Homework Statement





Consider a slab of matter contained within two infinite planes a distance of s = 1m apart.
absorption coefficent =1m2kg-1
density of slab 1kgm-3
heat capacity 103^3jk-1kg-1
assume the absorption coefficient to be independent of wave length

1.Suppose one face of a slab is illuminated by a source emitting blackbody radiation at temp 300k, compute the rate at which the slab would tend to warm up by absorption of incident radiance.
2. assuming the slab is also at temp of 300k compute the irradiance emitted by the slab. Compute the rate at which the slab would tend to cool by emission.
3. assuming that the incident black body radiation remains unchanged in time, compute the temp at which the slab will come into equilibrium.


justing looking for some pointers to get started such as formulas, etc that are best suited for this problem, and guidance on the steps i need to take,
any info much appreciated,
thanks
 
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  • #2
Homework Equations Stefan-Boltzmann Law: I=σT^4 The Attempt at a Solution1. To find the rate at which the slab will warm up, you will need to use the Stefan-Boltzmann law to calculate the irradiance of the incident radiation. Then, you can use the absorption coefficient, density and heat capacity of the slab to compute the rate of energy absorbed by the slab. 2. To calculate the rate at which the slab cools by emission, you will again need to use the Stefan-Boltzmann law to calculate the irradiance emitted from the slab. Then, you can use the absorption coefficient, density and heat capacity of the slab to compute the rate of energy emitted. 3. To calculate the equilibrium temperature, you will need to set the rate of energy absorbed by the slab equal to the rate of energy emitted by the slab. Then, you can solve for the equilibrium temperature.
 

1. What is blackbody radiation?

Blackbody radiation refers to the electromagnetic radiation emitted by a theoretical object that absorbs all radiation that falls on it. It is a type of thermal radiation that is emitted by all objects with a temperature above absolute zero.

2. How is blackbody radiation related to absorption and emission rates?

The absorption and emission rates of blackbody radiation refer to the amount of energy absorbed and emitted by the object, respectively. These rates are dependent on the temperature of the object and follow the laws of thermodynamics.

3. How can the equilibrium temperature of a blackbody be calculated?

The equilibrium temperature of a blackbody can be calculated using the Stefan-Boltzmann law, which states that the total energy emitted by a blackbody is proportional to the fourth power of its temperature. This law can be used to calculate the equilibrium temperature at which the absorption and emission rates are equal.

4. What factors affect the absorption and emission rates of a blackbody?

The absorption and emission rates of a blackbody are affected by its temperature, the material it is made of, and its surface area. Generally, higher temperatures and larger surface areas result in higher rates of absorption and emission.

5. How is blackbody radiation used in scientific research?

Blackbody radiation is used in several fields of science, including astrophysics, thermodynamics, and materials science. It is used to study the properties of materials and understand the behavior of objects in extreme environments, such as stars and other celestial bodies.

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