Blackbody Radiance Homework: Calculating Warming & Cooling Rates

In summary, the conversation discusses a problem involving a slab of matter between two infinite planes with a distance of 1m apart. The absorption coefficient is 1m2kg-1, density is 1kgm-3, and heat capacity is 103^3jk-1kg-1. It is assumed that the absorption coefficient is independent of wavelength. The first question asks for the rate at which the slab would warm up by absorbing incident radiance from a source emitting blackbody radiation at 300K. The second question involves computing the irradiance emitted by the slab and the rate at which it would cool by emission, assuming it is also at 300K. The third question asks for the equilibrium temperature of the slab if
  • #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 The Attempt at a SolutionI know i'm supposed to use the Stefan-Boltzmann law for this problem and find the net rate at which energy is gained or lost. But i don't know what other formulas or laws I should use.
 

What is blackbody radiance?

Blackbody radiance refers to the electromagnetic radiation emitted by a perfect blackbody, which is an object that absorbs all radiation that falls on it and emits radiation in all wavelengths.

Why is calculating warming and cooling rates important?

Calculating warming and cooling rates helps us understand the rate at which heat is transferred between objects and their surroundings. This is important for understanding climate change and the Earth's energy balance.

How do you calculate warming and cooling rates?

Warming and cooling rates can be calculated using the Stefan-Boltzmann law, which states that the rate of heat transfer (in watts) from a blackbody is proportional to the fourth power of its absolute temperature.

What factors affect blackbody radiance?

The factors that affect blackbody radiance include temperature, emissivity, and the surface area of the object. Higher temperatures result in higher radiance, while higher emissivity and larger surface area result in lower radiance.

Can blackbody radiance be used to predict the temperature of an object?

Yes, blackbody radiance can be used to predict the temperature of an object, as long as the emissivity and surface area are known. By measuring the radiance of an object, its temperature can be determined using the Stefan-Boltzmann law.

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