Emissivity of radiation from a surface, Leslies cube

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SUMMARY

The discussion centers on the emissivity of thermal radiation as demonstrated by Leslie's cube, highlighting the differences in radiation emission between surfaces. Black surfaces, with an emissivity of 1, emit the most radiation due to their ability to absorb energy effectively, while silver surfaces reflect energy, resulting in low emissivity. The symmetrical nature of absorption and emission processes explains why good absorbers are also good emitters. The inquiry also touches on the practical advantages and disadvantages of using Leslie's cube in everyday situations.

PREREQUISITES
  • Understanding of black body radiation and emissivity concepts
  • Familiarity with Leslie's cube and its experimental setup
  • Basic knowledge of thermal radiation principles
  • Concept of energy absorption and reflection in materials
NEXT STEPS
  • Research the principles of black body radiation and its significance in thermodynamics
  • Explore the concept of emissivity in different materials and its applications
  • Investigate the practical uses of Leslie's cube in educational demonstrations
  • Learn about the advantages and disadvantages of thermal radiation in real-world applications
USEFUL FOR

Students studying thermodynamics, educators demonstrating thermal radiation concepts, and anyone interested in the practical applications of emissivity in everyday life.

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Homework Statement



Hello! I am going to do a demonstration involving the Leslie's cube to demonstrate the emissivity of a thermal radiation from different surfaces. I have been reading some about black body radiation which has emissivity = 1 but this is not the case. Leslie's cube has 4 surfaces but could someone explain to me why the black surface emitts the most of the radiation and the silver one least?

Thank you!



Homework Equations





The Attempt at a Solution


 
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Black surfaces absorb, silver or white surfaces reflect.

The absorption and emission processes are symmetrical. This means a good absorber is a ready emitter.

For the white or silvet surface pretend the energy to be emitted is just inside the cube. The silver surface will reflect the energy back into the box, so low emissivity.
 
yes I know that but I would like to know what is the physical explanaition for it? what makes that the black one emitts the most? why it has the highest emissivity ?
 
i just did experiment on Leslie's cube, but can not often answer 1 question: which says, what is the advantage and disadvantage of my device in every day life situation. can someone please help me with this!
 

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