Where Can I Find the Dimensional Analysis of Emissivity?

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Homework Help Overview

The discussion revolves around the concept of emissivity, specifically seeking a dimensional analysis to demonstrate that it is a dimensionless quantity. Participants are exploring the nature of emissivity as a ratio of energy emitted by materials compared to a black body.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants are questioning how to prove that emissivity is dimensionless through dimensional analysis, with references to equations involving mass, length, and time. There is also discussion about the nature of ratios and their implications for dimensionality.

Discussion Status

The conversation is ongoing, with some participants providing clarifications about emissivity being a dimensionless ratio. Others are expressing a desire to derive the formula for emissivity through dimensional analysis, indicating a productive exploration of the topic.

Contextual Notes

There is a reference to external resources, such as Wikipedia, for further information on emissivity and dimensional analysis, suggesting that participants are looking for additional context or validation of their understanding.

mikekyrou
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Homework Statement



Does anyone know where can i find (book?) the dimensional analysis of emissivity?

Homework Equations





The Attempt at a Solution

 
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hi mikekyrou! :smile:

emissivity is a dimensionless ratio (i supppose it might be better called relative emissivity)

see http://en.wikipedia.org/wiki/Emissivity" …
The emissivity of a material (usually written ε or e) is the relative ability of it's [spelling!] surface to emit energy by radiation. It is the ratio of energy radiated by a particular material to energy radiated by a black body at the same temperature. A true black body would have an ε = 1 while any real object would have ε < 1. Emissivity is a dimensionless quantity.​
 
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Thanks for the reply tiny-tim. I know what is emissivity and i want to prove that emissivity is dimensionless. I know that is because is a ratio but i want to prove it through equations(dimensional analysis-using mass,length,time).
 
but if it's a ratio of two things that are the same dimensionally, then it has to be dimensionless
 

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