Talk:Thermal emittance

Untitled

Is this right? It looks to me as though this is confusing emittance with emissivity, switching between the two all the way through the article. I thought that:

Emissivity is where the body is compared to a black body (comparing its radiation against black body radiation.

Emittance is the total flux emitted per unit area, presumably at a specificed temperature. It will of course depend on emissivity, but unlike emissivity will have units. I'm not a physicist though. Probably best to ask one of them. 155.198.69.221 (talk) 07:04, 25 September 2008 (UTC)

corrections made. my gut reaction was to replace this with a redirect, but then I realized that many non-physicists are unaware that heat is electromagnetic radiation, so they would get confused by the redirect. -- 99.233.186.4 (talk) 06:05, 18 November 2009 (UTC)

Conflicting Definitions

I believe this article could use some clarification. Boyd defines Radiant Exitance as symbol M, with units of W/m² (I'll edit with the the full reference later); granted this may be specific to radiometry. In A.F. Mills Heat Transfer, 2nd Ed., Emittance is is defined as the fraction of of blackbody emissive power, lowercase epsilon. In the Mills text he writes "emittance" followed by "or emissivity" in parenthesis, which to me indicates interchangeability. He footnotes this statement with the following:

"Both the endings -ance and -ivity are commonly used for radiation purposes. In this text, -ance will be used for surface radiation properties. In Chapter 6, -ivity will be used for gas radiation properties."

Is this definition refined in a later edition of Mills' text (I only have 2nd edition on hand)? Maybe there should be a table with a breakdown by industry- physics, radiometry, heat transfer, etc.? Mollynet (talk) 21:00, 21 April 2010 (UTC)