[/caption]In the last few centuries, in which time we have had several scientific revolutions, our understanding of heat, energy and the exchange thereof has grown exponentially. In particular has been the increasing ability to gauge the amounts of energy involved in particular processes and in turn create theoretical frameworks, units, and even tools with which to measure them. One such concept is the measurement known as Emissivity. Essentially, this is the relative ability of a material’s surface (usually written ? or e) to emit energy as radiation. It is expressed as the ratio of the emissivity of the material in question to the radiation emitted by a blackbody (an idealized physical body that absorbs all incident electromagnetic radiation) at the same temperature. This means that while a true black body would have an emissivity value of 1 (? = 1), any other object, known as a “grey body”, would have an emissivity value of less than 1 (? Engineering Toolbox and Science World.
We’ve also recorded an entire episode of Astronomy Cast all about Electromagnetism. Listen here, Episode 103: Electromagnetism.
References:
http://en.wikipedia.org/wiki/Emissivity
http://en.wikipedia.org/wiki/Absorptance
http://en.wikipedia.org/wiki/Black_body
http://www.thefreedictionary.com/emissivity
http://www.monarchserver.com/TableofEmissivity.pdf
The JWST is astronomers' best tool for probing exoplanet atmospheres. Its capable instruments can dissect…
First light for the Vera Rubin Observatory (VRO) is quickly approaching and the telescope is…
A beautiful nebula in the southern hemisphere with a binary star at it's center seems…
The history of astronomy and observatories is full of stories about astronomers going higher and…
The JWST keeps one-upping itself. In the telescope's latest act of outdoing itself, it examined…
You've seen the Sun, but you've never seen the Sun like this. This single frame…