Image Credit: glassessential.com
[/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
A supermassive black hole in the heart of a galaxy is the ultimate 800-pound gorilla…
Deflecting potentially hazardous asteroids (PHAs) is one of humanity's most critical long-term efforts to ensure…
It turns out that you don't need the Men in Black to spot unidentified anomalous…
Earth releases about as much energy out into space as it absorbs, arriving at a…
The quest to understand dark matter has taken many twists and turns. It's a scientific…
If the Sun has a stellar neighbourhood, it can be usefully defined as a 20…