Much of the interaction of light with matter can be understood using two
ideas;
1. Energy reflected + energy transmitted + energy absorbed = incident
energy
or
R + T + A = 1
2. Kirchoff's Law:
Energy emitted = energy absorbed
or emissivity = absorptivity
For an opaque material (T=0),
R + A = 1
so
A = 1 - R
So materials with high reflectivity have low absorptivity, and hence low
emissivity.
Larry Woolf
General Atomics
www.ga.com
www.sci-ed-ga.org
-----Original Message-----
From: Bernard Cleyet
Sent: Tuesday, February 06, 2007 3:56 PM
Subject: [Phys-l] Emissivity and conductivity.
While researching IR on that other list, I discovered tabulated the IR
emissivity of very many materials. My quick anecdotal study leads me to
believe (excluding surface roughness) that good conductors have low
emissivity and visa versa. this is, of course, opposite to
reflectivity, whose classical explanation is more than a century old
(Drude).