I do a similar lab, but run it twice: once in clear water and once in water with black India ink powder. The first time most of the light gets out, while most of the IR is absorbed. The second time both light and IR are absorbed. It makes a good case against using incandescent lamps for lighting. (although they are good heat sources)
Skip Kilmer
Greenhill School
-----Original Message-----
From: phys-l-bounces@carnot.physics.buffalo.edu [mailto:phys-l-bounces@carnot.physics.buffalo.edu] On Behalf Of Richard Taylor
Sent: Saturday, August 25, 2007 8:25 AM
To: Forum for Physics Educators
Subject: Re: [Phys-l] heat labs?