Over the years I have found it useful to demonstrate to students the relationship of color to wavelength in spectrometers. Even many of the seniors are delighted and a bit surprised at the particular correspondence of color and wavelength. To facilitate this demonstration I have used three devices which I will illustrate for a B&L Spectronic 20. First, and leastsatisfactory, is simply to drop a piece of thin paper approximately 1em X 2.5 cm into a dry cuvet in the spectrometer well. Second, one may take a piece of white chalk, 2.5 cm long, and rub one end to obtain a 45' angled face. The chalk is then dropped into the cuvet with the 4 5 O face up and oriented towards the wavelength dial on the instrument. For both of these methods the colors are ohserved by peering into the well. The third, and most dramatic, demonstration involves obtaining a piece of Y-in. Lucitee rod 10 em in length and a 3/&. i.d. O-ring. One end of the rod is cut a t a 45" angle and polished; the other is given a "ground glass" finish by rubbing with sand paper. The O-ring is then put on the rod one crn from the ground end and the rod is then placed, angled end down, in a cuvet in the spectrometer well. The cuvet is then rotated to give maximum intensity at the ground end.
Richard A. Paselk Humboldt State University Arcata, CA 95521
Volume 59
Number 5
May 1982
383
