ASTR 503 Homework 4 : Properties of Light

This activity requires a diffraction grating (either in special slides or as special diffraction glasses, available from "Rainbow Symphony". Special punch-out spectroscopes are available from the Stanford Solar Center. I will provide one for every teacher registered for audit or CEU credit, and a full classroom set for each teacher registered for full credit. If you did this in class as an activity, please only do two more sources of the printed activity (#2) and use the printout to sketch in the lines you observed in class.

1. Assemble the spectroscope per the directions. Or if you don't have a spectroscope, just use the diffraction glasses or a diffraction slide. Holding a white card in front of the spectrum (to the side left or right) makes the spectrum more visible. If you hold (or mount) the slide with the longer edge horizontally, the spectrum will appear to the right AND to the left of the source image. For the slides I provide, if you can read the writing, it is the correct way up.

2. Do the "Colors of light" activity from "Space Update". The pdf can be downloaded "A href="http://www.spaceupdate.com/activities/AS02_colors_of_light.pdf"> by clicking here.

If you use the spectroscope, try to estimate the wavelength of the brightest lines observed from each of the sources.
You can (approximately) calibrate your wavelength scale by putting on the provided scale on the back so you see it through the spectroscope (to the right as you are holding it). The bright red line of Hydrogen is called H-alpha. Its wavelength is 656.28 nm.
We will have several sources available in class, but there are others listed on the activity sheet that can be used. Observe at least two more sources besides those viewed in class and make pencil marks for each of the lines, or shading for bands of light. Be sure to answer the questions on the sheet. Note when you look at stoplights or tail lights, can you tell from the spectrum which are incandescent and which are LEDs? How does an LED tail light look compared to an (older) incandescent tail light?

_____________________________________

Last updated 2/9/2022