1. (a) In your own words describe briefly the phenomenon of luminescence.
(b) What is the distinction between fluores- cence and phosphorescence?
2. In your own words, briefly describe the phe- nomenon of photoconductivity.
3. Briefly explain the operation of a photo- graphic lightmeter.
4. In your own words, describe how a ruby laser operates.
5. Compute the difference in energy between metastable and ground electron states for the ruby laser.