1. Briefly explain what determines the characteristic color of (a) a metal and (b) a transparent nonmetal.
2. Briefly explain why some transparent materials appear colored while others are colorless.
Opacity and Translucency in Insulators
3. Briefly describe the three absorption mechanisms in nonmetallic materials.
4. Briefly explain why amorphous polymers are transparent, while predominantly crys- talline polymers appear opaque or, at best, translucent.