2. Has frictional electricity industrial importance?
3. What is a Leyden jar?
4. Does frictional electricity cause any danger? Explain.
5. How may this danger be removed?
6. Describe an electric neutralizer.
7. For what are humidifiers used in mills?
8. Describe lightning.
9. What dangers are attached to it?
10. Name the different forms of lightning.
11. Explain the relation of thunder to lightning.
12. What is a lightning rod?