ELECTRICAL APPLIANCES AND MACHINERY 271 



QUESTIONS AND EXERCISES 



1. Comb your hair rapidly with a hard rubber comb and 

 then apply the comb to some small pieces of paper or pith balls. 

 Explain what happens. 



2. Rub a glass rod with a woolen cloth or cat's fur and apply 

 the glass rod to some small pieces of paper. Observe results. 



3. Compare these results with the results produced by 

 magnets. 



4. Why are lightning rods put on tall chimneys? 



5. Where is the best place to be during a thunder storm? 

 Why? 



6. What causes electricity to flow over a wire? 



7. How many volts and amperes are used by your electric 

 lamps at home? (Volts X amperes = watts.) 



8. Examine a dry electric cell. Will it give a continuous 

 electric current very long? Why? Which pole is negative? 



9. What practical use is made of dry and wet electrical cells? 



10. How can you make an electromagnet? What practical 

 uses are made of electromagnets? 



11. Examine your electric bell and push button. Explain 

 how it works. 



12. Does a telephone carry sound? Explain. 



