244 



ELECTRICITY 



Fig. 385) the lead peroxide is not built up on a pure 

 lead plate as you made it in your experiment, but is 

 placed in the cell when it is manufactured. 



The storage battery requires considerable atten- 

 tion, and certain things in its care are very important. 

 The following rules will be helpful if you ever have 

 to care for one. 



a. Have each cell of the battery tested at least once 

 in three weeks at a battery service station. 



b. See that the plates of the cells are kept covered 

 with solution. Only pure distilled water should be 

 added. 



c. Keep all battery connections clean. 



d. Have the battery charged when the tests show 

 that recharging is needed. 



Exercise. John drove his father's car to the service 

 station to have the storage battery tested. The attendant 

 found the plates only half covered with water, but told 

 John that he would have to return later in the day as 

 he had just used his last distilled water in another bat- 

 tery. As John had learned at school that it was bad 

 for the battery to leave the plates exposed, he drove home 

 and drew some water from the city water tap and filled 

 the cells of the battery. A few days later John's father had 

 to buy a new battery. Infer a reason and establish a 

 probable cause for the old battery's failing. 



REFERENCES FOR FURTHER STUDY 

 Texts 



Caldwell and Curtis, Science for Today, Chaps. 21-22 



Clement, Collister, and Thurston, Our Surroundings, Chap. 

 IS 



Hunter and Whitman, My Own Science Problems, Unit 7 ; 

 Science in Our World of Progress, Unit 7 ; Science in Our 

 Social Life, Unit 7 



Lake, Harley, and Welton, Exploring the World of Science, 

 Chap. 23 



Pieper and Beauchamp, Everyday Problems in Science, Unit 

 14 



Powers, Neuner, and Bruner, Man's Control of His Environ- 

 ment, Unit 5 



Skilling, Tours through the World of Science, Tour 10 



Van Buskirk and Smith, The Science of Everyday Life, 

 Chap. 17 



Watkins and Bedell, General Science for Today, Chap. 23 



Webb and Beauchamp, Science by Observation and Experi- 

 ment, Unit 5 (part) 



Wood and Carpenter, Our Environment: How We Use and 

 Control It, Topic 9 



Special references 



Lunt, Everyday Electricity 

 Meister, Magnetism and Electricity 

 Darrow, Masters of Science and Invention 

 Morgan, The Boy Electrician 



WHAT YOU SHOULD AIM TO ACQUIRE FROM 

 THIS STUDY 



1. A knowledge of the early history of electricity. 



2. A knowledge of the construction, operation, care, 

 and uses of the dry cell and the storage battery. 



3. Skill in handling and connecting various types of 

 electric cells. 



4. Skill in determining the condition of a storage bat- 

 tery. 



5. A concept of electricity as a form of energy. 



TEST OF MASTERY OF TOPIC 



In your notebook complete the statements, answer the 

 questions, and comply with the instructions. 



1. The solution used in the voltaic cell is . 



2. All matter is built of (atoms, molecules) . which 



are made of 



3. are negative particles of electricity. 



4. The plate of a cell is always acted upon more by 



the solution than the plate. 



5. When rubber is rubbed with wool it is charged . 



6. In the dry cell pictured in Figure 383, the part shown 

 at A is made of _ 



7. The part shown at C contains 



8. The part shown at B is the 



plate and is made of 



9. When a glass rod is rubbed with silk it is charged 



10. The smallest particles of electricity are called 



protons. 



11. The dry cell has blotting paper in it to . 



12. A . is used to test the charge in a storage battery. 



13. is the solution used in a storage battery. 



14. The positive plate of a storage battery is made of 



15. The negative plate of a storage battery is made of 



added to them fre- 



16. Storage batteries must have . 

 quently. 



17. Write a summary of your understanding of each of 

 the three problems listed at the beginning of this topic. 



18. Lightning is electrical . that usually take place 



from to the or from cloud to 



19. City homes are less frequently struck by lightning 

 than country homes. How many reasons for this fact can 

 you suggest as possible causes? 



