Introduction to Electricity

Transcription

1 CHAPTER 17 DIRECTED READING WORKSHEET Introduction to Electricity As you read Chapter 17, which begins on page 420 of your textbook, answer the following questions. Strange but True! (p. 420) 1. Which of the following is NOT true about electric eels? a. An electric eel uses electric discharges to stun or kill its prey. b. The body of an adult eel can generate 5,000 to 6,000 V. c. The eel s thick skin protects it from electrocuting itself. d. Eels swallow their prey whole. 2. The bursts of voltage that an eel gives off when it shocks its prey is greater than the voltage of an electrical outlet. True or False? (Circle one.) CHAPTER Section 1: Electric Charge and Static Electricity (p. 422) 4. When you shuffle your feet on the carpet on a dry day, you get a shock from the metal objects that you touch. What is the cause of this? DIRECTED READING WORKSHEETS 123

2 Atoms and Charge (p. 422) Choose the word in that best matches the description in 5. composed of atoms 6. a positively charged particle of the nucleus 7. a negatively charged particle found outside the nucleus 8. a particle of the nucleus that has no charge a. proton b. neutron c. matter d. electron 9. According to the law of electric charges, like charges attract and opposite charges repel. True or False? (Circle one.) 10. Why don t electrons fly out of atoms while traveling around the nucleus? 11. Which of the following does NOT determine the strength of an electric force between charged objects? a. the age of the charges b. the size of the charges c. the distance between the charges d. All of the above contribute. 12. The region around a charged particle that can exert a force on another charged particle is called the. Charge It! (p. 424) Choose the word in that best matches the definition in 13. wiping electrons off of one object onto another 14. transfer of electrons when one object touches another object 15. rearranging electrons in an uncharged object when it is near a charged object a. induction b. friction c. conduction 124 HOLT SCIENCE AND TECHNOLOGY

3 16. When objects are charged, charges cannot be created or destroyed. True or False? (Circle one.) 17. An electroscope can determine which of the following? a. whether or not an object is charged b. the material that a charged object is made of c. the strength of the charge on an object d. how many electrons are involved in the charge Moving Charges (p. 426) 18. Electric cords are often covered in plastic and have metal prongs. This is because metal is a good and plastic is a good. CHAPTER Hair dryers should not be used near water. Why? Static Electricity (p. 427) 20. What is static electricity? a. an electric charge on a stationary object b. random electric signals from your dryer c. the buildup of electric charges on an object d. electricity that moves away from an object 21. As charges move off an object, the object loses its static electricity. This process is called electric. 22. How does clothing that has become charged in a dryer lose its charge? 23. An electric discharge can occur quickly or slowly. True or False? (Circle one.) DIRECTED READING WORKSHEETS 125

4 24. Standing on a beach or golf course during a thunderstorm can make you like a lightning rod. Why? Section 2: Electrical Energy (p. 430) 1. Name something that uses electrical energy that would be difficult for you to live without. Explain. Batteries Are Included (p. 430) Choose the word in that best matches the definition in 2. converts chemical energy into electrical energy 3. type of cell that contains a solid or pastelike electrolyte 4. mixture of chemicals in a cell 5. where charges enter or exit a cell 6. type of cell that contains a liquid electrolyte a. electrode b. cell c. electrolyte d. wet e. dry Bring on the Potential (p. 431) 7. In a battery, electric current exists between the two electrodes because there is a difference in between the electrodes. 126 HOLT SCIENCE AND TECHNOLOGY

5 CHAPTER 17 DIRECTED READING WORKSHEET Introduction to Electricity As you read Chapter 17, which begins on page 420 of your textbook, answer the following questions. Strange but True! (p. 420) 1. Which of the following is NOT true about electric eels? a. An electric eel uses electric discharges to stun or kill its prey. b. The body of an adult eel can generate 5,000 to 6,000 V. c. The eel s thick skin protects it from electrocuting itself. d. Eels swallow their prey whole. 2. The bursts of voltage that an eel gives off when it shocks its prey is greater than the voltage of an electrical outlet. True or False? (Circle one.) What Do You Think? (p. 421) Answer these questions in your ScienceLog now. Then later, you ll have a chance to revise your answers based on what you ve learned. CHAPTER 17 Investigate (p. 421) 3. What is the purpose of this activity? The purpose of this activity is to make electrically charged objects and observe their effect on other objects. Section 1: Electric Charge and Static Electricity (p. 422) 4. When you shuffle your feet on the carpet on a dry day, you get a shock from the metal objects that you touch. What is the cause of this? The shock is caused by a buildup of static electricity, which is discharged when you touch metal. DIRECTED READING WORKSHEETS 123

6 Atoms and Charge (p. 422) Choose the word in that best matches the description in c a d b 5. composed of atoms 6. a positively charged particle of the nucleus 7. a negatively charged particle found outside the nucleus 8. a particle of the nucleus that has no charge a. proton b. neutron c. matter d. electron 9. According to the law of electric charges, like charges attract and opposite charges repel. True or False? (Circle one.) 10. Why don t electrons fly out of atoms while traveling around the nucleus? Protons and electrons have opposite charges, and therefore they attract each other. 11. Which of the following does NOT determine the strength of an electric force between charged objects? a. the age of the charges b. the size of the charges c. the distance between the charges d. All of the above contribute. 12. The region around a charged particle that can exert a force on another charged particle is called the electric field. Charge It! (p. 424) Choose the word in that best matches the definition in b c a 13. wiping electrons off of one object onto another 14. transfer of electrons when one object touches another object 15. rearranging electrons in an uncharged object when it is near a charged object a. induction b. friction c. conduction 124 HOLT SCIENCE AND TECHNOLOGY

7 16. When objects are charged, charges cannot be created or destroyed. True or False? (Circle one.) 17. An electroscope can determine which of the following? a. whether or not an object is charged b. the material that a charged object is made of c. the strength of the charge on an object d. how many electrons are involved in the charge Review (p. 426) Now that you ve finished the first part of Section 1, review what you learned by answering the Review questions in your ScienceLog. Moving Charges (p. 426) 18. Electric cords are often covered in plastic and have metal prongs. This is because metal is a good conductor and plastic is a good insulator. CHAPTER Hair dryers should not be used near water. Why? Tap water conducts charges very well, so if you accidentally drop the hair dryer in water, you might receive an electric shock from charges travelling through the water. Static Electricity (p. 427) 20. What is static electricity? a. an electric charge on a stationary object b. random electric signals from your dryer c. the buildup of electric charges on an object d. electricity that moves away from an object 21. As charges move off an object, the object loses its static electricity. This process is called electric discharge. 22. How does clothing that has become charged in a dryer lose its charge? The electric charges are transferred to water molecules in the air. 23. An electric discharge can occur quickly or slowly. True or False? (Circle one.) DIRECTED READING WORKSHEETS 125

8 24. Standing on a beach or golf course during a thunderstorm can make you like a lightning rod. Why? Beaches and golf courses tend to be flat and have few tall objects to attract lightning. Lightning will be attracted to a person because he or she is the tallest object in the area. Review (p. 429) Now that you ve finished Section 1, review what you learned by answering the Review questions in your ScienceLog. Section 2: Electrical Energy (p. 430) 1. Name something that uses electrical energy that would be difficult for you to live without. Explain. Accept any reasonable answer. Sample answer: Refrigerators would be very difficult to live without because keeping food fresh would be more difficult. Batteries Are Included (p. 430) Choose the word in that best matches the definition in b e c a d 2. converts chemical energy into electrical energy 3. type of cell that contains a solid or pastelike electrolyte 4. mixture of chemicals in a cell 5. where charges enter or exit a cell 6. type of cell that contains a liquid electrolyte a. electrode b. cell c. electrolyte d. wet e. dry Bring on the Potential (p. 431) 7. In a battery, electric current exists between the two electrodes because there is a difference in charge between the electrodes. 126 HOLT SCIENCE AND TECHNOLOGY