Electricity
Transcription
Electricity
Name Date Electricity Before You Read Before you read the chapter, respond to these statements. 1. Write an A if you agree with the statement. 2. Write a D if you disagree with the statement. Before You Read Work and Machines • Electrical forces act at a distance. • Electric charges can be created and destroyed. • All circuits contain electrical resistance. • Electricity can flow only through an open circuit. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Construct the Foldable as directed at the beginning of this chapter. Science Journal List five devices that use electrical energy. Write the forms of energy into which electrical energy is converted by each device. Accept all reasonable responses. Possible answers: lamp—light energy and thermal energy; hair dryer—thermal energy and kinetic energy; toaster—thermal energy; TV—light and sound; CD player—sound Electricity 67 Name Date Electricity Section 1 Electric Charge Skim Section 1 of your book. Write three questions that come to mind from reading the headings and the illustration captions. 1. Accept all reasonable responses. 2. 3. Review Vocabulary Use your book to define gravity. gravity attractive force between two objects that depends on the masses of the objects and the distances between them New Vocabulary Read the definitions below. Write the key term that matches each static electricity law of conservation of charge electric field conductor the buildup of electric charge on an object charge can be transferred, but not created or destroyed a region of force around an electric charge within which other charges are attracted or repelled a material in which electrons are able to move easily insulator a material in which electrons are not able to move easily charging by contact the process of transferring charge by touching or rubbing charging by induction electroscope electrons on a neutral object are moved by a charged object a device that detects electric charge Academic Vocabulary Use a dictionary to define the term create. create 68 Electricity to bring into existence Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. definition in the left column. Name Date Section 1 Electric Charge Charges Exert Forces I found this information on page . (continued) Model charges and electric fields of two items that have just been removed from a clothes dryer. Accept all reasonable responses. SE, p. 171 RE, p. 91 Encourage clear and logical drawing rather than artistic merit. Suggest that students use different colors to represent positive and negative charges. I found this information on page . Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. SE, p. 172 RE, p. 92 Conductors and Insulators I found this information on page . SE, p. 173 RE, p. 93 Encourage students to identify objects in the classroom as conductors or insulators. Compare the force of electricity to the force of gravity. Provide examples to complete the table. Accept all reasonable answers. Location of Force Force Example Within an atom Electricity The attraction between the electron and proton of a hydrogen atom. Between atoms Electricity The attraction between the hydrogen and oxygen in water. Between objects Gravity The attraction between me and my book. Between objects Electricity The attraction between my feet and the carpet after I scuff my feet on it. Classify five conductors and five insulators in the correct space below. Conductors Insulators Accept all reasonable responses. Students should include various metallic objects. Accept all reasonable responses. Students should include various paper, wood, plastic, and glass objects. Electricity 69 Name Date Section 1 Electric Charge Charging Objects I found this information on page . SE, pp. 174–175 RE, pp. 93–94 (continued) Describe the type of charging that occurs in each event. 1. Lightning strikes a lightning rod on a tall building. Charging by induction; Separated charges within a cloud rearrange the electrons on nearby Earth. 2. The lightning rod moves excess charges to Earth’s surface. Charging by contact; The charged lightning rod transfers charge to Earth, which it is touching. I found this information on page . SE, pp. 176–177 RE, p. 94 Sequence the events that occur when an electroscope is used to detect a charge on an object. 1. A negatively 2. Electrons (or positively) travel charged down (or up) the object rod. touches the knob at the top of beaker. 3. Both leaves 4. The leaves gain negative (or positive) charges. repel each other and spread apart. C ONNECT I T Hypothesize what might happen if you use electrical appliances while standing or sitting in water. Accept all reasonable responses. Water is a conductor. If you were to drop an electrical appliance into water when it is plugged in, electric charge would be conducted through the water. If you were in that water, the charge would then be conducted through you, causing injury or death. 70 Electricity Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Electroscopes