Charge Transfer Diagrams

Transcription

1 + + = CHAPTER 7 BLM 33 Charge Transfer Diagrams Goal Review your understanding of charge transfer Use the following diagram to answer question 1 3 Use ( ) to represent negative charges and (+) to represent positive charges 1 The diagram shows represents a neutral solid object What is the relationship between the number of positive and negative charges in a neutral object? must in They equal amount 2 When the above neutral object is rubbed with a material, it becomes positively charged (a) Draw a new diagram that represents the object with a positive charge t + + (b) How do the number of positive charges compare to the original diagram? more He charges Way compared To the original diagram (c) How do the number of negative charges compare to the original diagram? Much less ve charges compared To the Original diagram 3 When the neutral object is rubbed with a different material, it becomes negatively charged (a) Draw a new diagram that represents the object with a negative charge we + = = = (b) How do the number of positive charges compare to the original diagram? Much less tve charges compared To the original diagram (c) How do the number of negative charges compare to the original diagram? more way charges compared To the original diagram Copyright 2007, McGrawHill Ryerson Limited, a subsidiary of the McGrawHill Companies All rights reserved This page may be reproduced for classroom use by the purchaser of this book without the written permission of the publisher

2 E CHAPTER 7 Obeying the Laws of Static BLM 35 Charge Goal Review your understanding of the laws of static charge Complete the following sentences using the following terms Each term may be used more than once attracts, repels, positive, neutral, negative 1 A negative charged is repelled by a negative charge 2 A positive charge a Attracts negative charge 3 A charged object a attracts neutral object 4 A negative object attracts an unknown object The unknown object could be or neutral positive 5 A positive object repels a positive object Use the diagram below to answer question 6 Table is neutral A positively charged object is attached to a table as shown Use an arrow to indicate the direction of the force on the negative ( ), positive (+), and neutral (no sign) charges placed near the object on the table 7 Use the words increased or decreased to complete each of the following statements (a) To increase the electric force between two charged objects, the distance separating the two charges should be decreased (b) To increase the electric force between two charged objects, the amount of charge on one or both objects should be increased (c) To decrease the electric force between two charged objects, the distance separating the two charges should be increased (d) To decrease the electric force between two charged objects, the amount of charge on one or both objects should be decreased Copyright 2007, McGrawHill Ryerson Limited, a subsidiary of the McGrawHill Companies All rights reserved This page may be reproduced for classroom use by the purchaser of this book without the written permission of the publisher

3 CHAPTER 7 BLM 38 Forces and Electrical Charges Goal Review your knowledge of electric charge and its interaction with conductors, insulators, and electroscopes Answer the questions that follow 1 Classify the following items using an X Human body Air Wood Rubber Plastic Aluminum Silver Wool Copper Iron Fur Conductor Insulator 2 Using the list of words below, complete the following sentences Each word may be used more than once negative, negatively, positive, positively, opposite (a) opposite charges are unlike charges (b) Two like charges are either both tve or both re X (c) If two opposite charges are brought together, they will be attracted : (d) If a tray charged object is brought near a positively charged electroscope, the leaves will separate (e) If a charged balloon X very is brought near a positively charged rod, the balloon is attracted to the rod 3 The diagram below shows two charged pith balls hanging on thin threads One ball in each diagram is shown with either a positive (+) or a negative ( ) charge The arrows indicate whether the two balls are attracted or repelled On the diagram, indicate the charge on the blank balls (a) (b) (c) t + Copyright 2007, McGrawHill Ryerson Limited, a subsidiary of the McGrawHill Companies All rights reserved This page may be reproduced for classroom use by the purchaser of this book without the written permission of the publisher

4 CHAPTER 7 BLM 311 Chapter 7 Quiz Goal Check your understanding of Chapter 7 Circle the letter of the best answer 1 Static electricity refers to charges that A travel through a conductor B eist on a neutral object C can be collected and held in one place D power your computer 2 Which of the following correctly identifies the charges on the particles of an atom? Proton Electron Neutron A positive neutral negative B negative positive neutral C neutral negative positive D positive negative neutral 3 Which of the following statements describes a solid neutral object becoming positively charged? A Protons have been removed from this object B Electrons have been removed from this object C Protons have been added to this object D Electrons have been added to this object 4 A object that contains 5 million electrons can still be neutral because A electrons have no charge B the electrons are spread out evenly in the object C it also contains 5 million protons D the object is an insulator 5 Static charge can apply a force without touching the other object This type of force is called A actionatadistance force B long distance force C contact force D imaginary force Copyright 2007, McGrawHill Ryerson Limited, a subsidiary of the McGrawHill Companies All rights reserved This page may be reproduced for classroom use by the purchaser of this book without the written permission of the publisher

5 BLM 311 continued 6 Which of the following is true of charged objects? A Like charges attract and opposite charges repel B Like charges repel and neutral objects are repelled by charged objects C Like charges repel and opposite charges attract D Like charges attract and neutral objects are attracted to charged objects 7 Which of the following would increase the force between two charged objects? A increasing the distance between the objects B increasing the charge on the objects C decreasing the charge on the objects D none of the above 8 Which of the following best describes a neutral solid object that is charged by conduction? A The electrons in the neutral solid object relocate when a charged object is brought near B The protons in the neutral solid object relocate when a charged object is brought near C The electrons in the neutral object transfer onto a positively charged object D The protons in the neutral object transfer onto a negatively charged object 9 Which of the following best describes a neutral solid object that is charged by induction? A The electrons in the neutral solid object relocate when a charged object is brought near B The protons in the neutral solid object relocate when a charged object is brought near C The electrons in the neutral object transfer onto a positively charged object D The protons in the neutral object transfer onto a negatively charged object 10 An electroscope that is charged positive would have its metal leaves separated A negatively charged rod is brought close to, but not touching the knob of the positive electroscope The metal leaves would A move farther apart B move closer together C not move D become negatively charged Copyright 2007, McGrawHill Ryerson Limited, a subsidiary of the McGrawHill Companies All rights reserved This page may be reproduced for classroom use by the purchaser of this book without the written permission of the publisher

6 Bring BLM 311 continued Match the Term on the left with the best Descriptor on the right Each Descriptor may be used only once Term 11 electroscope 12 Van de Graaff generator :F 13 acetate A 14 conductor D 15 grounding B 16 coulomb Descriptor A materials that allow electrons to travel freely B the unit of electric charge C device used to produce large amounts of static charge D allowing charge to flow into Earth s surface E materials that do not allow electrons to travel freely F device used to detect static charge G acquires a negative charge by friction Short Answer Questions 17 Two charged objects are positioned 5 cm away from each other Describe the change in the force between these two objects when (a) the charge on one of the objects is increased force increases (b) the distance between the objects is increased to 10 cm (c) the charge on both of the objects is decreased force force decreases decreases Use the following diagram of a neutral solid object to answer question Use ( ) to represent electrons and (+) to represent protons to complete the diagrams (a) A positive rod is positioned near the original object IF I (b) A positive rod is touched to the original object The Styrofoam chips used for packing often have a static charge and cling to you Describe how you could use an acetate strip to determine whether the Styrofoam chips are positively or negatively charged Charge the acetate by rubbing WI paper towel the negatively charged acetate near the styrofoam chips If the positively charged chips attract then it is, Copyright 2007, McGrawHill Ryerson Limited, a subsidiary of the McGrawHill Companies All rights reserved This page may be reproduced for classroom use by the purchaser of this book without the written permission of the publisher