current electricity guide-doubl - infobase · current electricity 12 visual learning company...

Teacher’s Guide

Grades 5-9

Produced by:Brian A. Jerome, Ph.D.Stephanie Zak Jerome

Narrated by:Nina Keck

Production Assistant:Jessica Kassis

Visual Learning Company Visual Learning Company Visual Learning Company Visual Learning Company Visual Learning CompanyBrandon, VermontBrandon, VermontBrandon, VermontBrandon, VermontBrandon, Vermont1-800-453-84811-800-453-84811-800-453-84811-800-453-84811-800-453-8481

www.visuallearningco.comwww.visuallearningco.comwww.visuallearningco.comwww.visuallearningco.comwww.visuallearningco.com

Current

Electricity

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Visual Learning Company 1-800-453-8481

Contributors andContributors andContributors andContributors andContributors andReviewers:Reviewers:Reviewers:Reviewers:Reviewers:

Producers:Brian A. Jerome, Ph.D.Stephanie Zak Jerome, MPA

Narrator:Nina Keck

Graphics:Meredith Patch

Reviewer:Metin Yersel, Ph.D.Lyndon State CollegeLyndon, Vermont

Use and Copyright:Use and Copyright:Use and Copyright:Use and Copyright:Use and Copyright:The purchase of this video program entitles the user the right to reproduce orduplicate, in whole or in part, this teacher’s guide and the blackline masterhandouts for the purpose of teaching in conjunction with this video, CurrentElectricity. The right is restricted only for use with this video program. Anyreproduction or duplication, in whole or in part, of this guide and studentmasters for any purpose other than for use with this video program isprohibited.

The video and this teacher’s guide are the exclusive property ofthe copyright holder. Copying, transmitting or reproducing inany form, or by any means, without prior written permissionfrom the copyright holder is prohibited (Title 17, U.S. CodeSections 501 and 506).

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Table ofTable ofTable ofTable ofTable ofContentsContentsContentsContentsContents

A Message From Our Company 5

National Standards Correlations 6

Student Learning Objectives 7

Assessment 8

Introducing the Video 9

Video Viewing Suggestions 9

Video Script 11

Answers to Student Assessments 16

Answers to Student Activities 17

Assessment and Student Activities Masters 18

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The video and accompanying teacher’s guide are forinstructional use only. In showing these programs, noadmission charges are to be incurred. The programs are to beutilized in face-to-face classroom instructional settings,library settings, or similar instructional settings.

Duplication rights are available, but must be negotiated withthe Visual Learning Company.

Television, cable or satellite rights are also available, butmust be negotiated with the Visual Learning Company.

Closed circuit rights are available and are defined as the useof the program beyond a single classroom but within a singlecampus. Institutions wishing to utilize the program inmultiple campuses must purchase the multiple campus versionof the program, available at a slightly higher fee.

Discounts may be granted to institutions interested inpurchasing programs in large quantities. These discounts maybe negotiated with the Visual Learning Company.

ViewingViewingViewingViewingViewingClearancesClearancesClearancesClearancesClearances

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A Message fromA Message fromA Message fromA Message fromA Message fromour Company . . .our Company . . .our Company . . .our Company . . .our Company . . .

Dear Educator:

Thank you for your interest in the educational videos produced by theVisual Learning Company. We are a Vermont-based, family owned andoperated business specializing in the production of quality educationalscience videos and materials.

We have a long family tradition of education. Our grandmothers graduatedfrom normal school in the 1920’s to become teachers. Brian’s mother was anelementary teacher and guidance counselor, and his father was a high schoolteacher and superintendent. This family tradition inspired Brian to become ascience teacher, and to earn a Ph.D. in education, and lead Stephanie to workon science education programs at NASA.

In developing this video, accompanying teacher’s guide, and studentactivities, our goal is to provide educators with the highest quality materials,thus enabling students to be successful. In this era of more demandingstandards and assessment requirements, supplementary materials need to becurricular and standards based - this is what we do!

Our videos and accompanying materials focus on the key concepts andvocabulary required by national and state standards and goals. It is ourmission to help students meet these goals and standards, while experiencingthe joy and thrill of science.

Sincerely,

Brian and Stephanie Jerome

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National StandardsNational StandardsNational StandardsNational StandardsNational StandardsCorrelationsCorrelationsCorrelationsCorrelationsCorrelations

National Science Education StandardsNational Science Education StandardsNational Science Education StandardsNational Science Education StandardsNational Science Education Standards(Content Standards: 5-8, National Academy of Sciences, c. 1996)

Benchmarks for Science LiteracyBenchmarks for Science LiteracyBenchmarks for Science LiteracyBenchmarks for Science LiteracyBenchmarks for Science Literacy(Project 2061 - AAAS, c. 1993)

Science as Inquiry - Content Standard A:As a result of activities in grades 5-8, all students should develop:• Abilities necessary to do scientific inquiry• Understandings about scientific inquiry

Physical Science - Content Standard B:As a result of their activities in grades 5-8, all students should developan understanding of:• Transfer of Energy

The Physical Setting - Forces of Nature (4G)By the end of the 12th grade, students should know that:• There are two kinds of charges- positive and negative. Like charges

repel each other, opposite charges attract.

• Different kinds of materials respond differently to electric forces. Inconducting materials such as metals, electric charges flow easily.

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Student LearningStudent LearningStudent LearningStudent LearningStudent LearningObjectivesObjectivesObjectivesObjectivesObjectives

Upon viewing the video and completing the enclosed studentactivities, students should be able to do the following:

• Understand the various sources of electricity;

• Discuss the concept of electric potential difference;

• Define current and understand the role it plays in creatingelectricity;

• Understand the concept of resistance;

• Define Ohm’s Law and understand the relationship betweencurrent, voltage, and resistance;

• Differentiate between direct and alternating current;

• Identify the components of a circuit;

• Differentiate between series and parallel circuits;

• Understand the function of grounded plugs, fuses, andbreakers as safety features in electrical wiring; and

• Define electrical power and explain how it is calculated.s

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AssessmentAssessmentAssessmentAssessmentAssessment

Preliminary Test:Preliminary Test:Preliminary Test:Preliminary Test:Preliminary Test:

Video Review:Video Review:Video Review:Video Review:Video Review:

Post-Test:Post-Test:Post-Test:Post-Test:Post-Test:

The Preliminary Test, provided in the Student Master section, is anassessment tool designed to gain an understanding of student preexistingknowledge. It can also be used as a benchmark upon which to assessstudent progress on the objectives stated on the previous pages.

The Video Review, provided in the Student Masters section, can be used asan assessment tool or as a student activity. There are two main parts. Thefirst part contains questions titled “You Decide” that can be answered duringthe video. The second series of ten questions consists of video reviewquestions to be answered at the conclusion of the video.

The Post-Test, provided in the Student Masters section, can be utilized as anassessment tool following student completion of the video and studentactivities. The results of the Post-Test can be compared against the results ofthe Preliminary Test to assess student progress.

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Video ViewingVideo ViewingVideo ViewingVideo ViewingVideo ViewingSuggestionsSuggestionsSuggestionsSuggestionsSuggestionsYou may want to photocopy and distribute the Student Master “VideoReview”. You may choose to have your students complete this Master whileviewing the program or to do so upon its conclusion.

The program is approximately 20-minutes in length and includes a ten-question video quiz. Answers are not provided to the Video Quiz on thevideo, but are included in this teacher’s guide. You may want to gradestudent quizzes as an assessment tool or to review the answers in class.

The video is content-rich with numerous vocabulary words. For this reasonyou may want to periodically stop the video to review and discuss newterminology and concepts.

Introducing theIntroducing theIntroducing theIntroducing theIntroducing theVideoVideoVideoVideoVideo

Discuss and define the term electricity as a class. Next, dividestudents into small groups. Ask each group to list the uses ofelectricity that they see around them everyday. Ask one representativefrom each group to write the lists on the board and discuss the answersas a class. Next, ask each group to discuss some sources of electricity.Remind them to consider terms such as current, circuit, and resistance.Come together as a class and discuss the possible mechanisms behindelectricity production. Allow the lists to remain on the board duringthe video. Upon the conclusion of the program, ask students todiscuss any new information they may have learned from the video.

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Student AssessmentsStudent AssessmentsStudent AssessmentsStudent AssessmentsStudent Assessmentsand Activitiesand Activitiesand Activitiesand Activitiesand ActivitiesAssessment Masters:Assessment Masters:Assessment Masters:Assessment Masters:Assessment Masters:

• Preliminary Test

• Video Review

• Post-Test

Student Activity Masters:Student Activity Masters:Student Activity Masters:Student Activity Masters:Student Activity Masters:

• Understanding Ohm’s Law

• Electric Lemon

• Electric Safety

• Reading Electric Bills

• Electricity in Your Home

• Vocabulary of Current Electricity

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1. This large dam...

2. ...and this generating plant were built to produce power so that people...

3. ...could use electricity to light their homes,...

4. ...cook their food,...

5. ...listen to music,...

6. ...watch television,...

7. ...and do work. Electricity is the result of flowing charges. How is electricity created and how does it

travel such great distances from its source all the way to our homes?

8. During the next few minutes, we are going to see how electricity is produced. We are also going to

explore how electricity is controlled and harnessed to be useful.

9. Graphic Transition - Sources of Electric Energy

10. Have you ever wondered where the electricity you use in your home originates?

11. You may know that it comes from a wire going into your home from the street or underground.

12. But where is the source of those wires?

13. Chances are they come from some type of electrical generator station or a large power plant.

14. Most power plants use an energy source such as coal, or oil,...

15. ...or moving water to create electricity.

16. Power plants may even utilize nuclear energy in the form of enriched uranium.

17. These energy sources directly or indirectly turn generators, which in turn produce electricity.

18. But electricity can also be produced by other sources, such as batteries.

19. You have probably used batteries ...

20. ...in toys, such as this car,...

21. ...or to start an engine, such as in this car.

22. Batteries rely on chemical reactions that occur inside the battery to create electricity.

23. Another source of electricity, although less common, is photocells or solar cells.

24. These cells take light energy and convert it to electricity.

25. All of these sources work on the same principle in that they create an electric potential difference.

26. Let’s take a look at electric potential difference.

27. Graphic Transition - Electric Potential Difference

28. Electric potential difference is the amount of work required to move a charge between two points.

29. This means that whenever there is a difference in charges between two points, charges will flow from

one point to another.

30. Potential difference is measured in units called volts.

31. Voltage is the amount of energy carried by charges. The voltage in the outlets in most homes is 120

volts.

32. But for some big appliances, like clothes dryers, the voltage needs to be 220 volts.

33. Graphic Transition - Electric Current

34. What a maze of wires! This is not really that unusual. In most homes, a similar network of wires...

35. ...runs to all parts of the house, supplying electricity for lights,...

36. ...computers,...

37. ...washing machines,...

38. ...and kitchen appliances. These wires form circuits. A circuit is a wire that forms a complete path in

which both ends are connected to an electrical source.

Video ScriptVideo ScriptVideo ScriptVideo ScriptVideo ScriptCurrent ElectricityCurrent ElectricityCurrent ElectricityCurrent ElectricityCurrent Electricity

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39. Electrical charges flow through a circuit. This is often referred to as current.

40. Current is the amount of charge that flows through a point per unit of time.

41. A current consists of flowing electrons. These flowing electrons commonly are conducted in a wire.

42. Current is expressed in units called amperes or amps. An amp is the amount of charge that flows past a

point per second.

43. This instrument is an ammeter. It shows about 4.5 amps of electricity are flowing through this wire.

44. The current in a metal wire is directly proportional to the potential difference applied at the source.

45. For example, the current flow in a wire connected to a 6-volt battery would be four times that of a wire

connected to a 1.5 volt battery.

46. Graphic Transition - Resistance

47. Notice how these rocks obstruct the flow of water in this stream, causing the water to bunch up. The

rocks resist the flow of water.

48. A similar phenomenon occurs as electrons flow through a metal wire. Resistance is the opposition to

the flow of electric charge.

49. Resistance is measured in units called ohms.

50. Some materials, such as this copper wire, have very low resistance to current electricity.

51. But other materials, such as rubber, have a very high resistance to electricity and allow little or no

electricity to flow through it.

52. A simple electric light bulb operates on the principle of resistance.

53. This bulb gives off light and heat. If you have ever touched a light bulb, you know that it is often very

hot after it has been turned on for a while. Electricity often produces heat when it runs into a resistor.

54. If you look closely inside a light bulb, you will notice a thin piece of metal called the filament.

55. The filament is made of a special type of metal that acts as a resistor, converting electricity to heat and

light.

56. The same phenomenon occurs in a toaster, with the wires inside acting as resistors that produce intense

heat.

57. Graphic Transition - Current, Voltage, and Resistance

58. It is possible to compute the current in a circuit if we know the voltage and resistance.

59. A scientist by the name of George Simon Ohm did many experiments with electricity. His work led to

an understanding of the relationship between current, voltage, and resistance.

60. This is stated in Ohm’s Law, which says that current is equal to voltage divided by resistance.

61. Let’s take an example. In this circuit the voltmeter reads about .5 volts...

62. ...and the ohmmeter reads 3.5 ohms.

63. When plugged into the formula, where .5 volts are divided by 3.5 ohms, we get a current of about .14

amps.

64. Graphic Transition - Current Direction

65. Amazingly, electrons can flow through a wire in a couple different ways. One way they can move is

continuously, in the same direction.

66. This is called direct current, or DC.

63. Electricity flowing from a battery is direct current.

67. But electrons can also reverse their direction regularly, moving back and forth. This is called

alternating current, or AC.

68. The electricity that we use in our homes and schools is alternating electricity.

69. The electricity found in most homes alternates or changes direction 120 times every second!

70. Graphic Transition - Circuits

71. You Decide ! This light bulb will not light. Study the picture for a moment. What is the problem?

72. That’s right, only one post on the battery is connected.

Script (cont.)Script (cont.)Script (cont.)Script (cont.)Script (cont.)

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73. When we attach a wire to the other post, the bulb lights. This makes the circuit complete.

74. An electric circuit is a complete closed path on which an electric current flows.

75. An electric circuit has several parts. First, it must have a source of energy, such as a battery.

76. Second, it must have resistance or load, such as a light bulb. The load usually converts electricity to

light, mechanical energy, or heat energy.

77. Third, the circuit must have wires to carry the electric current.

78. Fourth, it has a switch. The switch closes and opens the circuit.

79. Electricity can only flow when the switch is on and electricity is allowed to flow. The circuit is now

closed. Electricity can only flow in a closed circuit.

80. Graphic Transition - Circuits

81. There are two main types of circuits - series circuits and parallel circuits. First, let’s take a look at series

circuits.

82. In a series circuit, there is only one way for the electrons to travel.

83. Series circuits were among the first type of electric circuits. The problem with series circuits is that if

there is a break in the circuit, the entire circuit shuts down.

84. Series circuits were among the first types of electrical circuits. The problem with series circuits is that

if there is a break in the circuit, the entire circuit shuts down.

85. This string of lights is wired in series - if one bulb is unscrewed, all of the lights in the string go out

because the circuit is open.

86. One way to solve the shortcomings of the series circuit is to use a parallel circuit.

87. In a parallel circuit, there are several paths electrons can take.

88. This is a parallel circuit with several light bulbs. If one of the bulbs were to burn out,...

89. ...notice how the others bulbs stay lit. The electrons find another path to follow and the circuit remains

closed.

90. These lights are wired in parallel. In parallel circuits, the parts of the circuit are on separate branches.

91. Graphic Transition - Circuits in Your Home

92. Believe it or not, this is what the wiring in your home looks like behind the walls.

93. This man is an electrician. His job is to safely set up electric circuits in buildings.

94. Most modern wiring looks like this, covered in a tough rubber casing.

95. Inside are three wires. The metal wires are made of copper - a very conductive metal.

96. The electric potential difference between them is 120 volts.

97. This wire is the ground wire. We will discuss the purpose of the ground wire in a minute.

98. These wires are connected to the back of an outlet, the part you usually do not see.

99. Therefore, when you plug a light into the outlet, each prong of the plug comes into contact with each

wire and makes a complete circuit.

100. Many appliances like this hand mixer have a third prong. This is the ground.

101. The purpose of the grounded plug is to protect against short circuits. A short circuit occurs when an

incorrect connection forces current to take a shorter path around a circuit.

102. If a short circuit occurs in the wire or appliance, it is grounded and the chance of being shocked is

greatly reduced.

103. Graphic Transition - Fuses and Breakers

104. Have you ever experienced a sudden loss of electricity when a lot of appliances, such as a coffee

maker, microwave, and light, were running at the same time?

105. This is a built-in safety feature in the electrical circuitry in your home.

106. The safety feature is in the metal box called a breaker box. These black switches are called breakers.

107. Breaker boxes are often located in the basement or in closets in the garage. Most homes have at least

one or two breaker boxes.


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108. When a circuit becomes overloaded, it trips the breaker and the circuit is disconnected.

109. When this happens, it is necessary to turn off the appliances and then flip the breakers back on.

110. Older homes have fuses that work in a similar way. Fuses have a small thin piece of metal through

which runs electric current.

111. When the circuit overloads and the metal strip becomes too hot - it simply melts - and the circuit is

broken.

112. The problem with fuses, however, is that they must be replaced each time they blow with a new fuse

of correct amperage.

113. Graphic Transition - Electric Power

114. Power is the rate at which work is done, or the rate at which energy is utilized.

115. Power can be applied to things that use electricity.

116. For example, this toaster has the power of about 700 watts.

117. Electric power is the rate at which electricity provides energy or does work.

118. Electric power can be computed by multiplying the voltage by the current.

119. Let’s put this formula to use by computing the electric power of the common light bulb.

120. We know that the voltage in this house is 120 volts.

121. The light bulb represents a resistance, or utilizes a current of about .33 amps.

122. When multiplied, we can see that the electric power consumed by the bulb is 40 watts.

123. If we look at the top of the bulb, we can see that is says 40 watts.

124. You Decide! Which bulb has a higher voltage?

125. That’s right! The bulb on the left has a higher voltage. It is a 75 watt bulb and is brighter that the 40

watt bulb on the right.

126. You have probably noticed meters like this on the outside or the inside of buildings. These devices

are called electric meters and measure the current of electric energy that flows into the building.

127. Notice the moving dial on the meter. It is reading the amount of electricity flowing.

128. Electric energy is the amount of power per unit time.

129. Electric energy is commonly measured in kilowatt-hours, which is 1000 watts of power used for one

hour.

130. Electric bills are based on the amount of kilowatt hours utilized over a period of time.

131. Graphic Transition - Summing Up

132. In the past few minutes we have explored current electricity.

133. We began by investigating the sources of electrical energy, such as generators....

134. ...and batteries.

135. We studied electric potential difference, as well as voltage.

136. We took a look at electrical current and current direction.

137. And we explored the concept of resistance, as well as Ohm’s Law of Resistance.

138. We also learned about different types of circuits and how they function.

139. Finally, we explored electric power and how it can be computed using a mathematical formula.

140. So the next time you use a light, work on a computer, or listen to music, take a minute to think about

how electricity affects our lives. You might just think about electrical energy a little differently.

Video Quiz

Fill in the correct word when the question appears on the screen. Good luck and let’s get started.

1. A ___________ is a device used to produce electricity.

2. Electric ________ difference is the amount of work required to move a charge between two points.


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3. A _______ is a wire that forms a complete path in which both ends are connected to an

electrical source.

4. The amount of charge that flows through a point per unit time is called ________.

5. ________ is the opposition to the flow of electric charge.

6. Resistance is measured in units called _____.

7. Electricity can only flow in a ______ circuit.

8. The third prong on an electric plug acts as the _______.

9. Breaker boxes and ______ are two safety features built into the electrical wiring of your home.

10. Electric _______ is the rate at which electricity provides energy or does work.


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Answers to StudentAnswers to StudentAnswers to StudentAnswers to StudentAnswers to StudentAssessmentsAssessmentsAssessmentsAssessmentsAssessmentsPreliminary Test1. generators2. direct3. voltage4. circuits5. current6. ampere7. resistance8. parallel9. breaker10. power11. False12. True13. False14. True15. True16. True17. False18. True19. True20. False

Video ReviewYou Decide:A. Only one post on the battery is connected.B. The bulb on the left as a higher voltage.

Post Test1. False2. False3. True4. False5. True6. True7. True8. True9. False10. True11. current12. parallel13. voltage14. circuits15. generators16. breaker17. resistance18. power19. ampere20. direct

Video Quiz:1. generator2. potential3. circuit4. current5. resistance6. Ohms7. closed8. ground9. fuses10. power

Answers to StudentAnswers to StudentAnswers to StudentAnswers to StudentAnswers to StudentActivitiesActivitiesActivitiesActivitiesActivities

Current Electricity

Understanding Ohm’s Law1. 12 ohms2. 14.7 amps3. 225 volts4. .4 amps5. 337.5 volts6. 35 ohms

Electric LemonConclusions: Yes, an electric current isproduced. Softening the lemon breaksits cellular structure apart and allowscitric acid to dissolve into a watersolution. When citric acid is in a watersolution, the hydrogen ions act aselectrolytes with the ability to conduct acurrent. Answers will vary.

Electric Safety1. False2. True3. False4. False5. False

Reading Electric Bills1. December2. September3. The temperature probably decreased and more heating appliances were probably used.

4. Temperature probably increased and more cooling appliances were used.5. 19996. It was hotter in September of 1999 - more cooling appliances were probably used.7. Electric heat, stoves and space heaters could be used to heat the home. Fans and air-conditioners could be used to cool the home.8. Answers will vary.

Electricity in Your HomeConclusions: Answers will vary. Youcan save on electricity costs by turningoff all electrical appliances when not inuse.

Vocabulary Lesson1. Ohm’s law, b2. direct current, d3. amperes, e4. electrical power, j5. alternating current, a6. series circuit, f7. current, h8. parallel circuit, g9. resistance, c10. electric circuit, i

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AssessmentAssessmentAssessmentAssessmentAssessmentand Studentand Studentand Studentand Studentand Student

Activity Activity Activity Activity Activity Masters Masters Masters Masters Masters

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Current Electricity Name___________________

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Preliminary TestPreliminary TestPreliminary TestPreliminary TestPreliminary TestDirections: Fill in the blank with the correct word. A list of possibleanswers is provided at the bottom of the page.

1. _____________ produce electricity from a variety of fuels including coal, gas, and oil.

2. When electrons move through a wire continuously in one direction, they form a ________ current.

3. __________ is the amount of energy carried by charges.

4. The mazes of wires found in most homes form ___________.

5. Electrical charge flowing through a circuit is referred to as ___________.

6. An _________ is the amount of charge that flows past a point per second.

7. A simple electric light bulb operates on the principle of ____________.

8. In __________ circuits, electrons can follow a variety of paths.

9. __________ boxes and fuses are two safety features built into the electrical circuitry in your home.

10. Electric ________ can be computed by multiplying the voltage by the current.

power ampere voltage direct circuits potential difference

current generators resistance parallel breaker closed


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PreliminaryPreliminaryPreliminaryPreliminaryPreliminaryTestTestTestTestTest

11. Potential difference is measured in watts.

12. Solar cells trap light energy from the sun and convert it to electricity.

13. Current is expressed in units called ohms.

14. Current can either be direct or alternating.

15. The greater the opposition to the flow of current, the higher the resistance.

16. The thin piece of metal inside a light bulb is called a filament.

17. Electricity can only flow in an open circuit.

18. In a series circuit, there is only one path electrons can follow.


20. Ohm’s Law states that voltage is equal to current divided by resistance.

Directions: Decide whether the answer is True (T) or False (F).

T F

T F

T F

T F

T F

T F

T F

T F

T F

T F


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Video ReviewVideo ReviewVideo ReviewVideo ReviewVideo Review

You Decide:

A. This light bulb will not light. What is the

problem?

B. Which bulb has a higher voltage?

Directions: During the course of the program answer the “You Decide”

questions as they are presented in the video. Answer the Video Quiz

questions at the end of the video.

Answer: _______________

Answer: _______________

Video Quiz:1. A ______________ is a device used to produce electricity.

2. Electric ___________ difference is the amount of work required to move a charge between two points.

3. A __________ is a wire that forms a complete path in which both ends are connected to an electrical source.

4. The amount of charge that flows through a point per unit time is called ___________.

5. ______________ is the opposition to the flow of electric charge.

6. Resistance is measured in units called ____________.

7. Electricity can only flow in a ___________ circuit.

8. The third prong on an electric plug acts as the ___________.

9. Breaker boxes and __________ are two safety features built into the electrical wiring of your home.

10. Electric __________ is the rate at which electricity provides energy or does work.


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Post TestPost TestPost TestPost TestPost TestDirections: Decide whether the answer is True (T) or False (F).

1. Current is expressed in units called ohms.

2. Ohm’s Law states that voltage is equal to current divided by resistance.


4. Electricity can only flow in an open circuit.

5. The thin piece of metal inside a light bulb is called a filament.

6. The greater the opposition to the flow of current, the higher the resistance.

7. Current can either be direct or alternating.

8. In a series circuit, there is only one path electrons can follow.

9. Potential difference is measured in watts.

10. Solar cells trap light energy from the sun and convert it to electricity.

T F

T F

T F

T F

T F

T F

T F

T F

T F

T F


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Post TestPost TestPost TestPost TestPost TestDirections: Fill in the blank with the correct word. A list of possibleanswers is provided at the bottom of the page.

11. Electrical charge flowing through a circuit is referred to as ________.

12. In __________ circuits, electrons can follow a variety of paths.

13. __________ is the amount of energy carried by charges.

14. The mazes of wires found in most homes form ___________.

15. _____________ produce electricity from a variety of fuels including coal, gas, and oil.

16. __________ boxes and fuses are two safety features built into the electrical circuitry in your home.

17. A simple electric light bulb operates on the principle of ____________.

18. Electric ________ can be computed by multiplying the voltage by the current.

19. An _________ is the amount of charge that flows past a point per second.

20. When electrons move through a wire continuously in one direction, they form a ________ current.

power ampere voltage direct circuits potential difference

current generators resistance parallel breaker closed


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Understanding Ohm’sUnderstanding Ohm’sUnderstanding Ohm’sUnderstanding Ohm’sUnderstanding Ohm’sLawLawLawLawLawBackground:Chances are you have turned on a light bulb today and watched it glow withlight. Have you ever wondered how a light bulb gives off light? Light bulbsoperate on the principle of resistance. Resistance is a material’s oppositionto the flow of electrons. A light bulb contains a thin piece of metal calledthe filament that acts as a conductor. As a current flows through thefilament, it encounters resistance and the electromagnetic energy isconverted to light and heat energy. The light energy results in the light wesee and the heat energy is what causes the light bulb to become very hot.All conductors have a certain amount of resistance.

Scientist George Simon Ohm did a series of experiments to determine therelationship among current, resistance, and voltage. Ohm’s Law states thatthe current in a wire equals the voltage divided by the resistance.

Current (amps) = Voltage (V) Resistance (ohms)

Directions: Using the information provided above, complete the followingchart. You may use the back of this page for your calculations.

Amps Volts Ohms

10 120

250 17

15 15

12 30

7.5 45

5 175


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Electric LemonElectric LemonElectric LemonElectric LemonElectric LemonObjective:In this lab you will create electricity using a lemon, zinc pieces, and copper wire.

Background:The electricity we use in our homes is produced by generators in power plants. But didyou know that electricity can be produced by something as simple as a lemon and somepocket change? You have all probably tasted the bitterness of a lemon. This is caused bycitric acid. When dissolved in water, acids will split apart to form hydrogen ions. Anelectrolyte is a substance that can conduct an electric current when in a water solution.When the lemon in this experiment is softened, the citric acid will break down intohydrogen ions, thus becoming a conductor of electric current.

Materials:VoltmeterLemonTwo pieces of zinc (or two pennies)Copper wireScissors

Procedure:1. Wrap the copper wire around each piece of zinc. Place the zinc pieces about 1 inch apart.2. Connect each end of the wire to the voltmeter. One end should be connected to the positive terminal and the other to the negative terminal. Make sure the voltmeter is on.3. Soften a lemon by rolling it back and forth on a surface while exerting a bit of pressure with the palm of your hand. Using a pair of scissors, slice two slits in the lemon, approximately the same size as the zinc pieces. Caution: Be careful not to cut yourself!4. Slip each zinc piece into its own slit.5. Record the voltage measured by the voltmeter.6. Switch the wire connections to the voltmeter and record the new voltage.

Conclusions:Is an electric current produced? What is accomplished by softening the lemon? Howdoes the lemon conduct a current? Is there any difference in voltage when the wireconnections are switched?


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Electric SafetyElectric SafetyElectric SafetyElectric SafetyElectric SafetyBackground:Electricity is an important source of energy in our everyday lives. It isalso a very dangerous resource and must be respected by following a fewbasic ground rules. First, electricity should never be used in the directvicinity of water. The presence of water could result in electrocution as aresult of the formation of an electrical circuit. You should never approachfallen power lines since these wires often conduct high voltages. Wiresshould never be allowed to remain frayed or worn. Frayed wires couldresult in short circuits and fires if found near or under a carpet. Alwayskeep fingers or other objects away from electric sockets. Electricity couldbe conducted through whatever object is in the socket or even directly intoyour finger and through your body. Finally, the number of appliancesconnected to a socket should correspond to the socket’s potential. Fuseswill fail if this potential is exceeded and electricity can be temporarily lost.

Directions: Decide whether the following statements are True (T) or False(F) based on the information provided above.

1. It is dangerous to blow dry your hair if it is raining outside.

2. It is unsafe to connect all the appliances in your home to one socket.

3. It is perfectly safe to stick a spoon in an electrical socket.

4. It is safe to hide all the wires in a room by running them under a rug.

5. It is safe to pick up an object that is lying next to a fallen power line.

T F

T F

T F

T F

T F


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Reading Electric BillsReading Electric BillsReading Electric BillsReading Electric BillsReading Electric Bills

Billing Period KWH used Billing Days Avg Temperature

September 1999 626 33 75

September 1998 452 29 66

Directions: Use the information provided below to answer the questions on thefollowing page.

Background:Each month you receive an electric bill that charges you for the amount ofelectricity your home has used in the previous month. But do you know what allthe information on that bill means? First, there is a billing portion where thenumber of kilowatt-hours used is multiplied by a base rate, usually about 10cents per kilowatt-hour, give or take a few cents. This gives you your monthlyelectricity costs. Also included in an electric bill is a section that allows you tocompare your electricity use throughout the year. This section will include amonthly comparison for the previous year as well as a comparison between thepresent month and that same month one year earlier. This information can helpcustomers understand increases in bills as well as trends in their use ofelectricity. The data below is for a house located in northern New England.

12 Month Comparison

KWHper month

Month


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Reading Electric BillsReading Electric BillsReading Electric BillsReading Electric BillsReading Electric Bills1. During which month were the most kilowatt-hours used?

2. During which month were the least kilowatt-hours used?

3. List some possible reasons why electricity use increased from November to December.

4. List some possible reasons why electricity use increased during the months of June and July.

5. Was more electricity used in September of 1999 or September of 1998?

6. List some possible reasons why more electricity was used in your answer to number 5.

7. What are some common appliances used to heat your homes in the winter and cool your homes in the summer?

8. Brainstorm some possible ways to cut down on heating and air-conditioning use in your homes.


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Electricity in YourElectricity in YourElectricity in YourElectricity in YourElectricity in YourHomeHomeHomeHomeHomeObjective:In this activity you will learn how to approximate the amount of electricity used bycertain appliances in your home.

Background:Most of us have numerous electrical appliances in our homes, such as arefrigerator, a television, a hair-dryer, or a light bulb. Using these appliances is notfree. An electric bill comes each month, charging you for the amount of electricityyou have used. Every appliance has a power rating measured in units called watts.This power rating can be used to calculate the amount of electricity used by thatappliance. The equation used to calculate the amount of energy used by anappliance in one day is as follows:

Energy (kWh) = power (kW) x time (h)

The current electricity rate is approximately 10 cents per unit, or kilowatt-hour.You can calculate the cost of using an appliance by multiplying the kilowatt-hoursused by the cost per unit.

Procedure:1. Pick five electrical appliances that you use in your household daily. Record the power rating of each of these appliances. This number may be found on the back of the appliance.2. Estimate the number of hours per day that you use each of these appliances.3. Create a data chart including sections for the name of each appliance, the hours of use, power ratings, the energy used, and the daily cost of each appliance.4. Using the equation above, calculate the amount of energy in kilowatt-hours used by each appliance and the cost of using that appliance for one day. Complete you data chart by placing these calculations in the appropriate column.

Conclusions:Which appliance uses the most energy? Is this the result that you expected? Whatare some possible ways to save on electricity costs in your home?


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Vocabulary of Vocabulary of Vocabulary of Vocabulary of Vocabulary of CurrentCurrentCurrentCurrentCurrentElectricityElectricityElectricityElectricityElectricityDirections: Unscramble the following vocabulary words and match eachword with its correct definition.

___ 1. mohs’ wla

___ 2. tcride rrtucne

___ 3. apsemre

___ 4. leclaertic oprwe

___ 5. lngtaeraitn ntrucre

___ 6. sierse turicci

___ 7. trenruc

___ 8. lllrpaae trcciui

___ 9. ssceneirta

___ 10. cletecri uiccrti

a. current in which electrons regularlyreverse their direction of flow

b. states that current is equal to voltagedivided by resistance

c. opposition to the flow of electriccharge

d. current in which electrons flow inone continuous direction

e. amount of charge that flows past apoint per second

f. circuit in which electrons have onlyone path to follow

g. circuit in which electrons have morethan one path to follow

h. the flow of electric charge

i. a complete closed path on which anelectric current flows

j. the rate at which electric powerprovides energy or does work

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