CURRENT ELECTRICITY
From
Electricity and Magnetism
A Unit of Study
Produced by
Colgren Communications
Written by
John Colgren
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Table of Contents
Introduction . . . . . . . . . . . . . . . . . . . . . . .1
Instructional Notes . . . . . . . . . . . . . . . . .1
Links to Curriculum Standards . . . . . . . . .2
Student Objectives . . . . . . . . . . . . . . . . .3
Assessment Tools . . . . . . . . . . . . . . . . . . .3
Unit Test . . . . . . . . . . . . . . . . . . . . . . . . .3
Teacher Preparation . . . . . . . . . . . . . . . . .4
Introducing the Program . . . . . . . . . . . . .4
View the Program . . . . . . . . . . . . . . . . . . .4
Discussion Questions . . . . . . . . . . . . . . . .4
Description of Blackline Masters . . . . . . .5
Enrichment Activities . . . . . . . . . . . . . . . .6
Answer Key . . . . . . . . . . . . . . . . . . . . . . . .6
Internet Resources . . . . . . . . . . . . . . . . .10
Script of Narration . . . . . . . . . . . . . . . . .10
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CURRENT ELECTRICITY
from
Electricity and Magnetism A Unit of Study
Grade Levels: 5-8
Viewing Time: 15 minutes
INTRODUCTION
This live-action program is designed for use with the intermediate grade levels (5-8).
This program is about current electricity. There are two types
of electricity: static and current. Current electricity is the energy we use in our homes, schools, and businesses to run all of
our appliances and electronic devices.
INSTRUCTIONAL NOTES
Before presenting this lesson to your students, we suggest that
you preview the program and review this guide and the accompanying blackline master activities in order to familiarize yourself with their content.
As you review the materials presented in this guide, you may
find it necessary to make some changes, additions, or deletions
to meet the specific needs of your class. We encourage you to
do so, for only by tailoring this program to your class will they
obtain the maximum instructional benefits afforded by the
materials.
It is also suggested that the program presentation take place
before the entire group under your supervision. The lesson
activities grow out of the context of the program; therefore, the
presentation should be a common experience for all students.
1
LINKS TO CURRICULUM STANDARDS
This Unit of Study addresses the following National Science
Education Standards for grades 5-8:
Science as Inquiry
Content Standard A:
• Abilities necessary to do scientific inquiry
Plan and conduct simple investigations.
Employ simple equipment and tools to gather data.
Use data to construct a reasonable explanation.
Communicate investigations and explanations.
• Understanding about scientific inquiry
Physical Science
Content Standard B:
• Energy is a property of many substances and is associated
with heat, light, electricity, mechanical motion, sound, nuclei,
and the nature of a chemical. Energy is transferred in many
ways.
• Electrical circuits provide a means of transferring electrical
energy when heat, light, sound, and chemical changes are produced.
Science and Technology
Content Standard E:
• Abilities of technological design
• Understanding about science and technology
People have always had questions about their world.
Science is one way of answering questions and explaining
the natural world. People have always had problems and
invented tools and techniques to solve problems.
Scientists and engineers often work in teams.
Tools help scientists make better observations, measurements, and equipment for investigations.
History and Nature of Science
Content Standard G:
• Science as a human endeavor
Science and technology have been practiced for a long time.
Men and women have made a variety of contributions
throughout the history of science and technology.
2
Although men and women using scientific inquiry have
learned much about the objects, events, and phenomena in
nature, much more remains to be understood. Science will
never be finished. Many people choose science as a career
and devote their entire lives to studying it.
STUDENT OBJECTIVES
After viewing the program and participating in the lesson activities, the students should be able to do the following:
• Define current electricity.
• Define the three parts of a complete circuit.
• Define and differentiate between conductors and insulators.
ASSESSMENT TOOLS
This lesson provides you with three different assessment tools.
Together they make it possible to closely follow the progress of
your students and to judge their mastery of the subject matter.
The Pre-Test (Blackline Master 1) can be used to get some
idea of students' understanding of the topic before the program
is presented.
The Post-Test (Blackline Master 11) can be used as a final test
for the lesson.
The Program Quiz and its accompanying answer sheet
(Blackline Master 2) can be used either as a way to introduce
the topic prior to showing the program or to judge student mastery once the program has been presented.
UNIT TEST
An optional Unit Test has been provided with this lesson. It can
be used as a final test to gauge student comprehension of the
material presented in all five lessons of this Unit of Study.
Answers to the Unit Test are provided in the Answer Key of this
instructor’s guide.
3
TEACHER PREPARATION
View the program and review the accompanying activities.
Duplicate any blackline masters you wish to distribute. If you
plan to use the Program Quiz, which immediately follows the
program presentation, you may wish to have copies of the quiz
ready to distribute at the completion of the program. Also, plan
to pause the tape between questions if students require more
time.
INTRODUCING THE PROGRAM
Remind students that there are two different kinds of electricity: static and current. Static electricity is electrical charges that
build up on something and then jump to something else.
Current electricity is electricity that flows and is the kind we
use to run all our many appliances and devices. Current electricity must have a complete circuit on which to travel. The circuit is made of a source of electricity, a path for the electrons to
travel along, and a device to use the electrons.
VIEW THE PROGRAM
Viewing time for this program is 15 minutes. The program quiz
that follows the presentation will take about three minutes when
you build in pauses for recording answers.
DISCUSSION QUESTIONS
You may wish to conduct a discussion after viewing the program based on the following:
1. Ask students to recall the three parts of a complete circuit.
2. Review the reasons why certain elements make excellent
conductors of electricity.
3. Discuss the differences between series and parallel circuits.
4
DESCRIPTION OF BLACKLINE MASTERS
This program contains 11 blackline masters that can be used to
reinforce ideas and information presented in the program.
• Blackline Master 1, Pre-Test, provides a way of measuring
how much students know about the material covered in this lesson before you present it. Students’ scores on the Pre-Test can
be compared with their scores on the final Post-Test (Blackline
Master 11).
• Blackline Master 2, Program Quiz, is to be used at the end
of the program. At the completion of the program, there is a
short quiz. The narrator will read the questions which are displayed on the screen. Students can use Blackline Master 2 to
record their answers. Answers to the questions are provided in
the Answer Key section of this instructor's guide.
• Blackline Master 3, Is It A Conductor Or An Insulator?, is
an experiment to test different objects and determine whether
they are conductors or insulators.
• Blackline Master 4, Incandescent Bulb, describes the makeup of an incandescent bulb. Students are asked to write an
experiment for setting up a circuit to light a flashlight bulb.
• Blackline Master 5, Three-Way Bulb, shows an illustration
of a regular incandescent bulb and a three-way bulb. Students
are asked to describe how a three-way bulb works.
• Blackline Master 6, Galvanometer, is an experiment asking
students to build a galvanometer.
• Blackline Master 7, Simple Circuit, challenges students to
think of different ways to light flashlight bulbs.
• Blackline Master 8, Simple Circuit 2, asks students to predict whether a sketch of a bulb, dry cell, and wire will work as
a complete circuit causing the bulb to light. Then students
should try the set-ups to see if their predictions were correct.
5
• Blackline Master 9, Circuits, discusses the two types of circuits: series and parallel.
• Blackline Master 10, Gates, shows three simple switches
that can be used to control the flow of electricity in a circuit.
• Blackline Master 11, Post-Test, is an evaluation tool for this
unit.
ENRICHMENT ACTIVITIES
1. Bring in some old electric appliances and motors to disassemble. Provide an opportunity for students to analyze how
these objects work.
2. Have some interested students find out how television works.
ANSWER KEY
• Blackline Master 1, Pre-Test
A.
1. d 2. g 3. a
4. c
5. f
6. b
7. e
B.
1. A series circuit has one path on which the electricity travels.
If more than one bulb or appliance is connected in series and
one of the devices burns out, all the devices will turn off. In a
parallel circuit, there is more than one path for the electrons to
travel along; so if one appliance burns out, it doesn't affect the
others in the circuit.
2. A parallel circuit would have to be used in household circuits,
or else every time something burned out, everything in that circuit would also turn off.
3. These metals are elements which have loosely held electrons
in their outer electron shells.
• Blackline Master 2, Program Quiz
1. c
2. d
3. b
4. a
5. c
6
• Blackline Master 3, Is It A Conductor Or An Insulator?
Answers will vary.
• Blackline Master 4, Incandescent Bulb
Description of wiring the light bulb will vary.
• Blackline Master 5, Three-Way Bulb
The bulbs are different from each other in that the three-way
bulb has an extra metal ring on its base.
The three-way bulb has two filaments. One is 50 watts and the
other is 100 watts. The switch can be turned to different settings, which send electricity to the metal contacts in the bulb
base. One setting sends electricity to the central contact, which
turns on the 50-watt filament. Another setting sends electricity
to the outer metal ring of the base. This lights up the 100-watt
filament. Finally, a third switch setting sends electricity to both
contacts in the base, which turns on both filaments for a total of
150 watts.
• Blackline Master 6, Galvanometer
1. Moving the magnet in and out of the coil creates a flow of
electricity. The compass dial will move from side to side, showing an example of alternating current.
2. The compass needle will move, but this is direct current, so
it won't alternate back and forth.
• Blackline Master 7, Simple Circuit
1. The light bulb will light up if the end contact and the silver
metal, or threaded part, of the base each have separate contact
with the wire and the battery terminal.
2. Both bulbs will only light if each bulb is arranged in a way
that allows contact with the end contact and the silver metalthreaded parts of the bulbs. They will light even if one bulb is
touching the other.
The ceramic material is used in the bulb base to insulate the end
contact from the metal base. The ceramic material is a good
insulator, so it stops the flow of electrons. As you can see in the
drawing, the filament goes from the end contact and then to the
metal-threaded area.
7
The two important parts of the bulb are the end contact and the
metal-threaded area. The filament is connected to both so a
complete circuit can be made.
• Blackline Master 8, Simple Circuit 2
1. will light
5. will not light
2. will not light
6. will light
3. will light
7. will light
4. will not light
8. will not light
• Blackline Master 9, Circuits
1. In a parallel circuit, the other bulb remains lit.
2. Both lights go out.
Conclusions: The series circuit has only one path on which the
electrons can travel. The parallel circuit has more than one path
for the electrons.
• Blackline Master 10, Gates
If students have constructed the three gates properly, they will
work as intended.
• Blackline Master 11, Post-Test
1. A source of electrons, a path for the electrons, and something
to use the electrons.
2. A conductor is a material that will allow electrons to flow
easily through it.
3. An insulator is a material that resists the flow of electrons.
4. A series circuit has only one path for electrons to travel. If
something within the circuit burns out, everything in the circuit
will go out.
5. A parallel circuit has more than one path for the electrons, so
if something burns out, the other devices in the circuit continue
to receive electricity.
6. A circuit breaker will stop the flow of electrons if the circuit
is overloaded.
7. A parallel circuit is used to prevent all appliances to go out if
one burns out.
8. A short circuit happens if a wire carrying a flow of electricity is torn and the electricity has a path into the ground or some
other conductor. A short circuit can be very dangerous.
8
9. Current electricity is electricity that is flowing. It is produced
at power plants or obtained from batteries and dry cells.
10.
battery
• Unit Test
I. Matching
1. d
2. h
3. f
4. a
5. i
6. g
7. c
8. e
9. b
II. Short Answer
1. copper, silver, gold
2. wood, glass, rubber, cloth, plastic
3. Insulators are used to stop the flow of electricity. Insu-lators
around a wire will stop the electricity from moving out of the
wire and into another conductor.
4. A generator produces electricity. It is made of either a coil of
wire spinning in a magnetic field or a magnet spinning in a coil
of wire. In either case, a flow of electrons is created.
5. An electromagnet can be made with a source of electrons,
some wire, and an iron nail. Wrap the wire around the nail.
Connect the wire ends to the terminals of the battery and you
have an electromagnet.
6. An electromagnet can be turned on and off, but a regular bar
magnet can't.
7. A source of electrons, a path for the electrons to flow along,
and something to use the electrons.
8.
battery
battery
9
9. A series circuit has one path on which electricity flows. If a
bulb in a series circuit burns out, all the lights go out. A parallel circuit has two paths on which the electricity flows. If one
bulb burns out, there is still a path for the electricity to flow
along, so other bulbs in the circuit stay lit.
10. Fuses and circuit breakers will automatically trip, or stop,
the flow of electricity if the circuit becomes overloaded by the
flow of current.
11. Answers will vary.
12. The sun's energy through the use of solar cells, wind turbines, geothermal energy, chemical energy.
13. They would move apart because they would be re-pelled.
14. They would come together because they are attracted.
15. a. 4 amps
b. 8 amps
c. 6 amps
INTERNET RESOURCES
The following websites may be valuable sources of additional
information to reinforce the objectives of this lesson:
1. "What Is Electricity?" by Energy Information Administration.
http://www.eia.doe.gov/kids/electricity.html
2. Clark County Public Utilities in the state of Washington has
a wonderful site with excellent pages on topics related to electricity.
http://clarkpud.apogee.net/kids/
3. Energy Story at the Energy Quest Site.
http://www.energyquest.ca.gov/story/index.html
SCRIPT OF NARRATION
There are two types of electricity, static and current.
Current electricity is the flow of electrical charge. To move
from one place to another, current electricity needs what is
called a complete circuit. The circuit is made up of three things.
10
There must be a source of electrons, something to use the electrons, and a path for the electrons to travel along to go to the
device and back to the source. Here is a simple circuit that is
made up of a battery, some wire, and a light bulb. When the
path for the electrons to travel along is complete then the bulb
will light. This is called a closed circuit. There are no breaks,
or gaps, in the circuit. When there is a break in the circuit, it is
called an open circuit. The path isn’t complete and the electrons can’t flow.
For the circuit to work, there must be wires that will conduct
electricity as part of the path. Conductors are substances that
allow electricity to flow through them easily.
You can make a conductor detector with a battery, light bulb,
and some wire. Test some things that you think might conduct
electricity. Copper is an excellent conductor; that’s why most
wire is made from copper. Zinc is a good conductor and so are
silver and gold. In fact, silver and gold are excellent conductors of electricity, better than copper and zinc.
Expensive audio and video equipment often uses gold-plated
cables and plugs because gold is such a good conductor.
Other things aren’t good conductors. They are called insulators, which means they resist, or stop, the flow of electricity.
Wood is an insulator and so is plastic. Wires have plastic coatings that help keep the current from moving out of the wire.
Some insulators are used in electrical devices such as this toaster oven. The wire that turns red and heats the food is resisting
the flow of electrons, and, as a result, it is heating up. This wire
is used to specifically cook the food.
You may wonder why zinc, copper, and gold are such good conductors.
Let’s look at the periodic table of elements to find the answer.
Notice that the three metals we are talking about are located
here on the table. To see why these metals are good conductors,
we need to look at their atomic structure.
11
Let’s look at copper first. Copper is element 29, which means
it has 29 protons and 29 electrons in each atom.
Electrons are found in orbit around the nucleus of an atom. The
nucleus is made up of protons and neutrons.
The electrons in orbit will fill up orbital shells. These shells are
specific distances from the nucleus. Each shell can hold a certain number of electrons. The first shell can hold two electrons
and the next shell can hold eight electrons. That makes ten
electrons so far. The next shell can hold as many as 18 electrons. So the total electrons in the first three shells comes to 28,
which leaves one electron left in the copper atom. That lone
electron will be by itself in the fourth electron shell. Because it
is all by itself, it is easily bumped out of orbit if another free
electron comes near by and repels it. This repulsion happens
because the two electrons each have a negative charge.
Zinc is a good conductor because it is element number 30. It
has thirty electrons and therefore, two electrons in the fourth
shell. These two electrons are loosely held.
Silver is element 47. It has 47 electrons: two in the first shell,
eight in the second shell, eighteen in the third shell, eighteen
in the fourth shell for a total of 46 electrons. That leaves one
electron in the fifth shell. Yes, it is a loosely held electron.
SERIES AND PARALLEL
There are two kinds of circuits. One is called a series circuit
and the other is called a parallel circuit. Let’s look at a series
circuit first.
Here is a simple series circuit that is made up of a source of
electrons, something to use the electrons, and a path for the
electrons to travel along. We can add another bulb to the series
circuit and both will light up. Notice however, that they are
dimmer than the one bulb by itself. Now watch what happens
when we unscrew one bulb and cause a break in the circuit path.
Both lights go out. For the series circuit to work, everything
must be connected without any breaks, or gaps, in the circuit.
12
The parallel circuit is set up differently. There are additional
pieces of wire used to connect the two bulbs. This time, when
the bulb in one holder is loosened, only that bulb turns off. The
other light stays on. This happens because there is more than
one path for the electrons to travel along. This is called a parallel circuit because the wires form parallel lines. If one path is
interrupted, there is still another path for the electrons to travel
along.
Which type of circuit would you guess is used in common
household circuits? Well, if you said a parallel circuit, you’re
right. If household circuits were built in series, then the television would go off when the light bulb burns out. However,
because that doesn’t happen, we know that parallel circuits are
used.
A switch can be very helpful in a circuit. The switch can control when electrons will flow. When the switch is closed, the
circuit is complete and electricity flows. When the switch is
open, the flow of electricity stops.
CIRCUIT BOX
Circuits in a house, store, or school must be protected. They
must be protected from overheating. Circuit boxes are used to
provide this protection. When the electrical lines come into the
building, they go to the circuit box. The box splits the main line
into several smaller circuits. Each circuit is capable of carrying
a certain flow of electrons.
If too many things are plugged into a circuit and they are all
being used at the same time, it may cause a problem. As more
and more current is sent through the circuit, the wires begin to
get hot and will possibly start a fire. So to protect against this
happening, the circuit is tripped. That means the path is interrupted and the flow of electrons stops. Many people get mad
when this happens, but they should actually be happy because
it means the circuit breaker is doing its job and preventing a
possible fire.
To get the circuit working again, you should unplug and turn off
some of the things plugged into the circuit and then the circuit
breaker can be flipped back on.
13
In many bathrooms and kitchens, you will find a special outlet
called a ground fault circuit interrupter, or GFCI. This outlet
works like a circuit breaker in a circuit box to protect us from
electrical shock. It constantly compares the current in one side
of the outlet with the current in the other side. If there is a difference, it opens the circuit so electricity stops flowing. To
regain use of the outlet, you must push in the reset button.
THOMAS EDISON AND THE LIGHTBULB
One of the greatest inventors of all time was Thomas Edison.
He established the first industrial research laboratory in world
history. He built a two-story lab and additional buildings to
house teams of craftsmen and tools to carry on scientific investigations and research. He brought together craftsmen in a wide
variety of fields, from glass blowers to machinists and from
chemists to mathematicians.
Thomas Edison and his team came up with many inventions
that have had a great impact on the world. They are responsible for the phonograph, movie projector, improvements on the
telephone, and telegraph. In fact, Edison had 1,093 patents by
the time he died. He and his team of researchers at Menlo Park
averaged a new patent or invention every eleven days.
Edison didn’t invent the incandescent bulb, but he did develop
the first successful light bulb. This is often considered his most
important contribution. The main problem was finding a material that could be used as a filament. Incandescent bulbs make
light by using electricity to heat a thin strip of material so hot
that it glows. They needed something that would resist the flow
of electrons and glow. But finding a material that would do that
and not burn up was a very hard task. They tried grass, hair, and
all kinds of fibers coated with different chemicals. No one
knows for sure how many things Edison tried before discovering that bristol board, which is a kind of thin cardboard, coated
with carbon would work. However, when asked, Edison admitted that he knew of fourteen thousand ways not to make a light
bulb.
Edison powered his light bulbs with wet and dry cells and eventually a generator.
14
Here is one of the first houses equipped with Edison’s light
bulb. He set up many of the buildings and this home on the
grounds of Menlo Park, his research center, with lights and
electricity for a demonstration of this new invention. Notice
how the wires are exposed and travel along the ceiling. Also,
notice the wood used as supports and insulators.
Not long after this demonstration, Edison built the first power
plant. He wired a block with electric lights in New York City.
Edison’s system included dynamos, switches, electric meters,
fuses, distribution lines, and regulators. He didn’t invent the
incandescent light bulb, but he was the first person to make one
that worked. His breakthrough with the electric light led to all
the wonderful uses we make of electricity today.
SUMMARY
Today we have taken a look at current electricity. Electricity is
the flow of electrons. There are two types of electricity: static
and current. Static electricity is electricity that builds up on an
object and remains on that object until there is a place for it to
go. Lightning is an example of static electricity. Current electricity is the flow of a charge through a conductor. Current electricity is the electricity we use to run things at home, school,
and at work.
Current electricity is generated at huge power plants and sent to
our homes. Or we buy some batteries at the store and use them
to power our toys and utensils. For electricity to flow, there
must be what is called a complete circuit. That means there
must be a supply of electrons, a path for the electrons to travel
along, and something to use the electrons. The circuit must be
complete, or closed, for the electrons to move. If the circuit is
open, then electrons can’t flow through the circuit.
There are two different kinds of circuits. They are called series
and parallel. A series circuit has one path for the electrons to
travel along, so if something in the path becomes burned out or
disconnected, the entire circuit is affected. A parallel circuit has
parallel wires for the electricity to flow through, so if one light
burns out, the others stay lit. It takes more wire to make a parallel circuit, but it is worth it to avoid having a circuit fail
because of one bulb or appliance going out.
15
Electricity is one of our most important forms of energy. Our
lives are greatly affected when electricity isn’t available or for
some reason stopped.
Now it is time for the program quiz. There are five multiple
choice questions.
1. Current electricity is _______________.
a conductor
an insulator
the flow of electrons
a closed circuit
2. A complete circuit is made of three things:
an insulator, a source of electrons, and a path
a conductor, a source of electrons, and a path
a switch, a source of electrons, and a path
something to use the electricity, a source of electrons,
and a path
3. Something that allows electrons to flow easily through it is
called _________.
an insulator
a conductor
a switch
a current
4. Something that slows the flow of electrons is called
_________.
an insulator
a conductor
a switch
a current
5. There are two types of circuits called ____________.
insulators and conductors
closed and open
series and parallel
switch and current
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