electric circuits lesson plan

8/11/2019 Electric Circuits Lesson Plan

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SIMPLE ELECTRICCIRCUITS

K-STATE RESEARCH AND EXTENSION- SEDGWICK COUNTY7001 W. 21st St. North

Wichita, KS 67205-1759(316) 722-7721

FAX (316) 722-7727

[email protected]://www.sedgwickcountyextension.org


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Cooperative Extension ServiceSedgwick CountyExtension Education Center7001 W. 21stSt. NorthWichita, KS 67205-1759316-722-7721FAX 316-722-7727

HOME PAGEhttp://www.oznet.ksu.edu/sedgwick


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SIMPLE ELECTRIC CIRCUITSSuggested Grades: 4thand 5th

Electricity is caused by the movement of the electrons that are present in all atoms.Static electricity results from electrons jumping or transferring short distances from oneobject to another in a random fashion. Static electric charges only build up on objectsthat have electrons that do not move easily such as plastic, rubber, and nylon.

Current electricity results from a orderly flow of electrons that move easily along a pathof conductivematerial, much like the movement of water through a pipe or hose. Thepath that electrons follow is called an electric circuit. The circuit usually includes threemain parts: (1) a source of electrical energy that supplies electrons, such as a battery;

(2) an object that makes use of the electricity, such as a light bulb; and (3) a conductorthat connects everything together, usually metal wire.

Batteries are often used as a source of electrical energy. The chemicals in a batteryreact with each other to cause a buildup of electrons on the negative (-) end of thebattery. This movement of electrons leaves positively charged particles at the positive(+) end of the battery. This difference in electrical pressure or potential between the twobattery ends is called voltage.

Because of the way a battery is constructed, the positive and negative charges thatwould normally be attracted to each other are kept separated. When an outside

connection links the two ends, the negatively charged electrons flow towards thepositively charged end of the battery.

An uninterrupted path through which electrons flow is called a complete or closedcircuit. If a circuit includes more than one path, electrons will go through all of theavailable paths. A large number of observations by scientists has shown that there is asimple set of rules that determines how much current follows each path.


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If an electrical circuit is broken or interrupted the current cannot flow and the path iscalled an open circuit. Sometimes a circuit is broken accidentally when a wire is looseor a bulb burned out. Often, though, circuits are opened intentionally with an on-offswitch. This allows people to switch off lights at bedtime, set a furnace thermostat tostay warm, or use the memory of a computer to play a favorite game.

Electrons will only flow if there is apotential difference; a source of available negativeelectrons that can be attracted to an area of positive charge. The flow of electricity issomewhat similar to the flow of water through a hose. In order for the water to flow,there needs to be a difference in pressure between the ends of the hose. Water ispushed from the high pressure end (the faucet) toward the low pressure end (thenozzle). In an electric circuit, electrons flow from the negative pole of the battery througha conductor to the positive pole of the battery.

Conductors provide the path for the electrons to follow from the negative pole to thepositive pole of the battery, just as a hose forms the path for water to flow through from

the faucet to the nozzle. Some materials are easier for electrons to move through freelyand evenly without accumulating in one place. These materials are called conductors.Most good conductors are metal or metal alloys.

Materials that are poor conductors of electrons are called insulators. Electrons do notmove freely through these materials, so they are often used to cover the outside ofelectric wires or electrical equipment. Insulators are nonmetals; rubber, wood, glass,cloth, or plastics.

How are circuits formed and used?

What materials make the most effective electrical circuits?

OBJECTIVES

Students will construct parallel and series circuits and explain how each type ofcircuit works

Students will describe the qualities that define good and poor conductors ofelectricity and will list at least three of each type of conductor


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MATERIALS

Lamp Demonstration1 old lamp that can be taken apart

Flashlight Circuit Analysis1 flashlight for each activity grouppaper and pencil for each student

Simple Circuit Making Activity1 copy of Simple Circuit DataSheet for each student (p 18)

1 D-cell battery (mercury free, ifpossible) for each activity group

2 strips of aluminum foil, about 1cm (112 in.) wide and 12-15 cm (5-6 in.) long for each activity groupAlternative: 2 pieces of insulatedcopper wire, 12-15 cm (5-6 in.)long

1 flashlight bulb (about a 3-voltrating) for each activity group

1 pen or pencil for each student

Optional (to help hold the circuitcomponents together): 2 strips ofmasking or transparent tape (2 in.)long for each activity group

Testing for Conductors and

Insulators Activity1 D-cell battery (mercury-free, ifpossible) for each activity group

1 strip of aluminum foil, about 1 cm(1/2 in.) wide and 12-15 cm (5-6in.) long for each activity group

Alternative: piece of insulatedcopper wire, 12-15 cm (5-6 in.)long

1 flashlight bulb (about a 3-voltrating) for each activity group

1 clothespin (spring type) foreach activity group

1 piece of masking or transparenttape, about 15 cm (6 in.) long foreach activity group

1 pen or pencil for each student

At least 6 objects to test for eachactivity group (at least three

metal conductors and threenonmetal insulators)

1 copy of Conductors andInsulators Data Sheet for eachstudent (p19)

Make a Battery Holder1 D Cell battery for each activitygroup

1 Toilet paper tube for eachactivity group

2 nails for each activity group

Tape

2 Thick rubber bands for eachactivity group

2 Pieces of foil for each activity

group

2 1-foot long wires with washersfor each activity group

Long strips of newspaper


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PREPARATION ACTIVITIES

Electricity Role Play -- Demonstrate the behavior of an electrical current whenit comes in contact with conductors and insulators.

1. Have the students stand in a continuous line side-by-side.

2. Students will simulate a conductor by putting their arms around eachothers shoulders. The first person in line starts a wave by bending overand then standing back up. This sequentially pulls everyone else in theline over too, simulating electricity flowing through a conductor.

3. Students will simulate an insulator by standing very close together andvery straight, still side-by-side, but this time with their arms down by theirsides. Again, the first person in the line bends over at the waist and

stands up.

What happens this time? Nothing. The first persons bending over has noeffect on the other people in the line. This simulates the effect ofinsulators, which are materials that do not allow electricity to easily flowthrough the material.

4. Point out that a good conductor is a poor insulator and a poor conductoris a good insulator. Brainstorm two lists with the students of objects thatthey think would be good conductors and those that would be goodinsulators. Ask them how they would find out which was which. After

completing the lesson, revisit this hypothesis with the students to see iftheir experiments with insulators and conductors confirm or refute theirpredictions.

Lamp Demonstration-- As a demonstration, take apart an old lamp so thestudents can see its circuits. Remind them NOT to do this at home!

1. Unplug the lamp and remove the shade and bulb.

2. Point out the thin wire filament inside the bulb, and tell students that

electric current flowing through it emits light.

3. Hold up the socket so the students can look inside. Tell them that it hastwo metal pieces or tabs where the electricity flows from the socket intothe metal base of the bulb, and then into the bulbs filament so it can


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produce light. Electricity travels along these metal parts easily becausethey are good conductors.

4. Unscrew the base of the lamp to reveal the cord that connects from thebottom of the lamp pedestal to the base of the bulb socket. Point out the

wires that connect to the base of the socket. The electricity enters andcomes out of the socket and bulb through these connections. Remind thestudents that the path must make a loop or complete circuit back to thesource of electricity.

5. Ask the students to describe and/or draw the path of the electricity fromthe plug to the bulb filament and back to the plug. Tell them that this iscalled a complete, orclosed circuit

Flashlight Circuit Analysis -- Students will take a flashlight apart and trace thecircuits path. Use the drawing on the next page to help students trace themovement of electrons through the flashlights bulb.

1. Unscrew the top or bottom of the flashlight and remove the batteries.Have students look at the batteries and identify the positive and negativeends.

2. Find the metal strip lining the inside wall of the flashlight body where thecurrent from the batteries flows from the battery terminals into theflashlight circuit.

3. Trace the metal strip to the place where it connects to the base of thebulb socket. Find the metal pieces that conduct the current through thesocket to the metal part of the bulb.

4. The current flows through the filament, causing it to glow, then flowsback to the base of the bulb.

5. From the metal base of the bulb, the current travels through the socketto the metal strip or tab that completes the circuit by connecting it to theother end of the battery.

6. Locate the place along this circuit where the switch completes theconnection that allows the current to flow. How does the switch turn thelight on and off?


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PROCEDURAL STEPS

SIMPLE CIRCUIT MAKING ACTIVITY

Distribute one set of materials (battery, foil, bulb) to each activity group. Giveeach student a copy of the Simple Circuit Data Sheet on page 18

Direct the students to look at the battery and compare its two ends.a) Ask them to notice that one is labeled with a negative symbol (-) andthe other end with a positive symbol (+).

b) Which end is dented in slightly? (the negative end)

Which end sticks out? (the positive end)

c) How many volts does it contain? (look at the label- D cells contain 1.5volts)

d) Ask the students which end has the most electrons. (negative terminal)

Direct the students to experiment with the battery, foil strip, and bulb to try to getthe bulb to light. Allow them test their own ideas to find out what works and whatdoes not work, but tell them that each student MUST draw or sketch each circuit

that the group tests on his/her Simple Circuit Data Sheet whether it works or not.

Challenge the students to find as many different ways as possible to build acomplete circuit. If a group is having trouble, ask them to explain or draw acircular path for electrons to follow that includes the bulb and the battery. Helpthem figure out what needs to be connected to make the bulb light.

Hints:a) If the students are having difficulty holding the connections together,suggest that they use tape to hold the foil ends on the battery terminals.

b) To make a good connection between the foil and the metal base of thebulb, the foil strip should be wrapped around the bulb base, leavingenough foil to connect to the battery ends. Using a clothes pin to hold thefoil and bulb, as described in the next activity may help.


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Hold a class discussion using the following questions as a guide:

What did you find most challenging about this activity?Describe how you overcame your challenges.

Answers will vary.

Was there anything that surprised you about any part of the activity?What was it?

Answers will vary.

Compare the circuits that caused the bulb to light up with the ones thatdidnt. How are they alike? How are they different?

The circuits that make the bulb light will have an unbroken path forthe flow of electrons between the positive and negative ends of thebatteries.

Why do you think the other circuits did not cause the bulb to light up?Because the circuit path was broken somewhere, interrupting theflow of electrons and preventing them from reaching the other endof the battery.

How many ways did you find to light up the bulb?Answers will vary.

What do you think happens when one bulb in a string of Christmas lightsis defective?

Somewhere along the circuit path, there is a break that interruptsthe flow of current. In some types of lights, if a bulb bums out, thebreak in the bulbs filament interrupts the path. Lights wired this wayhave series circuits. Other types of lights are designed with circuitsthat can bypass or go around individual light bulbs so that thecircuit is not broken if a bulb burns out. This type of circuit is calleda parallel circuit.

Where might you find insulators and conductors in the world?Electric appliances and motors, generating plants, computers,electric outlets, etc.

Do you think that air is an insulator or a conductor? Why?An insulator, because it does not allow electrons to flow freely andevenly through it.


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Answers To Questions Frequently Asked By StudentsWhy do batteries die?

After a while, the chemical reactions inside the battery that causeelectrons to move are exhausted OR the battery can no longerkeep the negative and positive charges inside the battery apart.

Without a difference in electrical pressure or potential between thetwo ends of the battery, there can be no voltage.

What does the number of volts on a battery mean?The voltage is the limit of the amount of current that can be

produced by the battery.. Batteries, such as A, AA, C, and D carry1.5 volts, but additional voltage can be obtained by connectingbatteries together. For example, flashlights often require 2 batteriesto power a 3-volt bulb.

Why do batteries come in different sizes?

The different-sized batteries contain different amounts of chemicals.Larger batteries contain more chemicals than smaller ones of thesame type, so they can deliver a current for a longer time.

Share the following information with the students

Why It HappensIn order for the light bulb to light, the bulb must be part of an uninterruptedcircuit or path between the two battery terminals. Since electrons will notflow through the bulbs glass or plastic (glass and plastic are insulators),the metal parts of the bulb must be connected to the circuit so they canconduct electricity.

The light bulb lights because it contains a tiny wire, called a filament.Thisfilament has a very high resistanceor opposition to the flow of electricitythrough it. The resistance in the filament causes heat to build until thefilament gets so hot that it glows.

The current in a circuit depends upon the available voltage available andthe resistance of the materials in the circuit. The larger the voltage and/orthe lower the resistance in a circuit, the greater the current produced inthat circuit.

A short circuit is caused when there is no device (bulb or motor) includedin the circuit to use the electricity that is flowing. This causes a largeramount of current to flow, which causes the conductor (foil or wire) to get


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much warmer than usual. It will also cause the battery to die sooner thanit normally would.

Circuits are designed to include a certain amount of resistance. Thisresistance helps regulate the flow of current and keeps too much current

from flowing through the circuit. A circuit with too little resistance causestoo much heat to be produced; that is why a short circuit in a home orbuilding can cause a fire. A 1.5 volt battery does not have enough voltageto produce a dangerous amount of current.

Series circuits have just one path for electrons to follow. Two light bulbsconnected in series with the same amount of current provided causes bothbulbs to burn more dimly than one bulb burning alone. This is becausethe bulbs must share the current.

Parallel circuits offer electrons more than one pathway in which to travel.This allows two bulbs to burn as brightly as one because the bulbs do nothave to share the current. This also allows one bulb to continue shining ifthe other burns out since there is still a complete circuit.


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TESTING FORCONDUCTORS AND INSULATORS

A simple test that is completed with an easy-to build tester can help students distinguishbetween conductors of electricity and insulators. Have students follow the instructionsbelow to build a tester and then use it to test a variety of materials for conductivity.

Build a Tester1. Distribute foil (or wire), bulb, battery, spring-type clothespin, and tape toeach activity group.

2. Tell students to fold the aluminum foil lengthwise in the direction thatwill give them the longest strip of foil. Wrap one end of the foil striparound the metal base of the light bulb and secure it in place with theclothespin.

3. Have students use a piece of masking or transparent tape to hold thefree end of the foil strip to the bottom or negative end of the battery.

4. Test the circuit to make sure everything is connected correctly bytouching the bulb to the top or positive end of the battery. If the bulb doesnot light, ask leading questions that will help the students find and repairthe break in their circuit.

The most likely places for a break in the circuit are between the bulb andthe foil, or between the base of the battery and the foil strip. Often re-wrapping the foil around the base of the bulb and re-clamping the

clothespin or using a new piece of tape to hold the foil to the base of thebattery may fix the connection. If the bulb still does not light, check tomake sure the bulb is working and the battery is charged.

Testing Materials for Conductivity

1. Distribute the test materials to each activity group. Give each student acopy of the Conductors and Insulators Data Sheet, page 19. Ask studentshow they will know if an object is a conductor or an insulator.

If an object is a conductor, the bulb will light when the object is placedbetween the bulb and the battery. If the object is an insulator, the bulb willnot light when that object is put between the bulb and the battery.

2. Before any of the materials are tested, each group should predict whichones will be conductors and which will be insulators and write the


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predictions in the spaces provided on the Conductors and Insulators DataSheet.

3. Groups should test their predictions by placing the objects, one at atime, between the positive end of the battery and the base of the flashlight

bulb wrapped in foil. If the test object is a conductor, the circuit will becompleted and the bulb will light; if it is an insulator, the bulb will not light.

Discuss the class conductor and insulator test results using the followingquestions as a guide:

What was the most enjoyable part of this activity? Why did you think so?Answers will vary.

Were you surprised by any of the results of the test you did? What

surprised you and why?Answers will vary.

Before you tested the objects, how did you decide if the object was aconductor or an insulator?

These answers will vary, but should have something to do with thetype of material from which an object is made.

What objects conducted electricity?Here are some conductors that might have been tested:(If the metal bottle cap has a plastic or other coating, it may behavelike an insulator)

copper wire screw graphite part of the pencil (lead)metal paper clip metal bottle capmetal band on pencilnail coins metal spoonbolt tin can

Which objects did not conduct electricity?Here are some insulators that may have been tested:

string tape plastic spoonplastic cup wood crayon or waxfoam cup pencil eraser plastic bottle caprubber band cloth marble or glass


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How could you tell for sure if an object conducted electricity?The bulb lights!

Compare the objects that conducted electricity. What do they have incommon?

Most of the conductors contain metal.

Why is it dangerous to be wet or standing in water when youre workingwith something electrical?

Unless water is extremely pure, it is a conductor of electricity. Ahuman being who is touching any electrical appliance while wet is aconductor, and will receive a shock when he/she completes thecircuit between the appliance and the water.

Does this mean that water is a conductor or an insulator?Water that contains dissolved materials is a conductor. Only very

pure water is a poor conductor and a weak insulator.

How can you use the information learned in this lesson to be safe aroundelectricity?

Answers will vary and may include safety with electricity and wateror use of insulators in electrical cords.

What should you do if someone receives an electrical shock?Do not touch the person being shocked or you will become part ofthe circuit and get shocked, too. Immediately disconnect thesource of electricity, stay with the person who has been shocked,and send for help.

Share the Following InformationWith Students

Why It Happens

All materials contain atomsand all atoms have electrons.Whether a material allowselectricity to pass through iteasily, though, depends onthe structure of the atom andthe ease with which it allowsits electrons to be moved.


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The best conductors are usually metals because their electrons move easily.Non-metals tend to hold on to their electrons more tightly, which makes thempoor conductors. Those atoms which hold their atoms most tightly make the bestinsulators.

The following list shows some common conductors and insulators. They arearranged in order, with the most efficient conductors and insulators at the top ofeach list. Compare this list to the results obtained in this activity.

Good Conductors Good Insulators

silver amber

copper hard rubber

gold nylon

aluminum porcelain

brass wax , crayons, candles

iron glass

lead wood shellac

mercury very pure water

graphite air

water containing dissolved materials


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INQUIRY AND FOLLOW UP ACTIVITIES

Use the Electron Current Flow activity on page 21 to explore the effect thatresistance has on the flow of electric current.

Explore the concept of using several batteries to increase voltage. Use thedirections on page 23 to construct a battery from a potato or lemon. Explain why thiskind of battery works and how using a series of batteries increases the amount ofelectric current generated. How might this be important in our daily life?

Build a Battery Holder that allows batteries to be connected to circuits easily.

Procedure1. Wrap a stack ofnewspaper strips around thebattery until it fits snugly inthe toilet paper tube. Youmay need some tape to holdthe paper in place. BECERTAIN THAT THEPAPER DOES NOT GOPAST THE ENDS OF THEBATTERY.

2. Put the wrapped battery

into the center of the tube.

3. Mark the tube clearly with+ and -signs to match those on the battery.

4. Gently crumple a piece of foil and put it in the tube on top of the battery.

5. CAREFULLY push a nail through the tube as close as possible to the foil.Use a pencil point if necessary to make holes.

6. Turn the tube upside down and repeat steps 4 and 5. Both nails shouldstick out of the sides of the tube in the same direction.

7. Put a rubber band over the 2 nails on each side. These rubber bandsshould be tight enough to pull the nails toward each other.

8. Attach one wire to each nail by wrapping the bare wire end tightly aroundthe nail.


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OTHER RESOURCES

The Rural Electric Service has an adventure and game page for students, hosted byRus the Surfin Squirrel. It includes information about electric distribution systems,word search games and historical information and pictures of the spread of electricitythrough the U.S. It can be accessed at:

http://www.usda.gov/rus/educate/games.htm

The Miami Museum of Science has a kid-friendly website full of interactive electrical andenergy learning activities. Learn about energy conservation at The Mummys Tomb,play an electric safety game at Frankensteins Electric Library, experience energytransfer with The Wolf Man, and learn the principles of atoms and matter at ThePhantoms Portrait Parlor. Their website may be accessed at :

http://www.miamisci.org/af/sln/index.html

LESSON SOURCE

Lesson Resources:

Funtivities Hands on Science and MathProgram for Women in Science and Engineering210 Lab of Mechanics

Ames, Iowa 50011

Batteries and BulbsJeff Goodman

Appalachian State University Teacher Education Programhttp://www.ced.appstate.edu/~goodmanj/4401/peerteach/lessonplan.htmDownloaded April 17, 2003

Light Up Your LifePatsy TroutUpstate Regional Technology Center Curriculum Technology Integrationhttp://www.myscschools.com/offices/technology/rtc/sptg/esteem/itv/4ec1.htmDownloaded April 17, 2003


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Series CircuitParallel CircuitBuild A Battery Holdercopyright 1997, D.M.CandeloraHands On Technology Programhttp://www.galaxy.net/~k12/electric/Downloaded April 17, 2003

Lesson Written By:

Beth Drescher, County Extension AgentSedgwick County Office of K-State Research and Extension7001 W. 21stSt. N.Wichita, KS 67205

Lesson Reviewed By:

Sharon Hiebert, School 4-H Program CoordinatorSedgwick County Office, K-State Research and Extension7001 W. 21stSt. N.Wichita, KS 67205


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SIMPLE CIRCUIT DATA SHEET

If you construct more than 4 circuits, draw the others on the back of this sheet.

Circuit #1 Did it work? ____ Yes ____ No





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CONDUCTORS AND INSULATORS DATA SHEET

Write your conductor and insulator predictions in the spaces below

Predicted Insulators Predicted Conductors

Test the objects that were given to you and write the actual conductors and insulators inthe correct columns below. Check them against your predictions. How many did youget right?

Actual Insulators Actual Conductors

Which conductors and insulators did you predict correctly? Make a list below.


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SIMPLE ELECTRIC CIRCUITS VOCABULARY

atom building blocks of matter

circuit a continuous path of conductor so that electricity can flow from one end ofthe battery, through the device (light bulb) and to the other end of thebattery

closed a circuit with a complete path that allows electricity to flow freely throughcircuit

conductor a material through which electricity(electric current) can flow easily

electric a form of energy generated by flowing electrons

electricity controlled flow of electrons through a circuit

electron a part of an atom that has a negative charge

Insulator a material through which electricity (electric current) does not flow easily

open an incomplete circuit that will not allow electricity to pass throughcircuit completely

parallel a circuit with several paths for electrons to follow

resistance the measure of the each with which electrons may pass through a material

short circuit a circuit that by-passes the device (light bulb). In this circuit the electricitycan flow from one end of the battery to the other without going through thedevice.

series a circuit that has only one path for electrons to follow

switch turns the flow of electrons off and on


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ELECTRON CURRENT FLOWhttp://www.iit.edu/~smile/ph9118.html

Greg Zipprich

Objectives:

The student will understand how and why electric current passes through a conductordue to a potential difference.

The student will discover the proportional relationship between voltage and resistanceand their effect on the measurement of current flow.

The student will discover that, with a constant voltage, the smaller the diameter of aconductor, the smaller the current flow.

Materials needed:

Five-gallon bucket with globe valve attached to the bottom outside rim

3/4 x 18 CPVC pipe w/screw adapter

1/2 x 18 CPVC pipe w/3/4 screw adapter

1/4 x 18 potable water line epoxied to a 3/4 screw adapter

U-tube constructed from 2 12-oz plastic pop bottles glued into 2 3/4 CPVC 90 oells

connected with an 18" length of 3/4 CPVC pipe

10-foot ladder

Enough 3/4 CPVC pipe and couplings to attach the bucket suspended on the ladder to

pipe lengths on the tabletop

Top watch and a 3-liter pop bottle (graduated).

Strategy:

Working on the principle that water and electricity flow with similar characteristics, a

discussion of electric current flow is conducted making analogies to the flow of water. Inthe U-tube, using water dyed blue with food coloring, the fact is explained that waterdoes not move unless additional water is poured into one side causing a difference inpotential. This causes movement in the water until potential equilibrium is reached.


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Explaining that an excess of electrons at one end of a conductor causes an electricalpotential difference, electrons will similarly flow until electrical equilibrium is reached.How much flows (introduce the term, current) depends on the potential difference orpressure (introduce the term, voltage) and the opposition to flow (introduce the term,resistance).

Using the bucket of water at tabletop height with the three different sizes of pipeconnected to 3/4 screw adapters, measure the volume of water which flows througheach pipe in ten seconds using the graduated 3-liter pop bottle. One student uses thestop watch, another measures the volume and a third keeps a chart of the results on thechalk board.

It can be seen now that if voltage is constant, a smaller pipe (conductor), carries asmaller current. Now the formula, E = I x R, is placed on the chalk board. The studentsdiscuss the relationships of the values and are asked to derive the equation, I = E / R.We have seen that if resistance is high (the smaller conductor), current is low and that,

conversely, small resistance (the larger conductor), transports a larger current. At thistime the quantities are introduced for measuring volts, ohms and amperes.

The students are asked, "Looking at the formula how else can we increase the currentbesides decreasing the resistance?" A student will answer, "By increasing the voltage."

At this time the bucket can be placed on the shelf of the 10-foot ladder. The extra 3/4CPVC pipe and connectors are used to extend the water supply to the tabletop wherethe pipes were before. Again, three students, a timer, a measurer and a recorder, chartthe volume of water from each pipe in tenseconds. More water will come out across thechart because the pressure of the water isincreased. Its potential difference is increased.The students, therefore, find that increasing thevoltage also increases the current.

If time permits, actual values for voltage andresistance can be supplied and the value forcurrent can be calculated mathematically or thiscan be begun on the following class meeting.


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ORGANIC BATTERIESKeith DeWeese

Overview:

Students will make batteries out of lemons, potatoes, and themselves, and hook themup in a variety of ways.

Purpose: (Objective)Students will discover how a battery works, as well as learn how current and voltagerelate and interact.

Materials:

PotatoesLemonsGalvanized (molten, not electrogalvanized) nails3 Copper wire sections2 wires with alligator clips on the endsSandpaperMultimeter

Getting Ready: (Background Information)Explain how voltage and current relate using the equation V=IR. You can go into great

detail about the units used as well (ohms, amperes, volts). Explain how series voltagesadd together while parallel ones dont. Now explain how parallel currents can addtogether.

Motivate! (Engage)Tell the students they are going to make batteries out of lemons orpotatoes. This should be enough.

Activity: (Explore)

First, sandpaper the copper wires. This isnt always necessary, but junk can build up onthem. Next stick the nail and the wire into the potato or lemon. Dont allow them to touchon the inside. Next take the wires with alligator clips and connect one to the nail andone to the copper wire. Measure the voltage with the voltmeter. Measure the current.


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Now take the whole class batteries and hook them up in series and parallel and provethat series voltages add together while parallel currents increase one another.Repeat the entire activity letting each student hold the wire in one hand and the nail inthe other.

Safety Tips:The wires and nails can be sharp. Also, lemon juice in the eye hurts! Dontworry-- nobody can get shocked in this experiment.Concept Discovery: (Explanation) Show the kids that if a whole class links togetherthey can generate 15-20 volts. Give examples of what kinds of voltages are used (12 fora car, 120 for house, 1.5 for a battery). Use their fear of getting shocked to explaincurrent and why you have to have current to get shocked.

Going Further: (Elaboration)

Talk about large quantities of electricity transformers and other things. Put the electricitythey are making into perspective.

Closure:Review the concepts again next week. See if they remember current andvoltage, and the differences between parallel and series circuits.

Assessment: (Evaluation)There is no real way to evaluate anyone on this.

Connections: (Integration with Other Content Areas)This was a good activity to explain prefixes, such as milli. Relating the electronics to

meters and grams made this useful.


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CURRICULAR CORRELATIONSKansas Science Curricular Standards

Standard 1: Science as Inquiry (3rdto 4thgrade)Benchmark 1: All students will develop the skills to do full inquiry. Full inquiryinvolves asking a simple question, completing an investigation, answering thequestion, and sharing the results with others.

*Indicator 1:Ask questions they can answer by investigating*Indicator 2: Plan and conduct a simple investigation*Indicator 3: Employ appropriate equipment and tools to gather data.*Indicator 4:Begin developing the abilities to communicate, critique,analyze their own investigations, and interpret the work of other students.

Standard 1: Science as Inquiry (5thto 8thgrade)Benchmark 1: The students will demonstrate abilities necessary to do theprocesses of scientific inquiry.

*Indicator 1: Identify questions that can be answered through scientificinvestigations*Indicator 2: Design and conduct a scientific investigation*Indicator 3: Use appropriate tools, mathematics, technology andtechniques to gather analyze and interpret data*Indicator 4:Think critically to identify the relationship between evidenceand logical conclusions

Standard 2:Physical Science (3rd to 4thgrade)Benchmark 4: All students will experiment with electricity and magnetism

* Indicator 3: Construct a simple circuit

Standard 2:Physical Science (5thto 8thgrade)Benchmark 4: The students will understand and demonstrate the transfer ofenergy

Indicator 1: Understand that energy can be transferred from one form toanother, including mechanical, heat, light, electrical, chemical and nuclear.

Indicator 2:Sequence the transmission of energy through various real lifesystems.

* = assessed indicator

electric circuits lesson plan

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