Download Electricity

Electricity
Before you unleash the scientist in your classroom, they
need to learn about the basic principles of electricity .
1
Understanding Electricity and Magnets
When we think of magnets and electricity it might seem like they cause things to happen by magic. The reason why magnetism and electricity
seem to be so mysterious is that their forces are invisible to us. Have you ever seen the wind? Think about it. We see the effect the wind has on
objects around us everyday, but we know it's not magic. We know it is windy because we see the trees moving or see leaves in the air. We have
also learned to measure the wind and use it for pleasure and industry. Similarly, we have learned some things about the effects that magnets and
electricity have on objects around us. Even though we can't see it, we know it is there. Let's take some time to try to figure out what makes the
magic displayed by both electricity and magnets.
Electric fields and magnetic fields have similarities, but operate very differently. James Clerk Maxwell was a pioneer in the field of electromagnetism. Maxwell theorized that electricity, light, and magnetism were all related phenomenon. He demonstrated that electric and magnetic fields
travel in a wave and at a constant speed. In this series of worksheets we show you the difference between magnetic and electric fields.
Scientists work to understand natural phenomena and make predictions based on their studies. The ranking order of the most important scientist
of all time is an often talked about topic. One name always comes to the surface as the most influential scientist of all time. The name is Isaac
Newton. As one scholar wrote, "Newton's work was and is the basis for all other scientists."
To know how magnets and electricity work we need to realize that everything around us is made up of atoms full of electrons, protons and neutrons. It is in the make up of atoms that the world of electricity and magnetism exist. Each atom has a center called a nucleus filled with particles
called protons and neutrons. The atom also has particles called electrons that orbit around the nucleus. Electrons and protons have what we refer
to as a charge. Protons in the nucleus have a positive charge. The electrons orbiting the nucleus have a negative charge. Neutrons, on the other
hand, have a neutral or no charge. Neutrons add to the mass of the atom and are thought to help hold the nucleus together.
In both electricity and magnetism it is the positive and negative charges at work that cause things to happen. In magnets there are two parts,
positive and negative. For example, one end of a magnet will be positively
charged and the other end negative. When you place two magnets together,
the similar charged ends will repel or push away from each other. The oppositely charged ends will attract and cling to each other.
The Earth itself is also like a large magnet with magnetic fields coming from
its north and south poles, radiating into space. We can use magnetism to see
the direction of the Earth's magnetic fields with a compass that always wants
to point to the magnetic north pole. This may seem like magic but what is
actually happening is that the positively charged particles are attracted to
negatively charged particles. In electricity, something similar is also happening. The positive protons are attracted to the negative electrons.
Electricity and magnets are similar in that they both work because of the effect of positive and negative forces acting on each other. Because the positive
proton is trapped in the nucleus of the atom, it is the moving negative electrons that are mostly responsible for the working of electricity.
We can see the effects of moving electrons in electricity even in our own bodies when we shuffle our feet on a rug then touch another person or object
causing a small arc or spark of static electricity. If you do the same thing in
the dark and watch very closely you can even see the spark between your finger and the other object. The spark is caused by the build up of electrons
jumping to the other object. The atom always wants to equalize the number of
protons and electrons so some jump to adjust the balance between the two
objects.
The next time you see lightning, remember it is really a big spark of electricity caused by 2moving electrons jumping from one place to another and causing a beautiful light display.
Understanding Electricity and Magnets
Magnetism & Electricity Vocabulary List & Definitions
Vocabulary
Word
Definition
current
is the flow of electricity in a conductor.
electricity
is a physical phenomenon caused by the movement of certain charged particles such as electrons, esp. between points having
different electrical charges, and seen in naturally occurring phenomena such as lightning and magnetic attraction and
repulsion.
electromagnet
is a magnet in which an iron or steel core is magnetized by the electric current in the coil of insulated wire wound around it.
electron
is a negatively charged particle, considered a fundamental unit of matter, that exists independently or outside the nucleus of an
atom.
force
is active power, energy, or physical strength.
lodestone
is a rock that possesses magnetic properties and attracts iron; magnetite.
magnet
is an object that attracts iron and some other materials by virtue of a natural or induced force field surrounding it.
attract
is to cause to come near, as by some special quality or action.
battery
is a device that generates electricity by means of chemical reactions.
repel
is to drive away or force backwards.
circuit
is an Arrangement of electronic elements, including conductors, resistors, and the like, through which electric current moves.
compass
is an instrument for determining direction, esp. one with a horizontal magnetic needle that rotates freely until it points to the
magnetic north.
http://science.lotsoflessons.com/electricity.html is a link that will provide PowerPoint presentation for use with your students.
3
Understanding Electricity
What's Electricity?
Directions:
Answer the questions found below.
1. Electricity is the flow of ______________________________.
2. Electrons have a __________________ charge.
3. Protons have a ___________________ charge.
4. Neutrons have a _________________ charge.
5. The electric force that pushes electrons is measured in ________.
6. Is using a telephone during a lightning storm is dangerous?
Bonus:
How come birds on electric wires don't get electrocuted?
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Understanding Electricity
Magnetism Worksheet
Fill in Words
stars)
The
physician
and
stroked
Chinese
power
the
stones
from
Europe
away
A
around
the
____________ ancient Greeks, originally those near ____________ city of Magnesia, and also the
early Chinese knew about strange and rare ____________ (possibly chunks of iron ore struck by lightning) with the ____________ to attract iron. ____________ steel needle ____________ with such a
"lodestone" became "magnetic" as well, ____________ around 1000 the ____________ found that
such a needle, when freely suspended, pointed north-south. The magnetic compass soon spread to
____________ Columbus used it when he crossed the Atlantic ocean, noting not only that the needle
deviated slightly from exact north (as indicated by ____________ ____________ but also that the deviation changed during the voyage. Around 1600 William Gilbert, ____________ to Queen Elizabeth I
of England, proposed an explanation: the Earth itself was a giant magnet, with its magnetic poles some
distance ____________ ____________ its geographic ones (i.e. near the points defining the axis
____________ which the Earth turns).
5
Understanding Electricity
Do The Research on Magnetism and Electricity
Directions: Research the topic indicated and answer the questions below, based on that topic.
1.
What happens to a magnet if you heat it too much?
2. Has the magnetic field of the Earth ever flipped (i.e. North Pole would be South)?
3. When is the only time that light waves travel at the speed of light (186,272 miles per second)?
Magnetism and Electricity Group Creative Writing
Directions: As a group, you have 25 minutes to write a brief story using the words below.
ATTRACT
BATTERY
CIRCUIT
REPEL
ELECTROMAGNET
LODESTONE
CURRENT
COMPASS
MAGNET
FORCE
ELECTRONS
6
ELECTRICITY
Understanding Ohms & Volts
These basic principles of electricity are the basis for the electric devices found in your home and school — things like digital cameras, stereos, flashlights, calculators and portable CD players.
Ohms and Volts
Scientists know that there are ways of measuring electrical quantities. One of these is coulombs per second, a measure of the flow
of electrons through a metal conductor or wire. A current of one coulomb per second equals one ampere.
Even materials that conduct electricity resist the flow of electrons. The unit of electrical resistance is an ohm. The pressure needed
to make one coulomb per second (one ampere) flow through a conductor having a resistance of one ohm is one volt.
Ohm's Law explains the relationships between voltage (E), resistance (R), and current (I).
In two circuits of equal voltage, the current will be proportionately greater in the circuit of lower resistance. In circuits of equal
resistance, the current flowing will be directly proportional to the voltage applied. Current is directly proportional to voltage, inversely proportional to resistance.
I (Amperes) = E (Volts)/R (Ohms)
Also: E = IR or R = E/I
One of the most common electrical measurements you’ll use is the watt, a unit of electrical power: W (Watts) = E (Volts) x I
(Amperes).
The quantity of electric charge is measured in coulombs.
Scientists and engineers use their knowledge of electricity to design the latest instruments, tools and devices. And you can put the
principles of electricity you’ve just learned to work with the science of
batteries.
Please Read Carefully!
All experiments use safe, low-voltage battery power. Household electrical current contains high voltage that could cause serious
injury. DO NOT use household electrical current for any of these experiments. ALL experiments should be conducted under adult
supervision.
Carefully follow wiring instructions for each experiment. Improper wiring can result in battery
leakage and/or rupture.
DO NOT take a battery apart. Contact with internal battery material can cause injury.
DO NOT dispose in fire, recharge, put in backwards, or mix with used or other battery types.
This may cause batteries to explode, leak and cause personal injury.
Credits:
Energizer
7
How to Build a Power Pack
Please Read Carefully!
All experiments use safe, low-voltage battery power. Household electrical current
contains high voltage that could cause serious injury. DO NOT use household electrical current for any of these experiments. ALL experiments should be conducted under adult supervision.
Carefully follow wiring instructions for each experiment. Improper wiring can result
in battery leakage and/or rupture.
Materials:
·
2 Energizer® MAX ® D batteries,
out of the package
·
Electrical tape
·
Insulated number 22 copper wire
·
Two metal paper clips
DO NOT take a battery apart. Contact with internal battery material can cause injury.
DO NOT dispose in fire, recharge, put in backwards, or mix with used or other battery types. This may cause batteries to explode, leak and cause personal injury.
Steps to Building an Energizer® Power Pack:
Place the two batteries side by side with the positive terminal right-side up on one
battery and the negative terminal right-side up on the other. Use electrical tape
around the middle of the batteries to secure them together.
Standing the batteries upright, place a paper clip between the positive and negative
contacts. Use a four-inch piece of electrical tape to secure the paper clip in place.
Cut two pieces of wire about 14 inches long. Strip approximately one-half inch of
insulation from one end of the wires. Turn the battery pack over, exposing the two
unused battery contacts. Place the stripped portion of one of the wires on a battery
contact and secure it in place with a three-inch piece of electrical tape. Repeat this
procedure with the other battery and wire. Strip the insulation on the other end of the
wires back about one inch. They are now ready to provide power to your experiments. It is important that the bare wires do not touch each other and cause a short
circuit. We recommend that you temporarily cover the end of these bare wires with
electrical tape to avoid accidental shorting of the batteries.
Now that you've built your Energizer® Power Pack, you're ready to begin exploring
the science of batteries brought to you by Energizer!
Credits:
Energizer
8
Make a Simple Circuit
For this project, you'll build a switch that allows you to control the flow of electricity. This switch can then be
used in the other experiments.
Materials:
All experiments use safe, low-voltage battery power. Household electrical current contains high voltage that could
cause serious injury. DO NOT use household electrical current for any of these experiments. ALL experiments
should be conducted under adult supervision.
Carefully follow wiring instructions for each experiment - improper wiring can result in battery leakage and/or
rupture.
DO NOT take a battery apart - contact with internal battery material can cause injury.
DO NOT dispose in fire, recharge, put in backwards, mix with used or other battery types - may explode, leak and
cause personal injury.
·
Energizer® Power Pack
·
Spring-tension wood or plastic
clothespin
·
Number 22 insulated copper bell
wire (three 10" pieces with 1" of
insulation stripped off both ends of
all wires)
·
Small blocks of wood
·
One drywall nail, thumbtacks, paper clip
·
·
3-volt flashlight bulb
How to Build a Switch:
Wind a bare wire end around a thumbtack. Hook a paperclip around the tack and press it into a wood block.
Wind the second bare wire end around another thumbtack and press it into the wood.
This wire will connect to your Energizer® Power Pack positive (+) lead wire.
Place a third thumbtack in the middle of the wood block to hold your paper clip switch in place. Your switch is
now completed.
Please Read Carefully!
Alternate: Insulated knife blade switches are available commercially, and are used to illustrate the experiments
throughout this site.
How to Build a Bulb Holder:
Nail a clothespin to a wood block.
Place a loose wire from switch (step #1) with a tack into the wood directly under the clothespin jaws.
Wrap one stripped end of the remaining unconnected wire around the bulb. Clamp it in the jaws of the clothespin
with thumbtack below in order to make a complete circuit.
Tack the loose wire to the wood. This wire will connect to your Energizer® Power Pack negative (-) lead wire.
Alternate: Insulated light bulb holders are available commercially, and are used to illustrate the experiments
throughout this site.
How to Complete the Simple Circuit:
Take wire from "How to Build a Switch" step 3 and bend stripped end at right angle. Connect wire to positive (+)
lead of your Energizer® Power Pack with tape.
Take wire from "How to Build a Bulb Holder" step 3 and bend stripped end at right angle. Connect write to negative (-) lead of your Energizer® Power Pack with tape.
When the circuit switch is open, the current does not flow to the bulb. With your finger, press down on the paper
clip switch. You are closing and completing the circuit so the electricity can flow to the bulb.
Credits:
The switch, bulb holder, and portable power are a complete circuit and arrangement of conductors; they
allow the passage of electric current through the wire. Metal objects make the best conductors. Copper, brass,
steel, or a strip of tin can have many free electrons capable of being moved along by an electromotive force such
as voltage from9the battery. In insulators, such as the wire covering, electrons do not move easily, so you can
work with electricity safely.
Energizer
Electricity
Making Conductive Dough
Procedure:
Materials:
1. Mix water, 1cup of flour, salt, cream of tartar, vegetable oil, and food coloring in a medium sized
pot.
2. Cook over medium heat and stir continuously.
3. The mixture will begin to boil and start to get chunky.
1 cup Water
1 1/2 cups Flour
(A gluten free version of this dough
can be made by replacing the flour
with gluten-free flour.)
1/4 cup Salt
3 Tbsp. Cream of Tartar*
1 Tbsp. Vegetable Oil
Food Coloring (optional)
*9Tbsp. of Lemon Juice may be
Substituted
4. Keep stirring the mixture until it forms a ball in the center of the pot.
5. Once a ball forms, place the ball on a lightly floured surface.
WARNING: The ball will be very hot. We suggest flattening it out and letting it cool for a couple
minutes before handling.
6. Slowly knead the remaining flour into the ball until you’ve reached a desired consistency.
7. Store in an airtight container or plastic bag. While in the bag, water from the dough will create condensation. This is normal. Just knead the dough after removing it from the bag, and it will be as good
as new. If stored properly, the dough should keep for several weeks.
Credits:
University of St. Thomas
10
Electricity
Making Insulating Dough
Procedure:
1.
Materials:
Mix solid ingredients and oil in a pot or large bowl, setting aside ½ cup flour to be used later.
1 1/2 cup Flour
1/2 cup Sugar
3 Tbsp. Vegetable Oil
1/2 cup Deionized (or Distilled)
Water
(Regular tap water can be used,
but the resistance of the dough
will be lower.)
2. Mix with this mixture a small amount of deionized water (about 1 Tbsp.) and stir.
3. Repeat this step until a majority water is absorbed by the mixture.
4. Once your mixture is at this consistency, knead the mixture into one “lump”.
5. Knead more water into the dough until it has a sticky, dough-like texture.
6. Now, knead in flour to the dough, until a desired texture is reached.
7. Store in an airtight container or plastic bag. While in the bag, water from the dough will
create condensation. This is normal. Just knead the dough after removing it from the bag, and
it will be as good as new. If stored properly, the dough should keep for several weeks.
Credits:
University of St. Thomas
11
Electricity
Materials:
·
RadioShack® Enclosed 4 “AA” Battery Holder Model
270-409
·
Insulating Dough
·
Conductive Dough
·
Buzzers should have an operating voltage range that
includes your battery pack voltage. Usually all buzzers
have a low current draw, but less than 30mA works
best. Have a variety of buzzers that we use, most from
RadioShack
·
Motors are components to transform electrical energy into
movement. Many motors will work for Squishy Circuits.
We have found motors work best that have a very low current draw (~30mA) and are rated for about 5 volts.
·
LEDs (Light Emitting Diodes) are great Squishy Circuits components because they need very
little current and voltage to create light! They are different than regular lightbulbs, being much
more efficient, because they do not have a filiment and produce light directly. LEDs come in
many different shapes, sizes, and colors, but we really like to use a 10mm diffused lens
LED because they are large and easy to see.
·
Also note that the salt in the
conductive dough rusts components over time. Wiping the
components after use with a
damp towel may promote
their longevity.
·
Most of our devices work best
with terminals, for instructions on how to do this . Directions on the following
page.
·
We encourage you to try your
own variations to the activities! Share pictures of your
creations with the Squishy
Circuits Facebook Community
·
These activities are designed
such that the dough is used to
connect components. Never
connect components, such as
LEDs, directly to the battery
pack, as running too much
current through components
can damage them, possibly
causing them to overheat or
pop. Follow standard electricity safety considerations. (Our
youngest participants are fans
of these brightly colored
safety glasses!)
Credits:
University of St. Thomas
12
Now you are ready to try the experiments on the next few pages
Electricity
Adding Terminals
We have found that adding terminals to the wire leads of the 4AA battery pack, which increases the surface
area, works the best. To do this you will need a battery pack, wire stripper/terminal crimper, and 2 fork (or
spade) terminals.
A properly crimped connection, which physically secures
the wire and makes an electrical connection.
Optional, but highly recommended: Solder the terminals to improve physical and electrical strength of the connection.
Properly crimped and soldered terminals ready to be used.
We also crimp and solder terminals onto many of our Squishy Circuits components, such
as this motor.
13
Electricity
Building Squishy Circuits
Safety:
These activities are designed such that the dough is used to connect components. Never connect components, such as LEDs, directly to the
battery pack, as running too much current through components can damage them, possibly causing them to overheat or pop. Follow standard
electricity safety considerations. (Our youngest participants are fans of these brightly colored safety glasses!)
Circuit Basics
Electricity flows in a loop called a circuit. A circuit starts and stops at the battery pack, and flows through wires, conductive dough, and
electrical components such as LEDs and motors.
Circuit Basics –Short Circuit
Electricity is like water; it takes the path of least resistance. It is easier for the electricity to flow through the dough than through the LED, so
if the dough on each side is touching, electricity does not flow through the LED at all. Therefore, the light stays unlit. This is called a short
circuit.
Circuit Basics –Insulator vs Conductor
Instead of separating the pieces of dough, you can also use the insulating dough to separate the conductive dough. Unlike conductors,
insulators do not electricity flow through them, so the electricity must go through the LED.
Circuit Basics—LED
The LED (Light Emitting Diode) produces light from electrical power. To work, it has to be oriented properly (this is called polarity). Usually
the two leads are different lengths. The longer lead goes to the positive, or red, side of the battery pack. The shorter goes to the negative, or
black, side of the battery pack.
You must have dough between the LED and battery terminals or else the LED will burn out.
Also note that the salt in the conductive dough rusts components over time. Wiping the
components after use with a damp towel may promote their longevity.
14
Electricity
Series and Parallel Circuits
Series Circuits
·
A series circuit only allows one path for the electricity to flow through.
·
Note that the dough acts as a resistor and a wire, therefore the resistor as show in the schematic are not needed.
·
A LED only works in one direction. Make sure the longer wire or lead is towards the positive (red) side. Also, never directly connect and
LED to a voltage source (battery) because it will burn out.
LEDs can be added however they will get more dim because there is less electricity available to power them. If one of the LEDs is taken out,
the entire circuit is broken and all of the lights will go out.
Parallel Circuits
·
A parallel circuit allows multiple paths for electricity to flow through.
·
Also note that the dough acts as a resistor and a wire, therefore the resistors as show in the schematic are not needed.
·
A LED only works in one direction. Make sure the longer wire or lead is towards the positive (red) side. Also, never directly connect and
LED to a voltage source (battery) because it will burn out.
LEDs or other electrical items are connected to the dough each in their own loop or circuit. Since electricity flows through each LED
independently, if one is removed or burns out, the others will continue to shine brightly.
15
Electricity
Motor Circuit
Motors can be used to bring motion to your Squishy Circuit creations. The motor has two leads, like the LED, but orientation, or polarity, is
not necessary. However, the polarity does change the direction the motor spins.
Buzzer Circuit
Buzzers can be added to your Squishy Circuits by matching the red lead from the buzzer to the red lead of the battery pack and the black lead
from the buzzer to the black lead of the battery pack.
16
Visit http://courseweb.stthomas.edu/apthomas/SquishyCircuits/buildingCircuits.htm
for more information on other activities your students
can do with Squishy Circuit creations.
Electricity
SIMPLE CIRCUIT
Background
Materials
Unlike static electricity that can exist on a single object, electrical current flows between objects.
Procedure
1. Figure out how to make the light bulb light.
2. Once you figure it out, draw a "schematic" of your circuit on the next page. This sort of picture is
used to describe how to build a particular circuit. It uses symbols to represent things like the battery
and light bulb. It shows what each wire connects together. Here are some of the symbols you can use
for your schematic:
·
·
·
·
·
·
1 bread board
2 wires with washers
1 piece of string
1 battery in holder
1 light bulb
push pins
3. Once you have drawn your schematic, see how many different ways you can get the bulb to light.
Draw a schematic for each one. What things are necessary in your circuit for the bulb to light?
4. Build the circuit shown here and make sure the bulb lights. Take out one of the wires. What happens? Why?
5. Build the circuit shown here and make sure the bulb lights. Replace the wire by the string. What
happens?
Question
The string is an insulator and the wire a conductor. How might you define these terms?
An insulator is
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________________________________________________________________________________
________________________________________________________________________________
A conductor is
_______________________________________________________________________________
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Credits:
ProTeacher Community
17
Electricity
PARALLEL CIRCUIT
Background
Materials
Light bulbs are in parallel if they are side-by-side. They still share the electrical energy but they affect
each other differently than if they were in series.
Procedure
·
·
·
·
·
2 batteries in holders
1 breadboard
2 light bulbs
4 wires with washers
push pins
1. Connect up the simple circuit with 2 batteries.
2. Now replace the single light bulb by two in parallel as shown.
3. Remove one bulb from its socket. What happens? Why?
__________________________________________________________________________________
__________________________________________________________________________________
4. How does the operation of this parallel circuit compare to the series circuit you worked with earlier?
__________________________________________________________________________________
__________________________________________________________________________________
Credits:
ProTeacher Community
18
Electricity
SWITCHED CIRCUIT
Background
Materials:
Switches provide an easy way to open and close an electrical circuit.
Procedure
1. Assemble the simple circuit with 2 batteries. Open and close the wires to turn the bulb off and on.
2. Now wire in the paper clip as a switch as shown and use it to turn the light on and off.
Question
·
·
·
·
·
·
2 batteries in holders
1 breadboard
1 paper clip
2 light bulbs
2 wires with washers
push pins
Why does the light go out when you move the switch?
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
Credits:
ProTeacher Community
19
Electricity
SIGNALING
Background
Signaling is a way to communicate where speaking won't work. Smoke signals, football signals and telemetry signals to spaceships are some
examples. Signaling is also used to move information around inside of circuits.
Materials:
1 battery in holder
1 light bulb
push pins 1 toothpick
2 1-foot wires with washer at one end
1 breadboard
2 three foot wires
1 rubber band
1 book Build A Switch
First you have to make a "momentary" switch. Here's how:
1.
Take a wire that has no washer on one end and tightly wrap the bare wire around the end of one craft stick. The wires should be touching
each other. Use the other wire for the other craft stick.
2. Put the 2 sticks on top of each other with the wires touching. Wrap a rubber band tightly around the other end.
3. Put the toothpick between the craft sticks near the rubber band. The wires should now touch when you push down on the switch and open
up when you stop pushing.
4. Now that you have your switch, go on to the next page to finish this experiment. You will need to work with another team.
Procedure
1. Build the simple switched circuit using long wires so that your light can be placed a long way from the battery on the other team's breadboard. Keep your switch close to your battery. . 2. Put a book upright between the two breadboards so that you cannot see the light and switch
the other team.
3. Write a one word question and translate it into Morse Code.
4. Use Morse Code to ask the other team your question. Turn your light on for a "long" time for a dash and a "short" time for a dot. Use an
extra-long flash of light to indicate that you are done.
5. Now decode their answer. Write down the dots and dashes. Then translate them into letters.
20
Electricity
21
Electricity
LIGHTNING ROD
Background
It too much electrical energy flows through objects they can overheat and cause fires. Since electrical current prefers the path of least resistance, we can easily protect our homes from the energy in lightning.
Materials Needed
2 batteries in holders
1 paper clip
tape
1 breadboard
push pins
2 light bulbs
paper
3 wires with washers
pencil
Procedure
1. Cut a lightning bolt out of paper.
2. Build the simple circuit with 2 light bulbs in series. Tape one bulb on the paper lightning bolt. When this light is lit it will indicate that
lightning is striking.
3. Make a house out of paper. Houses tend to be made of wood, bricks, etc. Are these things good conductors?
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4. Put the other light bulb on the house. When this light is lit it will indicate that the house has been damaged by lightning.
5. Simulate lightning striking the house by briefly closing the switch.
6. Now protect the house by building a circuit parallel to the light. This circuit must have resistance that is lower than the house so use just a
plain wire.
7. Make lightning strike again by closing the switch. What happens?
Why?
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22
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Electricity
Brown Bag Science
GRADE LEVEL: Appropriate for grades 1-5
OVERVIEW: This is a hands-on science investigation on electricity. Students learn through the discovery method how electricity works.
The student's natural curiosity and sense of exploration will enable them to explore and learn on their
own with little input from the teacher.
RESOURCES/MATERIALS: All
items can be bought very inexpensively at Radio Shack or from
Edmond Scientific Elementary
Catalogue.
PURPOSE: The purpose of this investigation is to introduce students to the concept of electricity and
dispel any fears they may have that they don't understand the concept. This is excellent for girls, who
Materials:
often feel that they don't or shouldn't understand electricity as well as boys.
·
brown lunch sack,
·
one C cell battery,
·
two insulated copper wires,
·
one battery holder
4. Be able to make an electrical motor work and add a switch to turn it on and off.
·
two brass battery clips,
ACTIVITIES AND PROCEDURES:
·
one small flashlight bulb and
socket.
OBJECTIVES: As a result of this activity, the students will:
1. Be able to draw and explain how an electrical circuit works.
2. Be able to define and use vocabulary associated with electricity. Vocabulary: circuits, electrons,
force, conductors, switch, insulation
3. Be able to construct a simple circuit and a parallel circuit.
1. The teacher will prepare ahead of time a kit for each two or three students. If students work in larger groups, some will not get hands on experience. Each kit will include a brown lunch sack, one C
cell battery, two insulated copper wires, one battery holder and two brass battery clips, one small
flashlight bulb and socket. All these items must be separate and in random order in the bag. The bag
must be closed, sometimes I close it with one of the copper wires like a twisty.
2. Give each pair of students a bag and allow 10 minutes for exploration. During this time the teacher
must remain quiet unless asked a question. The students will be very busy trying to find out
what to do with the contents of the bag. Do not give any clues as to use of contents. This is
exploration time.
3. Before the 10 minutes are up some students will have undoubtedly have made a simple circuit with
the contents of the bag. At this time you can stop for discussion. Have the students explain what they
did so others can follow. You can now talk about the concept of electricity, the flow of electrons
through a conductor , discuss what things are conductors, etc. Discuss where the electricity comes
from and where it goes, how does it make the light bulb light. Discuss how the battery stores
electricity. How do we know that electrons are flowing?
4. After all students have been successful with the simple circuit, each pair must draw what they have
done in their science log or on a piece of paper. Older kids will label all the parts of the circuit, etc.
5. At this time, I give each pair of students a second battery and let them experiment. Does the second
battery change anything? Does the light get brighter or dimmer? Does the way the batteries are connected make any difference in the way the light works. Try different ways of connecting the batteries.
Some students will make a parallel circuit. At this time stop and have the students tell what they did.
Discuss the concept
of parallel circuits. Each pair of students draw what they have done.
23
Continue on next page.
Credits:
Judy Adair, Spring
Creek Elementary,
Electricity
6. A follow up activity if you have time is to have switches available. For those students that finish quickly, they get a switch. See if they can
connect it into the circuit to make the light come on and off. Discuss how electricity flows. Why does the electricity not cross over the switch
when it is open? Does electricity jump? Again, each pair must draw what they have done. This completes the thinking process and makes
the learning more personal.
7. Electrical motors can also be added. Students enjoy making small fans out of the motors. Each pair of students can exchange their light
bulb and socket for a small electric motor and try to connect it into the circuit. Torn or cut paper makes great fan blades. Let the students
experiment to find the best size and shape to make the fan go very fast.
8. The role of the teacher in this activity is to be a facilitator. Please refrain from your urge to teach. In this activity, students discover the
concept of electricity. The less you show and tell the better.
TYING IT ALL TOGETHER:
1. Check each pair of students diagrams and leave small personal messages so they will know that you have looked at what they have done.
2. Encourage all students to share what they have learned with other students and parents.
3. I have done this activity with students in grades 1-5 and all have learned and had great fun doing so. For the younger students their drawings will be less sophisticated and you do not need to dwell on vocabulary. With older students, they will need to label and use the vocabulary
correctly. Most students are so eager to get hands on experience in science and with this activity, all students can experience success.
24
Electricity
Demonstration of Induction
Wind two coils with 28 or 30 gauge magnet wire. A low voltage battery (from a flashlight will do) is connected to one coil. Connect a 9 volt battery to the other coil, except with a switch to break the circuit. Put both coils around a magnetic "core" - a large nail or even a bolt will work. You
will notice that each time you connect and disconnect the battery from the coil, the light bulb will light. But of course, it isn't continuous because
the magnetic field has to be moving, so you have to have a pulsating current. The bulb will flash each time the battery is connected and disconnected. You will get varying results, depending on how many turns you have on the coils, the gauge of the wire, and the distance between the
coils. You will have to play around with it a little to get the bulb to light. This demonstrates electromagnetic induction, and the principles at work
in a transformer. The coils in this little experiment are like the primary and secondary windings in a transformer. You're basically making two
electromagnets on the same core, with only one having power.
You can save a little bit of work, if you have an electronics store nearby. Look for a "solenoid coil," preferably one wound for AC. A solenoid is
basically just an electromagnet. A lot of common items have solenoids...automatic sprinkler valves have solonoid coils to open and close the
valve. For safety, you'll want one for low voltage, maybe 6 or 12 volts AC. If you find a solenoid, you can use that as a primary winding and then
you just need to make a secondary. If you do use an AC solenoid, you will need a transformer to step the outlet line voltage down, but you can
get one very easily and cheaply. A small 6 volt transformer at Radio Shack was about $5 the last time I saw. The kids can even try winding different size secondary coils on the "homemade transformer" and see how it effects the experiment. You can get a cheap analog multimeter ($10 or
even less sometimes) and actually measure how the voltage on the secondary is affected by the size of the coil and number of turns. And of
course, a multimeter will come in very handy for many other experiments.
There are so many things they could learn from this experiment...
1. Induction - two coils not connected. One is supplied with a pulsating current, and electricity is transferred to the other coil, which is shown by
a bulb lighting each time the current is applied and disconnected momentarily.
2. Transformer action - Voltage (and current) can be varied by changing the number of turns on the secondary winding.
3. Frequency - the kids might catch on and understand what alternating current from an outlet (or the "AC mains" as we call it) really is. When
we plug a lamp into an outlet, it is actually flashing just like the bulb was in the experiment, but it's flashing so fast that our eyes don't percieve it,
so the light seems continuous. They may learn a new term, "frequency," meaning how fast an electric current is pulsating (or in the case of AC,
how fast it is changing direction). Common household AC is 60 Hertz, or 60 cycles-per-second.
Electricity can definitely be a very fascinating subject to learn about, and I think 6th graders would be able to understand it. Of course, this experiment is really simplifying things...there are a LOT of other factors that go into a transformer, like things called "impedance," "inductive reactance," "current regulation"...but I definitely won't get into all that here!
:
If you can talk to someone who has a Tesla Coil, then you'd really be in business. You can find out more
about a Tesla Coil online, but they generate very high voltage at radio frequency and can light up florescent
and neon tubes without any wires! I built one a few years ago. A Tesla Coil generates some amazing effects,
but they can be dangerous and have to operated by someone knowledgable.
Try looking on Google for induction, impedance, inductive reactance, current regulation for more
Credits:
experiments.
ProTeacher Community
25
Electricity
STATIC ELECTRICITY
Background
Invisible electrical charge can build up on objects that rub together. Sometimes this happens to clouds.
The discharge can go unnoticed or be spectacular like lightning.
Procedure
1.
Pull two desks apart and put the ruler between them. Tie the string around the middle of one pen
and tape it in place. Use the string to hang this pen from the middle of the ruler. The pen should
not be touching either desk.
Materials
2 plastic stick pens
1 ruler
1 piece of wool
12" of string tape
2. For the rest of this experiment if you are asked to charge a pen, hold it by its cap and rub it briskly
50 times with the piece of wool. If you are asked to discharge a pen, roll it gently between your hands
a few times.
3. Discharge both pens. Hold the loose pen by the cap and slowly bring it near the other pen. Observe
what happens and record this in the chart on the next page.
4. Now charge the loose pen. Hold it by the cap and slowly bring it near the other pen. Observe what
happens and record this in the chart below.
Hair Raising Phenomenon
Materials:
latex balloons (oblong shape is better than round)
5. Discharge the loose pen. Now record what happens when you bring it near the other pen?
6. Charge both pens. Record what happens when you bring them near each other.
7. Discharge the loose pen but leave the hanging pen charged. Record what happens when you bring
them near each other.
Conclusion
If two objects are charged the same, they _____________________ each other. If they are charged
differently, they _____________________ each other.
Static Electricity - A Hair Raising Phenomenon
Grade Level: K - 6
Discussion: For years children at birthday parties have played with static electricity - whether they
realized it or not. Bring this fun exercise to your classroom with the following simple experiment.
Procedure: On a cool, dry day blow up the balloon and rub it on a rug or sweater. Bring the balloon
close to a student's head. What happens? The hair rises to meet the balloon.
By rubbing the balloon, you electrically charged it. The hair rises toward the balloon because of that
charge. (Individuals
can try this with the hair on their forearms. The electrical charge is also strong
26
enough to hold the balloon against the wall for a short time. Try it and see how long the balloon will
stay.
Credits:
ProTeacher Community
Electricity
RESISTANCE
Background
Resistors pass some electrical energy but convert some ot it to heat. They are neither conductors nor
insulators but somewhere in between. Procedure
1. Build a simple parallel circuit. Both light bulbs should be lit equally.
2. Break the circuit to one of the lights and reconnect it with a resistor in the path. The resistance of an
object is measured in Ohms. The higher the resistance, the more Ohms the object has. Resistors typically have the number ot Ohms marked on them. Start by using the 10 Ohm resistor.
Materials:
·
2 batteries in holders
·
1 breadboard
·
4 wires with washers
·
2 light bulbs
·
push pins
·
2 10-Ohm resistors
·
1 100-Ohm resistor
3. With the resistor in the circuit, observe and record what changes have occurred in the two lights.
___________________________________________________________________________________________
___________________________________________________________________________________________
4. Replace the resistor by the 100 Ohm resistor. What happens?
___________________________________________________________________________________________
___________________________________________________________________________________________
5. What do you think would happen if you put a 10 Ohm resistor in BOTH paths?
___________________________________________________________________________________________
__________________________________________________________________________________________
Try it. What happens?_________________________________________________________________________
Question
You have now learned about 3 types of electrical materials. What are they?
1. _________________________
Credits:
2. _________________________
ProTeacher Community
3. _________________________
27
Electricity
MAGNETS
Procedure
Investigate your magnet. Try different things and write down five observations that you make.
1.______________________________________________________________________
2.______________________________________________________________________
3.______________________________________________________________________
Materials:
·
·
·
·
·
2 bar magnets
1 compass
2 bar magnets
assorted magnets
2 round pens or pencils
4.______________________________________________________________________
5.______________________________________________________________________
MAGNETIC POLES
Background
For electricity we found that there were positive and negative charges, that like charges repel each
other and opposites attract. Let's see if there's an analogy for magnetism.
Materials Needed
1 compass
2 bar magnets
assorted magnets
2 round pens or pencils
Procedure
1. The bar magnets are marked with North and South poles. Put the pens under one of the bar magnets
for rollers. Use the other bar magnet to determine if like poles attract or repel. Record your findings.
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
2. Move all of the magnets away from one bar magnet. Put the compass at the end of the magnet
marked "N". Draw an arrow on the diagram below showing what direction the painted end of the compass needle points. Then repeat for the end marked "S".
Credits:
3. Use the compass in the same way to determine the location of the North and South poles for each of
the other magnets. Draw a sketch of each one and show the poles.
28
ProTeacher Community
Electricity
MAGNETIC FIELDS
Background
A magnetic field is the area around a magnet where its magnetic force can be felt.
·
·
Procedure
1.
Materials:
1 bar magnet
1 compass
Place the magnet in the center of the next page.
2. Put the compass near one end of the magnet. Let the needle stop moving. Note the direction of the
needle. Lift the compass and draw an arrow where the compass was. The arrow should point in the
same direction as the painted end of the compass needle.
3. Move the compass toward the middle of the magnet. When the needle settles, note its direction and
draw an arrow as before.
4. Repeat this as you move the compass to the other end of the magnet.
5. Now start again from a different place near the end of the magnet. Go from end to end at least 3
times. Explore both above and below the magnet.
6. When you're done, your arrows show you where the magnetic field is.
Credits:
ProTeacher Community
29
Electricity
MAGNETIC INSULATORS
Background
Materials:
Let's see if there are magnetic insulators that are analogous to electrical insulators.
Procedure
1. Earlier we found that there are materials that act as electrical insulators that interrupt the flow of
electricity. What did we use to determine whether the electrical current was interrupted?
2. Based on your first exploration of magnets, what are two ways we can determine if a magnetic force
is present?
·
·
·
·
·
·
·
·
1 round magnet
1 compass
notebook paper
brown paper
foil
cotton cloth
felt
plastic bag
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
3. Which of these methods do you think will be more likely to detect a weak magnetic force and why?
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
4. For each of the materials, put one layer of the material between the magnet and the detector. Test tor
the presence of a magnetic force in two ways. Record your observations in the chart on the following
page.
5. Repeat step 4 but put 4 layers of each material between the magnet and detector. Record your
observations in the chart.
6. Repeat step 4 but put 16 layers of each material between the magnet and detector. Record your
observations in the chart.
Conclusion
What can you conclude about magnetic insulators?
______________________________________________________________________
______________________________________________________________________
Credits:
______________________________________________________________________
ProTeacher Community
30
Electricity
MAGNETIC INSULATORS WORKSHEET
31
Electricity
ELECTROMAGNET
Background
Materials:
Here's an example of how electricity and magnetism are closely related.
·
·
·
·
·
·
Procedure
1. Wrap the wire tightly around the whole length of the nail. Wrap all of the wire but about
6 inches at each end.
2.
2. Try to pick up the paper clips by touching them with the nail. What happens?
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
1 three foot long wire
1 nail
2 batteries in holders
1 breadboard
paper clips
push pins
3. Hook up the batteries so that electricity is running through the wire.
4. Try again to pick up the paper clips. What happens? Why?
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
5. Now disconnect the battery and try the paper clips again. Does the same thing happen as in
step 2? What has happened to the nail?
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
Credits:
ProTeacher Community
32
Electricity
CONDUCTORS AND INSULATORS
Background
One thing that makes electricity useful is that not all materials conduct electricity. Materials that do
not conduct electricity are called insulators.
Materials:
·
1 battery in holder
·
1 breadboard
1. Build the simple circuit shown in the schematic below. If you do it correctly, the bulb will light.
·
1 light bulb
2. Replace one of the wires with the 2 wires with clips as shown below.
·
2 wires with washers bag-o-
Procedure
stuff
·
wires with clips
·
push pins
3. Complete the circuit by clipping each of the materials in the bag-o-stuff between the clips.
4. Figure out which materials are conductors and which are insulators. List the materials in the following chart and check the appropriate column. How will you be able to tell which are conductors and
which are insulators?
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
Use the worksheet on the following page to record your findings.
Question
How would you summarize what sort of materials are insulators and which are conductors?
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
33
Credits:
ProTeacher Community
Electricity
CONDUCTORS AND INSULATORS WORKSHEET
34
Electricity
IS ELECTRICITY SAFE?
Background
Materials
Electricity is measured in units of volts, amps or watts. The higher the voltage, the more dangerous the
electricity is.
·
1 breadboard
Procedure
·
2 batteries in holders
·
2 light bulbs
·
2 wires with washers
·
push pins
1.
Build the simple circuit with a single battery. Light the lamp.
2.
Now replace the single battery by 2 batteries with both + signs in the same direction. What
happens?
_______________________________________________________________________________
_______________________________________________________________________________
_______________________________________________________________________________
3. Now reverse one of the batteries so that the two + signs are together. What happens? Why?
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
4. What do you think would happen if you used 4 batteries to light one lamp?
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
Try it with your neighbor.
Questions
Each D-Cell is 1.5 volts. How many volts do two D-Cells have?_______
What voltage is used in your house and school? _______
Credits:
THE VOLTAGE IN YOUR HOUSE AND SCHOOL IS A LOT HIGHER THAN WE USE IN
THESE EXPERIMENTS. NEVER TRY THESE THINGS USING ELECTRICITY FROM A
WALL OUTLET!!
35
ProTeacher Community
Electricity
Selecting Light Bulbs
Light bulbs are getting better. Newer bulbs — like halogen incandescents, CFLs and LEDs — last longer and use
less energy than traditional incandescent bulbs, saving you money on your energy bills. In fact, beginning in
2012, everyday light bulbs have to meet new Department of Energy standards for how much energy they use.
Bulbs that don’t will be phased out over the next couple of years.
Along with this move to more efficient bulbs comes a new way to shop for them.
What Are Lumens?
For years, people have chosen light bulbs by the watt, learning over time about how bright a typical 40-watt or 60
-watt bulb is. But wattage tells you only how much energy a bulb uses — not how bright it is.
With newer light bulbs designed to use less energy, wattage is no longer a reliable way to gauge a light bulb’s
brightness. That takes lumens.
Lumens measure brightness. A standard 60-watt incandescent bulb, for example, produces about 800 lumens of
light. By comparison, a CFL bulb produces that same 800 lumens using less than 15 watts.
How Bright a Light?
This chart shows the number of lumens produced by common incandescent bulbs. If you’re looking to buy a bulb that will give you the amount
of light you used to get from a 60-watt bulb, you’ll now look for 800 lumens.
You can use lumens to compare the brightness of any bulb, regardless of the technology behind it, and regardless of whether it’s a lumens =
brightness
halogen incandescent, CFL or LED. Using lumens helps you compare “apples to apples” when you shop for light bulbs. Once you know how
bright a bulb you want, you can compare other factors, like the yearly energy cost.
A Label to Help You Shop
When you shop for light bulbs, you’ll also want to think about light appearance, or color temperature. Light appearance ranges from warm to
cool. Warmer light looks more yellow, like the light from a traditional incandescent bulb, cooler light appears more blue.
To find out the light appearance of a light bulb, look at the Lighting Facts label on the package. The Lighting Facts label gives you information
you need to compare different bulbs. It tells you:
Brightness (in lumens); Yearly estimated energy cost; Expected bulb life (in years); Light appearance (how
warm or cool the light will look) ; Wattage (the energy used); and If the bulb contains mercury.
The label may include the Energy Star logo if the bulb meets the energy efficiency and performance standards of the Environmental Protection Agency and the Department of Energy’s Energy Star program. For
more on Energy Star standards, visit energystar.gov.
Lighting Facts labels will be on most everyday household light bulbs starting in 2012.
On the Bulb
The number of lumens will be printed on the bulb. If the bulb is a CFL, it may be on the bulb’s base. CFLs
also will include a web address, epa.gov/cfl, for information on safe recycling and disposal. CFLs contain
mercury, so cleanup
and disposal require some care and attention.
36
Learn more about shopping for light bulbs at energysavers.gov/lighting.
Credits:
Federal Trade Commission