Electric Motors: The Green Machines!
It is very important for students to understand that scientists and inventors come
from all backgrounds. History teaches us that many scientists did not do well in
school, and that they needed an alternative education to succeed in life.
Michael Faraday received his education through on-the-job ("hands-on")
training, and became one of the world's most famous "experimental" scientists.
In the first part of the lesson students will learn Faraday's law of electromagnetic
induction during the assembly of an electric generator. The second part of the
lesson examines illustrations of a variety of power sources that can be used to
operate generators and electric motors.
3-2-1 Classroom Contact #19 "More Power To You"
Students will be able to:
- Retell the story of the person who invented the first electric generator
- Cite and demonstrate the law of induction
- Assemble and test an electric generator to demonstrate Faraday's Law
- Demonstrate how energy moves a coil inside the magnet of a generator
- List examples of power sources that can operate a generator
- Draw a picture demonstrating understanding of different power sources
running a generator
- Compare a generator with a motor and judge their effectiveness.
- paper for drawing and writing answers
- Activity Sheet: "Electric Motors: The Green Machine" (Located at the end of the
To make the generator:
- copper wire (#24)
- neon lamp
- 4-inch steel nail
- plastic straw
- small bar magnet
- Current - flow of electricity
- Coil - loops of wire that receive the current
- Turbine - a wheel-like machine that turns a generator
- Electric generator - a machine that produces electricity from magnets
- Electromagnet - the combination of a coil and a magnet
- Power source - form of energy that can do work
- Electric motor - a machine that changes electricity into mechanical power.
The teacher will set up the twin coil swings to demonstrate how electricity is
created in a wire by moving a magnet. Thrust one magnet back and forth
through the first loop. Ask the students to explain what makes the coils swing,
and allow them one or two minutes to write an answer to this question. Tell
them to be prepared to share their answer with the class.
TEACHER: Let's examine what you think makes the coils swing. A man by the
name of Michael Faraday was the first to try to answer this question. In 1832, he
said that electricity is generated in a wire whenever a magnet passes it. His
ingenious idea became Faraday's Induction Law, but it was really by accident
that he made this discovery. Michael did not go to high school. Instead he was
trained as a bookbinder, starting at the age of 14, for 8 years, then became a lab
assistant in a large university. Most of the time he was trying to convert
magnetism to electricity. In the lesson today, we will explore this relationship
between electricity and magnetism -- the E and M connection -- and then we'll
build a generator. Later on, we will use some power sources, such as a battery,
to turn over a motor of your own creation! OBJECTIVE 1.
TEACHER: (The teacher points to the demonstration.) The first loop is an electric
generator like the one Faraday made in 1832. It converts mechanical power to
electrical power. The second loop is a motor, and it converts electricity to
mechanical power, such as in a car motor. We need to learn the difference
between these two machines.
It is very important to give students a focus for viewing. This helps them focus
their attention on the lesson objectives. This way students learn that the video
is not solely for their entertainment.
TEACHER: Let's watch a video showing
cast member Stephanie making electricity, using her personal, home-made
generator. Later on, she will show us different power sources we can use to run
our generators and motors.
TEACHER: How can I make electricity? Watch the video now and be able to
explain how electricity is created.
START video on the title "More Power To You."
PAUSE video after you hear, "Didn't I tell you it was simple."
TEACHER: List two different ways to make electricity. (You make electricity by
moving a magnet past a wire. Or, by moving a wire past a magnet. It doesn't
matter which one moves. The ignorant wire can't tell the difference!) Ask a
student to demonstrate the generation of electricity with a wire and a magnet.
We are observing Faraday's discovery of making electricity using magnets. Why
isn't it practical to make electricity this way? Watch the video carefully to learn
why not? OBJECTIVE 2.
PAUSE video after you hear the sentences: "You need a steady flow of
electricity. You need a generator."
TEACHER: Why isn't it practical? (Electricity comes in spurts. The lights in your
house would go on and off, on and off.... That's very annoying!) What do you
need to make a steady flow of electricity? (A generator.) Scientists call this flow
of electricity "current." Write "current" on the chalkboard. Ask a student to recite
the definition. To see how a generator produces a steady current, observe
Stephanie in the video as she shows you how a generator works to produce a
STOP video after you hear the words, "After a while your arm gets really tired."
TEACHER: What happens when the loops of wire turn inside the magnet? (It
makes a steady current of electricity, according to Faraday's famous law.)
Scientists have a fancy word for loops of wire -- they call it a coil. (Write the word
"coil" on the chalkboard.) Where does the current of electricity go from the coil?
(Through the wires and then into the light bulb, which lights up!) What does
Stephanie use to turn the wire inside the magnet? (Kid power -- she used her
own muscle power.) Did she produce a steady flow of electricity? (Yes.) How
much electricity? (Enough to light up the little bulb.)
Building an E-M Generator
TEACHER: Let's use Faraday's law of making electricity, and make a toy
generator. You will need the following materials: a coil of wire, a bar magnet, a
4-inch steel nail, a plastic straw, and a neon lamp. Your challenge is to
construct a generator from these materials and make enough electricity to turn
on a small neon lamp. Do the following: Make about 50 turns of bare wire
around a straw to make a coil. Insert a steel nail through the coil. Connect the
leads of the coil to the neon lamp. Then, stroke the magnet back and forth
across the coil. When the neon lamp glows, you have made electricity from an
"electromagnetic generator," or E-M generator for short. How else can we make
electricity? (According to Faraday's induction law, you can also move a wire
past a magnet.) Allow students 10-15 minutes to construct their generators.
Display them around the classroom for everyone to observe. Construct a large
banner with Faraday's famous Induction Law: "Electricity is generated in a wire
whenever a magnet moves past it." OBJECTIVE 3 & 4.
Power Sources: Here comes the Sun!
TEACHER: Think about why your generator is not practical. (Because it does
not make enough electricity to run the lights in your home or your TV set. And,
after a while your arm gets really tired from turning the generator.) So, what do
we use to make all of the electricity we use everyday? (A bigger generator!)
Instead of kid power, what do we use? Let's make a class list of what we can
use. (Water power, steam power, solar power. Ask a student to go to the
chalkboard and start to prepare the list with the help of the whole class.)
Scientists have a word for all of these things, such as kid power, which are able
to turn or do work on the generator. They call them power sources. (Write
"power sources" at the top of the list and define it.)
Touring Electric Power Plants
TEACHER: Let's go back to the video to check our list of power sources. We will
be going on an electronic field trip to Las Vegas to check out one of the world's
largest power stations.
START video as Stephanie says, "So, what do we use to make all of the
electricity we use every day?"
PAUSE video after you hear the words, "So what
keeps the lights on in Las Vegas? Water power from Hoover Dam, that's what,"
with a picture of Hoover Dam.
TEACHER: What turns the generator -- spins the coil of wire inside the magnet?
(Running water -- water power! Point to "water power" on the class list.) What
name is given to the wheel-like machine that turns the shaft inside the
generator? (A turbine. Point to the needle (the shaft) in the toy generator.) How
can we make more electricity for Las Vegas? (Increase the water flow at
Hoover Dam. That turns the turbine faster and makes more electricity.)
REWIND video to the start of the animated sequence.
TEACHER: Let's observe again how water power works. Listen carefully this
time for the different parts of the water powered generator.
PAUSE just after you hear Stephanie explain how water
TEACHER: You are to draw a picture on a sheet of paper showing how
electricity is made from water power. Label the turbine, the shaft, and the
generator. Ask a volunteer to draw the water-powered electricity-making
machine on the chalkboard. Although Faraday's discovery was at first taken
with a grain of salt, today all our electric power is generated by moving giant
coils of wire near magnets. It is amazing that just by our connecting copper wire
and steel magnets in a power plant, falling water can rotate turbines which
make enough electricity to light up all of Las Vegas and other big cities many
miles away! What can you use for wind power? (A windmill.) Let's observe
Miguel, Stephanie's assistant in the field, as he explains how wind can make
electricity -- down on the "wind farm" in California.
PAUSE video at the end of the electronic field trip.
TEACHER: How can wind make electricity? (The wind turns the blades of the
windmill, known as the turbine, which in turns spins the shaft that turns the coil
inside the magnet, known as the generator, and it produces the electricity.)
Draw a second picture on a sheet of paper that shows the parts of the wind-powered electricity-making machine. So, wind can make electricity, and water
can make electricity. How can steam make electricity? Set up an experiment to
show that steam can be produced from different fuels, such as lamp oil, natural
gas, and alcohol. Let's watch the video to observe how oil power works.
PAUSE video at the end of the field trip to the oil power plant.
TEACHER: How does oil make electricity? (Oil is burned to heat water which
makes steam. Steam moves the turbine blades that turn a shaft inside the
generator. The shaft spins the coil of wire inside a magnet in the generator that
produces a current of electricity.) After the electricity is produced, where does it
go from there? (It goes up to the high tension wires. Draw a third picture that
shows how electricity is made from burning oil. Allow students 1 or 2 minutes
to complete their drawing.) There's more than one way to boil water to make
steam. Instead of oil, what other fuels did we say you can use to make
electricity? (Natural gas, coal.)
TEACHER: These fuels are called "fossil fuels" because they come from dead
plants or animals that were buried in the ground and became fossils. Scientists
call fossil fuels "buried sunshine" because plants make their food or fuel from
the sun's power, then die and get buried. Which fuel is buried sunshine --
sunflower oil or motor oil? (Motor oil, because it comes from buried plants or
animals.) Like sunflower oil, motor oil is really sun oil. Instead of using buried
sunshine or "sun oil," we are going to find out how we can use the sun itself to
make electricity. Let's take a field trip to the Solar I Power Station in California
with fieldguide Miguel. Be able to tell me what Miguel has to say about sun
power (solar power).
PAUSE video at the end of the electronic field trip.
TEACHER: How does sun power make electricity? (Large mirrors reflect
sunlight and focus it to heat water in a receiver. Steam made by the heated
water flows through pipes under pressure to the turbine and turns its blades.
The turbine is attached to the turning shaft that goes into the generator, and
that's where the electricity is produced.) Take two minutes to draw a picture that
shows the parts of the sun power station. We'll then watch the video to review
what we have learned so far.
STOP video at the end.
TEACHER: So, let's review. How can you make electricity with a magnet and a
wire? (Move a wire past a magnet or a magnet past a wire. This is Faraday's
Induction!) How can you make a steady flow of electricity? (By spinning a coil
inside a magnet. The two parts make up a generator.) What are some power
sources used to run a generator? (Running water, steam, fossil fuel, the sun.)
List the steps in making electricity from a power source. (For example, wind
turns the turbine that rotates a shaft inside the generator where the electricity is
made by a coil spinning inside a magnet.) Check the class list of power sources.
Did we miss one? OBJECTIVE 5 & 6.
The Clean, Green Machine
TEACHER: Let's identify clean power sources for making electricity. From the
class list, give me examples of clean power sources? (The sun, wind, or water.)
Why is oil not a clean source of power? Burn the kerosene lamp oil for students
to observe the smoke. (It makes air pollution.) Is a battery a clean power
source? (Yes, it is a power source, since it can be used to make electricity. If it
does not contain toxic chemicals, then it is a clean or nonpolluting source. A
battery is really a "chemical generator.") What about a solar cell? (Yes, it
makes electricity without polluting the environment. It's a clean, green
TEACHER: Can we use our clean, chemical generator -- the battery -- to make
a motor? The worksheet titled "The Green Machine" [located at end of lesson]
shows you how to build and operate a motor. Use this diagram to build the
motor and make it work.
Teacher circulates among the students to assist them in building the motor.
Allow students to experiment with a second magnet to see if they can change
the speed of the motor. Ask them to try placing a pair of attracting magnets on
top of the battery, in place of the single magnet. Allow students 15 minutes to
build their motors.
TEACHER: Compare your toy motors and generators. List the differences
between the two. (It is suggested that the teacher make a Venn diagram to show
the comparison. Generators make electricity, but motors produce motion or
mechanical power. Also, generators use a power source to move a turbine or
mechanical power that is converted to electricity. Electric motors are the
opposite: they use electricity as a power source, such as batteries.) So, as you
can see, a motor is really a generator running "backwards"! Now, use your
knowledge of electricity and magnetism to explain what makes the twin coils
swing? If you understand the E and M connection, you can see what turns on
the generator and the motor. Power is being converted back and forth from
electricity (E) to magnetism (M). OBJECTIVE 7.
ASSESSMENT: Evaluate student learning by demonstrating the twin coil
swings and asking students to write one paragraph explaining what makes the
coils swing. Ask them to make a sketch of the twin coil swings and label the
following: motor, generator. Allow them one or two minutes to write an answer
to this question.
Arrange a field trip to an electric generating station. Assign homework for each
student to prepare at least five questions about electricity to ask the tour guide
during the visit.
Arrange a field trip to an electrical company. Inquire about careers in electricity.
History and Science:
1. Research the English scientist Michael Faraday. Write a report on his life as
a boy and the events that led him to become a great scientist and inventor.
2. Research the variety of motors that were built since the eighteen hundreds.
Compare the power output of gasoline motors with electric motors.
Art and Science:
Design and construct a chemical generator -- a battery. Test the battery using
a small bulb lamp.
Math and Science:
1. Students measure the current and voltage produced by their toy generators.
Compile the data as a whole class, and compute the average and the range of
the data. Compare their values to that of commercial electric generators.
2. Students construct two toy electric motors, using one and two magnets.
Compare the voltage and speed of the motors. Graph the results.
Careers in Science, Math, and Technology:
1. Research careers in electricity and electronics.
2. View other ASSET courses on careers in science, such as Futures and
Futures2, Discovering Women in Science, and BreakThrough, Interactions:
Real Science Real Math, #4, "Solar Power."
Electricity, Chapter A16, "Electric Forces and Fields." Seattle, Washington: Videodiscovery, Inc., 1992.
CD Rom/Computer Software:
Time Shift Radio, Tom Snyder Productions, 1995.
Click here to view the
worksheet associated with this lesson.
Master Teacher: Steve Martin
Lesson Plan Database
Thirteen Ed Online