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Challenge Your Students to
OR
Hans Christian Oersted
Make Motors
Challenging STEM Activities Based on FUNdamental Science Concepts
Digital copies of this document can be obtained at: http://www.sciencescene.com. \
Developed by: Dr. Michael H. Suckley
Michael Faraday
Background:
In 1811, Danish schoolteacher Hans Christian Oersted discovered the first evidence of the relationship
between electricity and magnetism. His discovery was quite accidental. Oersted laid a current-carrying wire
beside a directional compass. As he did so, he noticed the compass needle turning. He immediately
recognized that a magnetic field must have been emanating from the wire therefore causing the compass
needle to be deflected. He also realized that the magnetic field had to be produced by the current flowing in
the wire because, when the current was turned off, the needle ceased to be deflected. Oersted's
discovery of the relationship between electricity and magnetism led to other discoveries:
1. Electric charges attract or repel one another.
2. Magnetic poles attract or repel one another.
3. An electric current in a wire creates a circular magnetic field around the wire.
4. A current is induced in a loop of wire when it is moved towards or away from a magnetic
field, or a magnet.
By applying Oersted’s key principles and developing additional principles Michael Faraday was able to
make a functioning electric motor in 1832. This handout presents the application of Oersted and Faraday’s
discoveries in the making of simple motors which have three components, the battery, a piece of wire and a
magnet. Using these variables eight different motors will be made that can be used for student research
projects. These motors illustrate the same physics that are found in all electric generators and electric motors
today and are remarkably inexpensive to build.
Please note: Magnets have been known to cause injury or even death if swallowed. Do not allow magnets to snap
together, or snap against metal objects, as they are easily chipped. Magnets are also capable of nipping your skin if
allowed to snap together.
Observing the Shape of the Magnetic Field Near a Wire Carrying a Current
1. Bend a piece of copper wire into the shape shown above. Glue the bottom wire onto a small piece of foam
core board.
2. Place an AA battery at the separation between the two ends of the wire. Keep a little space between the
ends of the wire to act as a switch. The battery holder is a small piece of PVC pipe.
3. Place compasses, as shown, around the wire and observe the compass needles.
4. Close the battery switch and observe the compass needles. Describe the pattern or shape created by the
compass needles indicating the shape of the magnetic field.
Observing the Interaction of a Magnetic Field and a Wire Carrying a Current
1. Bend a piece of copper wire into the shape shown to the right. Glue the
bottom wire onto a small piece of foam core board.
2. Place a AA battery at the separation between the two ends of the wire.
Keep a little space to act as a switch. The battery holder is a small piece
of PVC pipe.
3. Hang a magnet suspended from a string from the top wire. Slide the
magnet near the wire.
4. When the switch is closed (wire is touched to the top of the battery) you
will notice the creation of the electromagnetic field and its effect on the magnet.
The Eight Motors
1. The Dangler – Spin the Magnet
Materials: AA Battery, 1 Neodymium Magnet dia 5/8X1/8", paperclip OR flat headed wood screw,
12 cm #22 wire - ends clean
.
Procedure:
1. Place a neodymium magnet on a flat table.
2. Carefully place a flat headed wood screw perpendicular in the center of the magnet.
3. Lower the battery onto the paperclip or wood screw. The paperclip or wood screw will attach to the
bottom of the battery since the battery's casing is ferromagnetic.
4. While holding one end of a copper wire against the top terminal of a AA battery brush the other end of
the wire against the rim of the hanging magnet. This completes the circuit, causing the current to flow
and the disc to spin.
The Dangler Motor Explained
So what causes the magnet to spin? Upon brushing the wire against
the rim of the magnet, current flows over its chrome-plated surface to
the central connection point at the top of the attached woodscrew. As the
magnet conducts the current from the battery, a force between the
magnetic field of the magnet and the magnetic field produced by the
flowing current acts on the magnet causing the magnet to spin.
The direction of current flow is indicated by the purple arrows. The
magnetic field lines are illustrated in blue. The flow of electricity
through the magnet produces a magnetic field which creates a force
perpendicular to this flow. The force indicated by the green arrow and
causes the magnet to spin.
Make Motors
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2. The Dangler – Spin the Power Source and Magnet
A modification of the motor uses the spin of the battery and the magnet.
Materials: AA Battery, 2 Neodymium Magnets dia 5/8X1/8", 12 cm #22 wire - ends clean
Procedure:
1. Place a neodymium magnet at each terminal/end of a AA battery.
Magnets should have like(same) poles facing one another.
2. Attach a paperclip to one end of the wire.
3. Suspend the battery and magnets from the paperclip attached to the wire.
4. Touch other end of wire to the dangling magnet to complete the circuit.
3. The Dangler – Spin the Wire
A modification of the motor uses the spin of the wire.
Materials: 1 AA Battery, 1 magnet, copper wire
Procedure:
1. Place a neodymium magnet on a flat surface
2. Place the AA battery on the magnet.
3. Make a shape out of #14 bare copper wire. The shape must
reach from the top terminal to the bottom magnet. Balance the
shaped wire on the top battery terminal and touch the bottom magnet to complete the circuit
4. The Roller
A modification of the motor uses the spin of the dangler to become a roller.
Materials: AA Battery, 2 magnets, copper wire
Procedure:
1. Attach two neodymium disc magnets (.5” x .25”) to either terminal of an AA
battery so that like poles are facing.
2. Place a short piece of copper wire formed into the shape indicated and glue a
toothpick across the ends of the wire. (the toothpick helps align the wire)
3. Place the ends of the wire onto the upper rim of the magnets to complete the
circuit allowing the current to flow. When placed on a smooth horizontal
surface, the forces acting on each magnet cause the Roller to roll across the
surface.
5. The Train
A modification of the motor moves the battery and magnets.
Materials: AA Battery, 2 magnets, #20 bare copper wire
Procedure:
1. To make The Train you will need some coiled bare copper wire. This
can be made by wrapping #20 bare copper wire around a 3/4”
wooden dowel.
2. Use a AA battery with magnets thin enough to fit through the coil.
The magnets snap onto both ends of the battery. For this to work the
magnets must be attached to the opposite ends of the battery with the
same polarity (N or S) touching the battery.
3. Note: the direction The Train is pushed is a function of the direction
of the flow of the current. You may have to switch the direction of the battery and magnets so that the
train will be pushed into the coil and will not be pushed out of the coil.
4. If you insert the battery and magnets inside the coil The Train will move. The electromagnetic force
generated by the current moving through the coil pushes against the magnets attached to the battery,
pushing the battery through the coil of wire.
5. Connect both ends of the coil together and the battery will travel in the loop until the battery is drained.
Add a small hill or even another battery/magnet set and observe.
Make Motors
Pg. 3
The Train Explained
The drawing, to the right, shows the magnetic field of the coil. At the ends of
the coil, where the field lines diverge, a bar magnet will be either pulled into the
coil or pushed out of the coil depending on which way you insert the battery and
magnets.
The magnets of the train are made of a conducting material which connects the
battery terminals to the copper wire. The battery, magnets and copper wire make
a circuit that generates a magnetic field just in the vicinity of the battery.
The magnets have been carefully aligned so the force on both magnets point in the same direction and
result in the movement of the magnets and battery. But as they move, the magnetic field moves with them
and you get a constant motion. If you flipped the two magnets at the ends of the battery the battery and
magnets would move in the reverse direction. If you flipped only one magnet, the two magnets would then
be pulling/pushing in opposite directions and the battery wouldn't move.
6. The Railgun
The railgun is a device used for accelerating an object by running electric current along a pair of rails.
This could be applied to a train car moving down a set of tracks. When large amounts of power are used, the
railgun becomes a potent weapon. The following activity uses a smaller amount of power ( a 9-volt battery)
and is safe for classroom use.
Materials:
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Base made from a piece of cardboard or wood about 14 inches by 8.5 inches (legal paper cardstock).
Two strips of aluminum foil (OR use aluminum tape), 1 inches wide, and 2 inches longer than the base.
A 1-inch length of steel wire, such as from a coat hanger. (The best is 3/16” iron rod)
2 magnets,
9-volt battery and two clip leads
Procedure:
1. To make the railgun track attach the aluminum foil strips about a half inch apart to the base and smooth,
with fingers, to remove wrinkles, Fold the ends of the strips around to the back of the base to make it
easy to clip on the leads for the battery.
2. To make the projectile, file the ends of the metal rod/wire flat. This will allow the magnets to stick flat
to the ends of the wire axle. If the filing is done carefully to make the flat ends perpendicular to the wire,
then there will be less wobbling as the magnets travel down the rails. Place the
magnets on either end of the wire axle with the same poles facing each other.
3. Attach the battery, as shown above, and place the projectile on the railgun track.
If the gun shoots the wrong way reverse either the battery or the magnets.
The Railgun Explained
Current flowing through the inductor creates a magnetic field. The current flowing through the field
creates a force on the projectile. If one portion of the projectile is free to move, it will move away from
the power source.
Make Motors
Pg. 4
7. Basic Electric Motor
Materials
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1 AA battery
29.0 cm #26 wire
2 1.25 cm pieces of Duct Tape or #27 rubber bands
2 paperclips
1 magnet
1 1.5x4.0 cm Cardboard with double stick tape
Procedure
Rotate
1. The armature supports are made out of two paperclips.
Lift and
rotate
Unbend the paper clips by lifting and rotating one end to
rotate
form a small loop in the center of the paper clip. The loop
can be made larger by inserting a toothpick while bending.
2. Use tape or a #27 rubber band to hold the paper clips on the
ends of the battery. When using the rubber band place the
Finished
rubber band around the battery, lengthwise, and then insert
support
the paperclips. Make sure paperclips are attached so that Hold here
they are level.
3. Place a piece (1.5-cm by 4.0-cm) of self-stick tile or cardboard with double-sided tape to the bottom of
the battery for support.
4. The armature is made by wrapping 30 cm. of #26 insulated enameled copper around a AA battery.
Wrap the ends of the wire around the coil two times tightly, leaving the ends sticking out like handles.
Hold one end of the armature in each hand and spin adjusting making sure that the coil is balanced
and rotating smoothly.
Scrape off ALL the coating off
Scrape HALF of the coating off
5. The wire used to make the armature has a coating on it. This coating must be carefully removed to allow
the electricity to flow. You can either scrape or use sandpaper to remove the insulation. Scrape off all
the coating at one end and the top surface only at the other end. Scrape off enough length of the wire so
that the scraped area can make contact with the armature supports placed on the battery. Remember:
make sure that the coil is balanced and rotates smoothly.
6. Place the armature in the paper clip supports. Make sure that the scraped area of the armature touches
the paper clips. If the scraped area of the armature does not touch the paper clips readjust or re-scrape
the wire.
7. Finally, place the magnet on the top of the battery, and center the coil over it. If everything is just right,
giving the coil a little spin will cause it to start rotating.
8. Rotate and/or adjust the loop until it begins to work. Don't fret if it doesn't work the first time. This
simple motor can be a bit finicky to get working, and you will probably have to adjust the end of the
wires a bit until the coil is balanced.
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Basic Electric Motor Explained
The paperclips and wire create a closed loop circuit that can carry current. Current flows from the negative
terminal of the battery through the circuit, to the positive terminal of the battery. The current travels through
the coil which is called the armature of the motor. This current induces a magnetic field in the coil.
Magnets have two poles, North and South. North-South interactions stick together, whereas north-north
and south-south interactions repel each other. Because the magnetic field created by the current in the wire
is not perpendicular to the magnet on the battery, at least some part of the wire’s magnetic field will repel
and cause the coil to continue to spin.
The insulation was removed from only one side of the wire to make a break in the circuit. The current
causes the magnetic field to pulse on and off producing the rotation of the coil. Whenever the current is
moving through the coil it produces a magnetic field. The coil is repelled by the stationary magnet’s magnetic
field. When the coil isn’t being actively repelled (during those split second intervals where the circuit is
switched off), momentum carries it around until it’s in the right position to complete the circuit, induce a
new magnetic field, and be repelled by the stationary magnet again. Once moving, the coil will continue to
spin until the battery is dead.
8. Benjamin Franklin’s Static Motor
This motor uses static electric charges for power. The ability to produce a static charge varies with humidity.
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5.
Background
Ordinarily, an atom is neutral. This means that it has an equal number of electrons and protons. If an atom
gains electrons, it is said to be negatively charged. If an atom loses some electrons, it becomes positively
charged. Atoms with like charges repel each other, while atoms with unlike charges attract each other.
Procedure
1. Screw a drywall screw into the block of wood OR insert a straw into a predrilled hole in the block of
wood then insert a Philips head screw into the top of the straw.
2. Carefully position the tip of the pushpin or thumbtack over the exact center of the bottom of the cup.
Slowly push the pushpin or thumbtack straight down. Twisting will help the tip penetrate the cup. Note:
the cup, in the kit, already has a hole placed in it.
3. Place the rubber band around the outside of the cup as shown.
4. Insert a Mylar® strip (vane) under the rubber band and then bend it at the rubber band to create a crease.
Evenly insert the remaining vanes, for a total of four, under the rubber band.
5. Assemble the motor by placing the point of the pushpin into the cross on the head of the screw.
6. Rub the Styrofoam block or PVC pipe with the wool for 20 to 30 seconds then place the Styrofoam on
one side of the motor and the fabric on the other. Additional adjusting of the wool and Styrofoam/PVC
pipe will help the motor spin faster as the vanes come close to new areas that have not yet lost their charge
imbalance.
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Pg. 6
Benjamin Franklin’s Static Motor Explained
Reflective Mylar® has a thin coating of aluminum, which is a conductor. When a Mylar® strip moves
near a negatively charged object, some electrons will move toward the Mylar®. If the object is positively
charged, the electrons move from the Mylar® toward the positively
charged object. Either way, the Mylar® will end up with the same
charge (+ or -) as the nearby charged object. A Mylar® strip, which
can rotate, will be repelled from the charged object since like (same)
charges repel each other. The strip is now strongly attracted to the
oppositely charged second object. When a charged strip moves near
the second object some electrons are again transferred. The Mylar®
strip now acquires the same type of charge as the second object. The
strip is now repelled from this second object, but will be attracted to
the first charged object. The Mylar® strip continues rotating due to momentum. When a Mylar® strip
rotates near the first charged object, the process repeats. The attractive force changes to a repelling force
and the Mylar® strip rotates away, repeating the cycle.
Extensions
The following provides suggestions to turn this activity into a Challenge or Engineering Project.
1. Have students build motors with varying number of
vanes and use to do the activities. The drawing, on
the right, indicates the placement for rotors
containing 1–6 vanes. Place cup on drawing and
mark placement of vanes.
2. Explore the size of the materials that are rubbed
together to generate a charge imbalance. Determine
the optimal size.
3. Explore other materials that can be rubbed together
to generate a charge imbalance. Look-up the
“Electrostatic Series” for ideas.
4. Create different shaped vanes to create new
versions of the rotor.
5. Instead of placing both the fabric and Styrofoam
near the motor substitute a finger for one item.
What happens differently?
Workshop Resources
Materials:
CMS Magnetics: ..............................N45 Disc Neodymium Magnets Dia 5/8X1/8" NdFeB Rare Earth Magnet
ETA hand2mind (Copper Wire) - http://www.hand2mind.com/item/copper-wire-bare-20-gauge-100/4436
Aluminum Foil Adhesive Tape - 1" - http://www.ebay.com/itm/Aluminum-Foil-Adhesive-Tape-1-x-55yds25mm-x-50m-Silver-Ship-From-USA-/162014371835?
Background:
Visit http://www.raft.net/raft-idea?isid=408 for "how-to" video demos and more ideas!
Basic background information on static electricity – http://www.sciencemadesimple.com/static.html
Benjamin Franklin and his electric motor – http://www.todaysengineer.org/2002/Aug/heritage.asp
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