“Toxicity ELECTRICITY! in the city…” – System of a Down
presented by: Jennifer Baker, Pierce Bello, Kim Fields, and Dr. Giovanetti
Name: _____________________
April 26, 2002
GSCI 164 – Dr. Giovanetti
I.
Introduction
II.
Mini Labs: Understanding Electricity and its Components:
a.) Jennifer Baker - Electroscopes and Understanding Charge
b.) Pierce Bello - Water Systems and Understanding Current
c.) Kim Fields – Measuring Current and Voltage
d.) Dr. Giovanetti – Miller Hall as a Complete Circuit
III.
Main Lab: Building Electric Motors
IV.
Conclusion/Hand out Study Guide/Final Remarks
Part II.
Electroscopes and Understanding Charge
Charge up a rod with static electricity (white fur – white rod). Observe what happens
when brought close (not touching). Observe what happens when moved away.
1. Record your observations when the rod is placed near the electroscope.
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2. Record your observations when the rod is touched to the electroscope.
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Charge up glass rod with the other fur. Repeat above.
3. Record your observations when the rod is placed near the electroscope.
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4. Record your observations when the rod is touched to the electroscope.
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Use either rod to charge up the electroscope and place the other rod close but do not
touch.
5. Record your observations and explain.
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Using bar magnets verify the rules for the forces between like and unlike poles. Place one
bar magnet on the rotating holder. Bring other magnets close. Write down a rule to use in
the future so that the rotating magnet can be used to identify N and S poles.
6. Rule.
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Observe the behavior of the bar magnet in the presented demonstration.
7. Why do you think the bar magnet is able to spin?
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Water Systems and Understanding Current
To better understand circuits, voltage, and current, imagine this water model as an
analog to an electric circuit (instructor will be demonstrating). Make predictions on
what you think may be true based on this model.
How can you tell if water is moving?
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What determines which way the water will move?
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What do you think will happen if we pour water through one part of the system?
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Will this system reach equilibrium over time? (What is equilibrium ?)
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Fill in the table with the water analog. (What feature in the water model represents
voltage?)
Electricity
Water Model
volt
resistance
battery (power supply)
current
Measuring Current and Voltage
For current to flow, what do we need (What flows? What do we mean by flowing?)?
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Why do charges flow in this circuit? How do we get current from the battery?
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Activity:
Part I
Circuit:
Turn the power source (battery) on and the voltage as high as it can with the
current all the way down. This means that there is no current; none of the voltage is
being used. Get a 10 to 15-foot piece of copper wire; leaving two lead ends, coil the rest
of the wire up. Connect your wires to the power source (battery) and turn the current up.
What does the current meter show? What does the voltage meter show? Why?
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Now, using sandpaper, rub the protective coating off both ends of the wire so you
can make a metal-to-metal connection with the meter. Again, reattach your wire to the
power source (battery) and turn the current up little by little.
What does the current meter show? What does the voltage meter show? Why?
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Part II
Batteries:
Using a voltmeter and the batteries provided at this table. Connect your red lead
wires to the positive connection of the battery and meter and the black to the negative
connection of the battery and the meter.
Meter Measure
Battery 1
Battery 2
Battery 3
Battery
Configuration 1
Battery
Configuration 2
Battery
Configuration 3
Miller Hall as a Complete Circuit
Take a trip with Dr. Giovanetti through Miller Hall as if it were a complete
circuit. Imagine that you are an electric charge.
Fill in the table with the model analogs.
electricity
volt
resistance
current
battery
Miller Hall circuit
Part III.
Get Your Motor Running!!! :Þ
Putting it together:
1. Insert gold shaft into the hole in the screw about two thirds of the way and tighten
it with the bolt so that it does not move.
2. Wrap your wire, which you used from the previous mini-lab around your screw.
Make sure that you wrap the wire in the same direction or you will change the
magnetic poles of your screw. Make sure that you leave a lead at each end of
your wire.
3. Attach the wire leads to the power supply and provide full current to the coil.
Note which end of the wire is connected to the positive (red) post. Find out which
end of the coil is N and which is S.
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4. Reverse the electrical connections. What happens ?
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5. Verify that you have obtained the correct result by consulting a lab instructor.
6. Stick the cork on the short end of your gold shaft leaving about 1.5 to 2 cm of the
gold shaft showing at the top. Secure the cork to the shaft using a hot glue gun.
7. Place some permanent magnets on the support rods on the side. On one side you
will need to face the magnet so a S pole is pointing inwards and the opposite
orientation on the other side. Ask instructor for details. Be sure you know which
side is N (pointing inwards) and which side is S.
8. Energize coil (put current through it) and observe how it lines up.Do the coil and
magnets line up as expected? Draw a picture and label all the magnetic poles.
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9. Take the two copper plates with the lead wires already soldered to them. Using
the hot glue gun again, glue the plates to your cork making sure that they do not
touch.
10. Connect the leads from the copper plates to the leads at the ends of your wire to
complete that circuit.
11. Take your now complete shaft and insert it into the top holes of the metal arms on
your stand so that the cork with the copper plates is in the same direction of your
metal brushes. You may need to plate a drop of hot glue on the end with the cork
once you have it through the metal arm so that it does not fall out when you spin
it.
12. You need to rotate the copper plates so that they are correctly positioned. Rotate
the motor by hand. Consider how the electric current will flow and what the
resulting magnetic forces will be. Try to predict the best location for the copper
plates with respect to the coil. Loosen the bolt and rotate the coil to this
orientation. Show your instructor.
13. Your motor is now made and ready to be used!!!
Activity: (Motor used in “reverse”. Turn the motor and measure the current.)
What do you think will happen when you connect leads from a power to source to each of
the brushes?
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What kind of generator have you created?
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Electromagnets
Through this portion of the lab you will be able to build your own electromagnet and
explain how it works. The materials you will need are 1 iron screw, a piece of copper
wire the length of the room, a power source, and natural magnets.
Directions:
1. Wrap the copper wire around your screw. Make sure you are wrapping the wire in the
same direction or you will change the magnetic poles of your screw. Leave about 3
inches of wire at either end that has not been wrapped. There is nut on the screw. Be sure
to wrap the wire so that you can loosen and tighten this nut. Be sure and get the instructor
where the nut should be positioned. This will allow you to attach your electro magnet to a
shaft.
2. With a piece of sandpaper sand down the ends of the wire so that the wire is exposed.
3. Attach the ends of the wire to the power source. Ask any of the instructors for
assistance.
4. Turn on the power source. There are two controls. One is for voltage and one is for
current. Your instructor will show you these controls. Set the voltage control to
maximum and slowly increase the current control. Watch the meter (Make sure it is
reading amps). It show you how much current is present in your coil. If the coil becomes
very hot reduce the current. The maximum current will be approximately 5 amps for a
typical coil.
5. Using the natural magnet bring it close to either end of the electromagnet.
1.What interactions do you observe between the natural magnet and the electromagnet?
2. What is the function of the iron screw?
3. What is the function of the copper coil?
4. Draw a picture of the electromagnet, the path of the current, and where the poles are.
1.Briefly describe what occurs when two insulators, a piece of cat’s fur and a plastic rod,
come in contact?
2. What will happen to the end of an iron rod when it is in the presence of a strong north
pole?
A. it will become a north pole
B. it will become a south pole
C. nothing
3. If you have a coil of wire and place an iron rod in the middle it will produce:
A. a large electric potential
B. isolated North Pole
C. electromagnet
4. When you place an iron rod in the center of a coil what happens?
A. it becomes a series circuit
B the strength of the electromagnet will increase
C the strength of the electromagnet will decrease
5. What effect did you see with a coil of wire around the iron screw?
6. A model was discussed using people as charges and the hallways and staircases.
 What feature represented voltage?

What feature represented current?
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What served to model a resistor?
7. You have two 1.5 volt batteries in series connected to resistors as shown in the circuit
below.
R1
R2
R3
a) If the voltage is measured to be 2 Volts across resistor R3
i. What is the voltage across R1?
ii. What is the voltage across R2?
b) If voltage across R1 is measured to be 2 volts,
i. What is the voltage across R2?
ii. What is the voltage across R3?
Circuits
=Battery
Note: When there are two batteries
in series as shown you add the
voltage. Be careful to notice the
orientation. Check to see how to
setup real batteries in this fashion.
ex. 1.5volts + 1.5 volts = 3
Note: When the batteries are
configure as shown the voltage of
one adds as a negative value. Be
careful to notice the orientation.
Check to see how to setup real
batteries in this fashion. Do you
understand why the battery on the
bottom is added as a negative
value?
ex. (-1.5) volts + 1.5 volts=0
=Resistor
R1
R2
=Parallel Circuit
(Voltage measured across each
resistor is the same as the battery
voltage.)
= Series Circuit
(Voltage of battery is divided among the
resistors on any series path. For equal
resistors the voltage is the same across each
resistor. The sum of the voltages will equal
the battery voltage.)
R1
R2
Two resistors in series
Electricity
Helpful Hints
Chapter 7
Electrostatic charge an accumulated electric charge that remains at rest on an object.
Insulating materials like plastic can become charged through contact with other materials.
The build up of charge in this fashion is known as a static electricity. Electrostatic charge
can also be placed on a conductor by transferring the charge. The Van der Graaf
generator places an electrostatic charge on the conducting sphere. Often the static charge
is due to a surplus or deficiency of electrons.
Electric Conductor –
materials where electric charge is free to move throughout
the material. Usually it is the electrons in a conductor that
are mobile.
examples: copper, gold, iron (metals)
Electric Insulator-
materials that obstruct the flow of charge. Charge on an
insulator remains fixed. Electrical current cannot flow
through an insulating material.
examples: rubber, plastic, wood, glass
Electric Current-
Flow of electric charge. Just as you can measure the flow of
traffic on a highway, where the greater the flow of traffic
the more cars pass by, so increased electrical current means
more charge passes a point in a circuit.
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Remember
There are two types of electrical charge, positive and negative.
Like chares repel.
Unlike charges attract.
There are two magnetic poles, north and south.
Like poles repel.
Unlike poles attract.
Material can exhibit magnetic properties. Magnetic materials will act like magnets
in the presents of other magnets. Iron is a magnetic material. The metal screws are
made of magnetic material. You should have observed the metal screws acting as
magnets in the presents of permanent magnets.
Battery Circuits
To make a complete circuit you must have a resistor connected to a power source. For
`2this activity we will learn how to put together a circuit using 1.5 V batteries to light up
light bulbs.
Resistor =
Battery =

Create a parallel circuit using two resistors.
Hint: 
R1
R2
*Measure the voltage of each resistor:
Two resistors in parallel

Create a series circuit using two resistors.
Hint 
*Measure the voltage of each resistor:
R1
R2
Two resistors in series

Create a series circuit using two resistors and two batteries, and draw the circuit
below using appropriate symbols noted above.
*Measure the voltage of each resistor:

Create a circuit using one resistor and two batteries, and draw the circuit below
using appropriate symbols noted above.
*Measure the voltage of the resistor:
What conclusions can you draw from the relationship between the battery voltage
and the resistors?
The Hallway Circuit
*As you walk on the path through the hallway, you are representing an electric charge in
a current flowing through a circuit. In the table below fill in the spaces that each part of
the hallway represents in relation to a circuit.
Electricity
Volt
Hallway Circuit
Resistance
Battery
Current
The Water Model
To better understand circuits, voltage, and current, imagine this water model as an analog
to an electric circuit. Think about how you can connect this model to a circuit.
1) When we pour water into the tube, what do you notice happening?
2) What is happening with the first two tubes?
3) Why do you think the tubes even out differently?
4) What happens to the voltage/height when we add a pump?
5) Why do you think the voltage is different for some of the tubes?
Fun with the Van de Graaff
1) Draw a rough sketch of the Van de Graaff generator. Include the moving
electrons by drawing them on the picture in the appropriate places.
2) Swing the stick with the metal ball near the Van de Graaff generator ball.
What you see is a form of lightning. Briefly explain or draw a picture of
what is taking place with the positive and negative air molecules as
lightening strikes.
3) Now take the plastic ball hanging from the stick, and swing it near the
Van de Graaff generator. What do you see happening?
4) Sketch a picture of this, and label the positive and negative ends of the
plastic ball.
Next we will take a look at another way to produce electrical charge through
static electricity. Predict what charge (+ or -) will be generated through
static electricity for the following materials. The first list of materials will
be rubbed with rabbit’s fur to produce the static charge, while the second list
will be rubbed with a silk cloth. Find a way using the electroscope to check
your predictions.
Rubbed with Rabbit’s Fur:
Material:
Prediction:
Teflon rod
Plastic rod
Glass rod
Wooden rod
Rubbed with Silk Cloth:
Material:
Prediction:
Teflon rod
Measurement
Measurement
Plastic rod
Glass rod
Wooden rod
Describe your procedure. You will probably need help from your instructor.