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Running Head: PROBE DISTANCE AND VOLTAGE
The Effect of the Distance between Metal Spheres on the Amount of Voltage Passed
Between the Spheres
Example 4
Liberty Union High School
Friday, March 25
Mr. King
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PROBE DISTANCE AND VOLTAGE
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Abstract
This experiment was conducted to look at the effect of the distance between two
electrodes on the amount of voltage that passes between the electrodes. The primary
materials required for this experiment are a gas tube transformer, a mutlimeter, two
copper wire electrodes, a ruler, and a screwdriver. The hypothesis for this experiment is
if a gap between two electrodes is made larger then less voltage is transferred between
the two electrodes. The manipulated variable is the distance between the two electrodes.
The responding variable is the amount of voltage passed between the two electrodes.
The levels are the electrodes touching, the electrodes .3 centimeters apart, .6 centimeters
apart, one centimeter apart, 1.2 centimeters apart, and 1.5 centimeters apart. There are
four trials for each level. The constants are the number of trials, the transformer, a
method used to find the voltage, and the location where the experiment was conducted.
The control is the two electrodes touching.
The results of the testing indicated that as the distance between the electrodes
increased, the amount of voltage that passed between the electrodes increased. The mean
voltage was zero when the electrodes were touching, 584 volts at .3 centimeters apart,
902 volts at .6 centimeters apart, 1,188 volts at one centimeter apart, 1,477 volts at 1.2
centimeters apart, and 9,065 volts at 1.5 centimeters apart. The experiment data did not
support the hypotheses that if the electrodes are farther apart than the voltage would be
lower. The results in this experiment were consistent with tests by Jochen Kronjaeger.
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Table of Contents
Abstract……………………………………………………………………………………2
Introduction………………………………………………………………………………..4
History……………………………………………………………………………………..4
Significance………………………………………………………………………………..5
Facts……………………………………………………………………………………….6
Methods and Materials…………………………………………………………………….8
Results……………………………………………………………………………………..9
Conclusion……………………………………………………………………………….11
Tables…………………………………………………………………………………….13
References………………………………………………………………………………..14
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Introduction
Electricity has fascinated people for ages. From the invention of the light bulb to
the luxury of the LCD television, we cannot imagine our lives without electricity. But
what makes those things work? It is the simple science of the circuit and the power of
voltage. Even the well-known insulator, air, has difficulty stopping the mighty voltage
from pushing the current through a circuit. Under the right conditions, voltage, although
decreased, can break through a gap of air.
History
There have been many scientists who have studied electricity. Two well-known
physicists from Germany lead the way in the understanding of circuits and voltage. The
first is Georg Ohm, who was a teacher at Jesuit College in Cologne (Georg Simon Ohm,
2000). The second is Gustav Kirchhoff who, in 1845, developed his circuit laws while he
was a college student (Gustav Robert Kirchhoff, 2002).
In 1827, Georg Ohm’s experiments determined that there is a relationship
between voltage and resistance (Ohm's law, 2010). “Ohm’s law, in electricity,
experimentally discovered relationship that the amount of steady current through a large
number of materials is directly proportional to the potential differences, or voltage, across
the materials” (Ohm's law, 2010). Ohm determined a mathematical formula for his law,
which is that voltage equals resistance times current (Ohm’s law, 1996). The standard
unit of measure of resistance was even named after him; it is called an ohm (Ohm's law,
1996).
In 1845, Gustav Kirchhoff experimented with electrical circuits and developed
two theories that are called Kirchhoff’s laws (Kirchhoff’s circuit laws, 2009). His first
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circuit law, also known as Kirchhoff’s current law, states that “the amount of current
flowing towards a point should be equal to the amount of current flowing away from that
point” (Kirchhoff’s circuit laws, 2009). Kirchhoff’s second circuit law, also known as
Kirchhoff’s voltage law, states that “the sum potential difference (drop or gain) in a
closed circuit is zero” (Kirchhoff’s circuit laws, 2009).
These two scientists developed their theories in the 1800s. Since then, there have
been many scientists who have experimented with electricity. Many more have invented
valuable electrical tools. Despite the new knowledge in electricity, the theories of Georg
Ohm and Gustav Kirchhoff have not changed and are still used today (Ohm's law, 2010;
Kirchhoff’s circuit laws, 2009).
Significance
Electricity affects just about every part of a human’s life in today’s modern times.
Electricity provides power to many of the tools most people uses throughout the day.
From the alarm clock that wakes a person in the morning to the television a person
watches at night, electricity makes it all possible.
Conducting experiments with electricity helps people to understand how
electricity works. Experiments can deepen knowledge about how circuits function, how
voltage is measured, and how voltage can vary in a circuit. Studying electricity is
valuable to everyone, especially to one who wants to be an engineer. The hypothesis for
this specific experiment is that if a gap between two metal spheres was made larger less
voltage is transferred between the two spheres.
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Facts
All substances are made up of atoms (Riley, 1998). Small particles, called
protons, neutrons, and electrons, are in the atom. The electron, which has a negative
charge, spins around the proton, which has a positive charge, and the neutron, which has
no charge. Most atoms have a balance of protons and electrons; this means the atom is
neutral. Sometimes an object becomes charged and the atom is not balanced. A charged
object tries to attract other charged particles so it can become balanced again. These
charged particles cause electricity (Woodford, 2010).
Electricity is energy that has two different forms, current electricity and static
electricity. “Current electricity is caused by the movement of charged particles.” In
static electricity, there is no movement of the charge (Woodford, 2010).
Current electricity flows in a circuit. Circuits are in every electrical device. A
simple circuit has an electrical source, wires, a switch and a bulb. A closed circuit allows
electricity to flow around the circuit; an open circuit does no allow electricity to flow.
Voltage is the energy that makes the electricity flow in the circuit and is measured in
volts (Riley, 1998).
Air is an insulator; another word for insulator is dielectric. This generally means
that voltage cannot travel across an air gap. However, when dielectric breakdown occurs,
voltage can travel through the air gap. This is because “when the voltage becomes
sufficiently high in an air gap, electrons are stripped from the air molecules, ionizing the
air and allowing current to flow.” Lightning is an example of dielectric breakdown (How
far can sparks jump, 2002). The voltage in the circuit is now called dielectric breakdown
voltage (Science Buddies, 2002).
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The understanding of electricity requires the knowledge of several key terms. A
circuit is “a path along which a current of electricity can be made to pass” (Woodford,
1998, p. 30). This experiment will require a circuit. “Current is the flow of electricity in
a circuit” (Woodford, 1998, p. 30). A current will flow through the circuit in this
experiment. Voltage is “the energy that makes the electricity flow in the circuit and is
measured in volts” (Riley, 1998). Voltage will be measured during the experiment. A
voltmeter is an instrument that measures voltage. A voltmeter will be used to measure
voltage in this experiment.
Some additional terms that are important are piezoelectricity, piezoelectric
crystals, dielectric, and dielectric breakdown. “Piezoelectricity is the ability of certain
crystals to produce a voltage when subjected to mechanical stress” (Piezoelectricity –
definition, 2010). A piezoelectric barbecue fire starter will be used in this experiment.
Piezoelectric crystals are a small-scale energy source (Piezoelectric Crystals, 2006). The
crystals in the fire starter will be the energy source. A dielectric is an insulator. Air will
be the dielectric in this experiment. “When the voltage becomes sufficiently high in an
air gap, electrons are stripped from the air molecules, ionizing the air and allowing
current to flow” (How far can sparks jump, 2002); this is dielectric breakdown.
Dielectric breakdown is expected to occur between the two metal spheres.
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Methods and Materials
The approach to understanding electricity and performing an experiment to
measure voltage will require research on the topics of circuits, voltage, and how
electricity passes between objects. Like most electrical research, this experiment will use
a circuit and measure voltage using a voltmeter. The research will require knowledge of
piezoelectricity because the experiment will use a piezoelectric barbecue fire starter as
the energy source. This differs from most circuit experiments that typically use a battery
as the energy source. In addition, the circuit will have an “air gap” between the two
metal spheres to create dielectric breakdown. This also differs from most circuit
experiments that have wires that connect the circuit, meaning that there are no gaps in the
circuit.
The materials required for this experiment are: a barbecue fire starter, a voltmeter,
two metal spheres, modeling clay, electric tape, stiff cardboard, a ruler, and a
screwdriver. The hypothesis for this experiment is that if a gap between two metal
spheres is made larger, then less voltage is transferred between the two spheres. The
manipulated variable is the distance between the two metal spheres. The responding
variable is the amount of voltage passed between the two spheres. The levels will be the
metal spheres touching, .3 centimeters apart, .6 centimeters apart, 1 centimeter apart, 1.2
centimeters apart, and 1.5 centimeters apart. There will be four trials for each level. The
constants will be the number of trials, the starter, method used to find the voltage, and the
location where the experiment is conducted. Finally, the control will be the two metal
spheres touching.
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Results
The effect of the distance between two electrodes on the amount of voltage passed
between the electrodes is summarized in Table 1.1 and Table 1.2. During testing, there
was a need to change the instrument used to measure the voltage. The original plan was
to use a voltmeter; however, the voltage in the experiment was too high and the voltmeter
was damaged. Therefore, an oscilloscope, an instrument used to measure high voltage,
was used to try to measure the voltage. During the testing with the oscilloscope, the
metal spheres were removed because a consistent connection could not be established.
Two copper wire electrodes were used. In addition, when using the oscilloscope, the
voltage readings were inconsistent and difficult to capture. This was due to the
fluctuating charge from the piezoelectric fire starter. Therefore, the energy source was
changed to a gas tube transformer. Because the gas tube transformer is high voltage, a
high voltage probe and an electronic multimeter was used to measure the voltage.
The first test was measuring the voltage with the electrodes touching. The voltage
measurement with the electrodes touching was zero in all four trials. The voltage is zero
because the touching electrodes formed a closed circuit (a complete circuit). No
dielectric breakdown occurred. The range and the mean with the electrodes touching is
zero.
The second test was with the electrodes .3 centimeters apart. The measured
voltage was: 616 volts on trial one, 440 volts on trial two, 684 volts on trial three, and
596 volts on trial four. The range was 244 volts, and the mean was 584 volts. These
results indicate that dielectric breakdown was occurring. A low amount of voltage was
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needed to create dielectric breakdown when the electrodes were .3 centimeters apart.
After this test, there is evidence that the hypothesis may be incorrect.
The third test was with the electrodes .6 centimeters apart. The measured voltage
was: 710 volts on trial one, 872 volts on trial two, 1,006 volts on trial three, and 1,020
volts on trial four. The range increased only a little from the first test to 310 volts. The
mean was 902 volts. More voltage was needed to create dielectric breakdown between
the two electrodes. Results from the third test indicate that the hypothesis is incorrect.
More voltage passed between the electrodes as the distance between the electrodes
increased.
The fourth test was with the electrodes 1 centimeter apart. On this test, over
1,000 volts were needed to create dielectric breakdown. The measured voltage was:
1,080 volts on trial one, 1,044 volts on trial two, 1,272 volts on trial three, and 1,356 volts
on trial four. The range increased only by a few volts from the third test, increasing to
312 volts. The mean was 1188 volts. These results continue to indicate that more
voltage is needed to create dielectric breakdown as the electrodes are moved apart. These
results continue to prove that the hypothesis is incorrect.
The fifth test was with the electrodes 1.2 centimeters apart. The voltage
measurements on this test were very close to the voltage measurements on the onecentimeter test. The measured voltage was: 1,414 volts on trial one, 1,460 volts on trial
two, 1,472 volts on trial three, and 1,560 volts on trial four. The range was 146 volts,
indicating that the results were close the four trials. The mean was 1,477 volts. Again,
these results indicate that more voltage is needed to create dielectric breakdown as the
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distance between the electrodes increase and that the hypothesis for this experiment is
incorrect.
The sixth and final test was with the electrodes 1.5 centimeters apart. On this test
there was no spark created between the two electrodes because there was not enough
voltage for dielectric breakdown to occur. However, there was still a flow of electricity
between the two electrodes. The measured voltage was: 9,240 volts on trial one, 8,540
volts on trial two, and 9,240 volts on trials three and four. At this distance, the range was
the biggest with a difference of 700 volts. The mean was also the highest; the mean was
9,065 volts. Even though there was no spark, this test still indicates that there is a large
amount of voltage passing between the two electrodes.
Conclusion
The purpose of this experiment was to determine the effect of the distance
between two electrodes on the amount of voltage that passes between the electrodes. As
the distance between the electrodes increased, the amount of voltage that passed between
the electrodes increased. The mean voltage when the electrodes were 1.5 centimeters
apart (9,065 volts) was greater than the voltage when the electrode were touching (zero
volts). The data does not support the hypotheses that if the electrodes are farther apart
the voltage would be better. The results in this experiment are consistent with tests by
Jochen Kronjaeger. Kronjaeger found that voltage of 5,000 volts was needed for a
distance of .42 centimeters, 10,000 volts for a distance of .85, centimeters, and 15,000
volts for a distance of 1.3 centimeters (Kronjaeger, 2000). While Kronjaeger’s results
indicate that the amount of voltage that passed between the electrodes increased as the
distance between the electrodes increased, his results show a higher level of voltage at
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each distance. This discrepancy could result from different atmospheric conditions.
Kronjaeger’s testing was in dry air (Kronjaeger, 2000). This experiment was conducted
in a normal household setting, which means there was humidity. Kronjaeger also used
needles as the electrodes (Kronjaeger, 2000). This experiment used copper wire as the
electrodes. Additional studies could be conducted to determine the amount of voltage
transferred between needles using a more powerful energy source with the experiment
being conducted in dry air.
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Appendix A
Table 1.1. The effect of the distance between two electrodes on the amount of voltage
(V) passed between the electrodes.
Distance
Between the
Electrodes
Touching
.3 cm
.6 cm
1 cm
Trial 1
Trial 2
Trial 3
Trial 4
0
616 V
710 V
1,080 V
0
440 V
872 V
1,044 V
0
684 V
1,006 V
1,272 V
0
596 V
1,020 V
1,356 V
0
244 V
310 V
312 V
0
584 V
902 V
1,188 V
1.2 cm
1.5 cm
1,414 V
9,240 V
1,460 V
8,540 V
1,472 V
9,240 V
1,560 V
9,240 V
146 V
700 V
1,477 V
9,065 V
Range
Mean
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Appendix B
Table 1.2. Graph of the data in Table 1.1. As the distance between the electrodes
increased, the voltage passed between the electrodes increased.
9,000
8,000
Voltage (V)
7,000
6,000
Trial 1
5,000
Trial 2
4,000
Trial 3
Trial 4
3,000
2,000
1,000
0
0
0.3
0.6
1
1.2
Distance Between the Electrodes (cm)
1.5
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References
Georg Simon Ohm. (2000). Retrieved from School of Mathematics and Statistics,
University of St Andrews, Scotland website:
http://www-groups.dcs.st-and.ac.uk/~history/Biographies/Ohm.html
Gustav Robert Kirchhoff. (2002). Retrieved from School of Mathematics and Statistics,
University of St Andrews, Scotland website:
http://www-history.mcs.st-and.ac.uk/Biographies/Kirchhoff.html
How far can sparks jump? (2002). Retrieved from Science Buddies website:
http://www.sciencebuddies.org/science-fair-projects/project_ideas/
Elec_p032.shtml
Kirchhoff's circuit laws. (2009). Retrieved from Connexion website:
http://cnx.org/content/m30943/latest/
Kronjaeger, J. (2000). Jochen's High Voltage Page. Retrieved from
http://www.kronjaeger.com/hv/hv/msr/spk/index.html
Ohm's law. (1996). Retrieved from NASA website: http://www.grc.nasa.gov/WWW/k12/ Sample_Projects/Ohms_Law/ohmslaw.html
Ohm's law. (2010). Retrieved from Britannica website: http://www.britannica.com/
EBchecked/topic/426070/Ohms-law
Piezoelectric Crystals. (2006). Retrieved from Renewable Information website:
http://www.greenenergyhelpfiles.com/piezoelectricrystals.htm
Piezoelectricity - definition. (2010). Retrieved from word IQ website:
http://www.wordiq.com/definition/Piezoelectricity
Riley, P. (1998). Electricity. Connecticut: Grolier Publishing Co., Inc.
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Woodford, C. (2010). Experiments with Electricity and Magnetism. New York: Gareth
Stevens Publishing.