Download Are Metals Donors?

Are Metals Donors?
Serena Debesai
Takoma Park Middle School 2011-12
Abstract
In order to understand, whether metals are donors, the testable question, “Are metals donors?” was
tested. Based on background research from previous experiments such as William J. Beatty, Robert Vann de
Graff, Micheal Faraday, and Jean Picard, and scientific facts, the hypothesis, that metals would have a negative
charge was formed and not be donors. An electric field detector was used to read the charges of five metals and
the five metals and non-metals, or the independent variables, were also assembled. The metals tested were,
copper, gold, lead, and silver. The non-metals tested with them were cotton, silk, polyester, and paper. Each pair
of materials was rubbed together, and then held next to the gate wire of the FET on the electric field detector.
The LED, then either dimmed, signifying a negative charge, or brightened, signifying a positive charge. This
was repeated five times for the five trials and the charges were recorded on a table. The mode of the data
collected showed that the metals in all the tests had a negative charge, and all the non-metal materials had a
mode charge of positive. This data supported the hypothesis that metals are not donors, and would have a
negative charge. Possible major implications, of this experiment are using the electric field detector to detect
dangerous electric fields, and help to determine what materials to use when building things. Search terms for
this article are ‘electric field detector’ and ‘are metals donors’.
Introduction and Review of Literature
For millions of years, people have been
fascinated by static electricity and electric and their
strange properties. One question many have
wondered is “Are Metals Donors?” The answer has
solved many problems and led to the development
of modern technology and energy distribution,
which is why I am interested in this topic. Learning
more about electricity has also been a goal for me in
this experiment. Electricity has also never been one
of my major areas of knowledge, which also
contributes to the reason why I have expressed
interest in this topic. In this experiment, the
association between the charge of the materials and
materials used to create them were tested.
Electricity is a force of nature that is
originated from charged particles, which are an
element of atoms, the smallest units of matter.
Atoms are made up of protons, neutrons, and
electrons. Protons and neutrons make up the core of
the atom, the nucleus, while electrons linger
outwards whirling around the nucleus. Electrons
have negative charges, because they contain 2/3 unit
of negative charge but only 1/3 unit of positive
which unbalances the charge in the negative
charge’s favor. In contrast, protons, the opposite,
contain a positive charge, and 2/3 unit of positive
charge but only 1/3 unit of a negative charge
therefore making its overall charge positive.
Takoma Park Journal of Science
Neutrons on the other hand possess no charge; their
negative and positive charges balance out leaving
them with no charge. Electricity must also flow in a
current. This phenomena, creates the electric field,
which occupies the area around a current. In this
experiment, the affect of different materials on the
size of an electric field was tested. Pairs of materials
that generate static electricity such as copper and
cotton gold and silk, lead and polyester, and silver
and paper were tested, the control level being
copper and cotton. The size of the electric field that
each pair of materials create was measured in volts
by using a volt meter and the field was detected by
using an electric field detector
Metals are conductors, which are materials
that allow electricity to flow through them freely.
Low resistance, which means to have a weak
tendency to fight electricity, is the reason why they
allow electricity to flow through them so freely. To
have extremely low resistance means that the
material is an extremely good conductor. Metals
atoms contain electrons that are loosely attached to
the atom, allowing them to jump from place to
place. But in order to remove electrons from a metal
would take gazillions of Newton’s of energy. This
is because the sea of electrons in a metal is very
dense and not very compressible. So it was
predicted that all metals in this experiment, copper,
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Are Metals Donors?
gold, lead, and silver would not be positively
charged not give of electrons easily.
The actual electric field detector used
three main components, the LED or light emitting
diode, FET or field effect transistor, and the ninevolt battery. The field effect transistor, a transistor
that relies on electric fields for conductivity in a
channel with one charge carrier in a semiconductor,
has three leads. These are the drain, D, the gate, G,
and the source, S. The source is where the majority
charge carriers enter the channel and the drain is
where they exit from the channel. The FET has a
channel of N-type semiconducting materials,
semiconductors with electrons as their majority
charge carriers, which allow the electrons to carry a
current. When a battery was connected to the FET,
a voltage was applied to the N-type semiconductor.
When an FET is on the device, the maximum
current flows when there is no negative field. But,
in a small region the middle of the N-channel is Ptype semiconductors. Surrounding this is a
depletion zone with very few electrons, so when the
size of the depletion zone increases, the resistance
increase. When a negative electric field is present,
the depletion zone is enlarged so the current is
decreased which turns of the LED and the circuit.
So when a positively charged material is placed
near the electric field detectors antenna, the LED is
brighter, but in contrast, the negatively charged
material will result in the dimming of the LED.
Many have explored in electric fields and
static electricity such as Robert Van de Graaff and
Micheal Farday. In 1831, Michael Faraday
conducted an experiment where he designed a
dynamo disk, which turned other energy such
sources into electric power, out of conductive
materials, and it produced electric energy. Metals
were a conductive material used. The Van de Graaff
electrostatic generator, developed by Robert Van de
Graaff in 1929, another experiment similar to that
of Faraday’s used conductive metals to generate
large electric fields that produce enough power to
fling a proton at a high speed. Van de Graaff’s
generator is essentially a giant metal lollipop, which
crackles with charge. In the body of the generator is
a brush and a rubber or fabric conveyor belt. The
brush picks up sensitive protons, or positive electric
charges, and carries them up with electrodes in the
bulb leaving the bulb with a positive charge.
Takoma Park Journal of Science
Continually, positive charge is being stacked on top
of one another until a strong enough potential
energy is created and a proton can be shot at high
speed. This experiment explained how objects
become charged. It also showed how nonmetals
were used to carry the protons or positive particles
to the top, not the negative.
William J. Beaty’s, a research engineer
was another who experimented with electric fields
and electric field detectors. In 1987, he made an
electric field similar in design with the one used in
this experiment. He could sense electric fields and
determine which object was positively or negatively
charged.
Jean Picard, another scientist also
conducted experiments using electrostatics and
electric fields. But, this only happened when the
mercury moved outwards. Many others tried this
but were unsuccessful. Bernoulli in the year 1700
used a large glass vial that had been pumped free of
its air with an air pump. He then sealed the vial with
a cork and wax and called it perpetual phosphorus.
Years later in 1706, Francis Hauksbee used this
experiment but went farther and used a globe
evacuated of air with a little bit of mercury in side
and attached to a driving belt. Future experiments
added sheepskin outside of the glass globe and then
adding amber inside. This was the birth of
electrostatics. These experiments helped determine
the idea of testing metals. Michael Faraday and Van
de Graaff used conductive materials in their
experiments, so metals were used. The design of the
electric field detector used in this experiment was a
design similar to William J. Beaty’s.
Based on all the data that was gathered
from previous studies and research such as Robert
Van de Graaff, Micheal Faraday, Jean Picard, and
William J. Beattys experiment, I can predict that the
metals will be negatively charged because metals do
not give of electrons easily. Robert Van de Graaff’s
electrostatic generator also showed how conductors
were used to produce large electric fields. The
generator for one was made entirely out of metal,
which is a good conductor, and used nonmetals to
carry positive charges. William J. Beatty’s
experiment also helped me to determine that metals
would be negatively charged because he explained
that metals do not give of electrons easily.
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Are Metals Donors?
Jean Picard and Michael Faraday’s
experiments also showed how electric fields rely on
conductors. Faraday discovered that electric
currents can be created by placing conductors in an
electric field showing one relationship between the
two. The fact that copper is a good conductor
supports the hypothesis that was determined for this
experiment. Therefore, my experiment will prove
my theory.
Materials and Methods
In order to answer the question “Are Metals
Donors?” an electric field detector was built. This
allowed the scientist to determine which material in
each pair of materials what material was positively
or negatively. To test that each result was accurate,
five trials were conducted. Then data was recorded
on a table presenting the size of each field, the trial
number, and which material was positively charged
or negatively charged.
As nature is, many things affect the course
the others take. The same rule was applied in this
experiment. In order to keep the results accurate and
credible, a warm and steady temperature of 72
degrees F was used. Colder weather conditions
could result in more conductivity, resulting in
inaccurate data. The same sample of materials were
also tested and never changed for each trial. This
was to prevent results from becoming inaccurate
due to a different sample, which could have had a
slightly different size, shape or another factor that
could have affected its conductivity in a negative or
positive way.
To begin this experiment, I assembled all
materials necessary for this experiment. This
included, one 1”x1”x1” cube of copper, one 2”x2”
square if cotton, one stick of pencil lead, one silver
earring with a diameter of 2 centimeters, one gold
ring, one 2”x2” square of pure polyester, one 2”x2”
square of paper, and one 2”x2” square of pure silk.
One light emitting diode, one “3x2” breadboard,
one nine volt battery, one N-channel field affect
transistor, and one battery connector were also
gathered and were used to create an electric field
detector. To build the field detector, the red wire or
the positive wire of the battery connector was
pushed into hole E2 on the breadboard, while the
negative or black wire was pushed into hole E4 on
the breadboard as seen on the picture below. The
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battery was not connected until the detector was
completely assembled to avoid burning out the field
affect transistor or the light emitting diode. The
middle lead or the source of the field effect
transistor was connected to the red battery lead by
inserting it into hole A2 of the breadboard. The
drain lead from the field effect transistor, or the
leftmost lead from the flat side of the FET was also
inserted into the breadboard but in hole A3.
Because the gate wire was the antenna, it was bent
away from all the other leads and not attached to the
breadboard. The light emitting diode lead closest to
the “flat region” on the diode was connected to the
negative battery wire hole, hole C3 of the
breadboard, and to the negative or black wire, and
the by being inserted into hole A4 on the
breadboard. The battery was connected and then
taped down to secure it.
Figure One: Diagram of Electric Field Detector
Once the field detector was built, the scientist
began the actual experiment. Copper and cotton,
two of the materials used in this investigation and
the control variable, were rubbed together for ten
seconds in order to create static electricity. Each
material was held up to the antenna or gate wire of
the electric field detector, and it was recorded on a
data table whether the material dimmed the light or
brightened it. This step was repeated five times for
accuracy before I moved on to the next pair of
materials, which were gold and silk. The two
materials were rubbed together, held up to the
antenna and noted for either dimming or
brightening the light as well. These steps were
repeated for the next pair of materials, lead and
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Are Metals Donors?
polyester, and silver and paper. The results for each
material were recorded on the table below as the
experiment was being performed, along with the
mode, as either positive or negative. For each trial
the result correlating with the material in the
material column was the result for that material. For
example, copper and cotton the first materials had
“Negative, Positive”, meaning that copper was
negative
and
cotton
was
positive.
Results
Once the
materials
were
tested, it
was
found
that the
mode for each metal was negative, and for each
non-metal material in each pair was positive. For
Trial One, copper, gold, lead, and silver were
negatively charged and cotton, silk, lead, and paper
were positively charged. During Trial Two, it was
found that copper, gold, lead, and paper were
negatively charged, but silver, cotton, silk, polyester
and paper were positive. For Trial Three, gold, lead,
silver, and cotton registered as positive, and copper,
silk, polyester and paper were found to be positively
charged. Trial Five showed that cotton, gold, lead,
and silver were negatively charged, and copper,
silk, polyester, and paper were positively charged.
Copper, silver, lead and gold all had a mode of
negative, whereas cotton, paper, polyester, and silk
all had a mode of positive. As shown in the data
table, for all trials, only lead stayed negative the
whole time. In contrast, gold, copper, and silver all
were negative during at least one trial. Only gold
was positively charged twice. Only one trend could
be observed. This was that as shown on the data
tables the mode for all metals was negative and the
mode for all non-metal materials was positive.
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Discussion and Analysis
The results found in this experiment show that
all the metals tested had a mode charge of negative,
and all of the non-metal partners had a mode charge
of positive. Based on this trend of data, it be can
concluded that the data collected was a result of the
fact that it is very difficult to separate electrons
from metals because it takes a high amount of
energy. But metals are
typically
positive
ions. Only lead had a
consistent charge of
negatively and its
non-metal partner had
a consistent charge of
positive. The other
materials were not
consistent.
I can
speculate that this is
due to sources of
error.
Mechanical
error, human error,
weather conditions,
and the fact that
gloves were not used
and the gate wire of
the FET was touched often could have contributed
to these results. The electric field detector may not
have read the charge correctly, or I may have not
read the charge correctly. Weather conditions may
have also affected the outcome of this experiment,
so the charge of the material was wrong. Gloves
were not used in the experiment, so human hands
may have interfered with the charge of the material.
The gate wire of the FET was also touched, and this
could have interfered with the reading of the charge
of each material. But, the outcome of this
experiment still supported the hypothesis. The
hypothesis was that the metal objects would be
negatively charged, and the non-metal objects were
positively charged, therefore, metals are not donors.
The testable question, which was “Are Metals
Donors?” was answered in this experiment. It was
found that the mode charge for all metals was
negative, and positive for non-metal materials.
Therefore, metals are not donors, because they do
not give of electrons. If they did, then the metals
would have been positively charged. In other
experiments, it was found that the metals would be
negatively charged. For example in William Beaty’s
experiment, it was also shown that metals would not
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Are Metals Donors?
be donors. Further related experiments include
adding a wire antenna to the field detector, to see
how well it improves the sensitivity of the charge
detector. Changing the humidity to see how it
affects the charge of the materials. Building the
circuit with a solder to make connections is another
option. Charging an object and then testing what
materials best keep it charged is also another
experiment. This experiment can help mechanics
and scientists around the world determine what
materials to use when building things, or help detect
dangerous charge in areas.
Appendices-Supplements
Mode of Material Charges
(Positive, Negative)
Material
Acknowledgements
Thanks to:
Mrs. Epling for all of the wonderful help
Asmeret Aylay for getting materials
References
Dreier, D. L. (2008). Electrical Circuts: Harnessing
Electricity (A. Watcholtz,
Ed.). Minneapolis, Minnesota : Compass Point
Books.
Physics Today. (2006, September). The Birth of
Electrostatics. Physics Today,
59(9), 104. Retrieved from
http://web.ebscohost.com/scirc/
detail?vid=6&hid=15&sid=98b01c2a-dd9d-46739446-c6492299ac80%40sessionmgr10&bdata
=JnNpdGU9c2NpcmMtbGl2ZQ%3d%3d#db=sch&
AN=22265415
Mode
Copper, Cotton
Negative, Positive
Gold, Silk
Negative, Positive
Lead, Polyester
Negative, Positive
Silver, Paper
Negative, Positive
Figure Three: Summary Data Table: Are Metals
Donors? This table shows the mode charges of each
material
Sreenivasan, B. (2010, December 25). Modeling the
Geodynamo: progress and
challenges. Current Science , 99(12), 1739-1750.
Retrieved from
http://web.ebscohost.com/scirc/
detail?vid=15&hid=15&sid=98b01c2a-dd9d-46739446-c6492299ac80%40sessionmgr10&bdat
a=JnNpdGU9c2NpcmMtbGl2ZQ%3d%3d#db=sch
&AN=60464906
Wolfson, R., Proffessor, Ph.D. (2007). Electricity.
In World Book: Vol. 6. World
Book E6 (2007 ed., pp. 191-205 ). Chicago: World
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Detector [Article]. Retrieved January 19, 2012,
from http://www.eskimo.com/~billb/emotor/
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