The Effect of Using Various Fruits and Vegetables on
the Ability to Power Small Light Bulbs
Jesse Matthews
Takoma Park Middle School 2011 – 12
Abstract
The question of this experiment was how many halves of common types of fruits and vegetables are
needed to light a light bulb, with the potential application of produce serving as an alternative, more
environmentally friendly, energy source. The produce types tested included apple, banana, celery, kiwi, lemon,
lime, onion, orange, potato, sweet potato, tomato, and yellow squash. The hypothesis was that the more acidic
produce types would require fewer pieces of produce than the more chemically neutral ones to light a 1.7 volt
LED light bulb. The setup included a half piece of produce with a zinc screw and non-insulated copper wire
punctured into it in two places. The two prongs emerging from the bulb were then connected, one to the wire
and one to the screw. If the bulb did not light, another piece of produce was added to the setup in series until
the bulb lit. Each produce type was tested five times. Acidic produce types were found to require up to two
pieces fewer to light the bulb than more chemically neutral ones, supporting the hypothesis. Kiwi, lemon, lime,
orange, and tomato required only three pieces on most trials to light the bulb, while celery, onion, potato, and,
surprisingly, apple needed four. Such large amounts of produce to generate about a volt for each half does not
make produce a practical energy source. Perhaps in the future, produce scraps could be tested for their ability to
provide energy to help power equipment at produce packing plants.
Key Terms: Electrical Output, Battery, Produce, Anode, Cathode, Electrolyte
Introduction and Review of Literature
The question studied in this experiment was
“How many halves of common types of fruits and
vegetables are needed to light up a 1.7 volt LED
light bulb?” The findings would hopefully help
answer the question of whether fruits and
vegetables could be used as a source of energy. If
any of the studied produce seemed to provide
adequate energy, it could potentially be an efficient
alternative energy source that would involve little
negative environmental effects, as the produce is all
biodegradable and relatively abundant. If a viable
energy source were found, this could have a
positive environmental effect by helping to reduce
human reliance on oil, natural gas, and electricity.
The hypothesis is that if the electrical output
of apple, banana, celery, kiwi, lemon, lime, onion,
orange, potato, sweet potato, tomato, and yellow
squash are tested, then the produce containing the
more acidic juices, such as kiwi, lemon, and lime,
will need fewer pieces of produce in a circuit to
light up a light bulb than the more pH-neutral types
of produce, such as celery, onion, and potato,
because the acid in the more acidic produce would
TPMS Journal of Science
react with the zinc to produce electricity. Also,
these results are shown in the study “Lemon Cell”
by Jerry Goodisman of the Department of
Chemistry at Syracuse University in that the more
acidic produce produced more electricity than the
less acidic ones.
Every battery contains an anode, which is a
negative electrode, a cathode, which is a positive
electrode, and an electrolyte which pushes the
electrons through the battery. The fruit’s juice acts
as the electrolyte, and the anode and cathode are the
copper wire and the galvanized iron nail,
respectively, in this experiment.
The result,
electricity, is defined as a form of energy that is
expressed in terms of the movement and interaction
of electrons. It can be used as an energy source, as
in this example, to light up light bulbs.
The dependent variable for this experiment
is the number of produce halves need to light up the
light bulb. The independent variable is the type of
produce used, with levels being fruits and
vegetables that are commonly found in grocery
stores year round— apple, banana, celery, kiwi,
lemon, lime, onion, orange, potato, sweet potato,
Page 1 of 7 The Effect of Using Various Fruits and Vegetables on the
Ability to Light Up Small Light bulbs
tomato, and yellow squash. In order to ensure
because it implies that using one of the acidic fruits
accurate results, other variables were controlled
with a nail and wire should result in sufficient
during this experiment.
Controlled variables
electric flow to light the LED bulb.
include the voltage needed to light up each bulb, the
conductivity of each insulated copper wire piece,
Materials and Methods
the tester, the room temperature and humidity, and
In this experiment, the amount of electricity
the juiciness, ripeness, and size of each piece of
that could be produced using various common fruits
produce. LED lights are used due to their low
and vegetables was tested. The materials necessary
requirement of electrical input necessary to power
to complete this testing were one 1.7 volt miniature
them, and the produce were chosen because they are
LED light bulb with base wires attached, three feet
common types, including ones known to have high
of insulated copper wire, three each of twelve
levels of acidity, which is shown to help produce
different fruits and vegetables to be tested (apple,
more electricity.
banana, celery, kiwi, lemon, lime, onion, orange,
A previous study, “Lemon Cells Revisited–
potato, sweet potato, tomato, and yellow squash), a
the Lemon Powered Calculator,” by Daniel J.
cup of distilled water for the control, a towel, a zinc
Swartling and Charlotte Morgan of the Department
coated nails, a wooden surface top, and a kitchen
of Chemistry at Tennessee Technological
knife to cut the fruits and vegetables.
The
University, shows that a single lemon can only
conducting wire was cut into six pieces of
produce about one volt of electricity. Thus, this
approximately equal length to be used to connect
means that one lemon cannot provide enough
the produce pieces to each other and to the light
electricity to power one of the 1.7 volt light bulb
bulb to complete the circuit.
used in the present experiment.
However,
For the first produce type to be tested, a
Swartling and Morgan’s data also shows that
lemon, the kitchen knife was used to cut the fruit in
whenever another lemon is added in a chain to their
half. One half was used for the first trial, and the
setup, the voltage output is increased by about 0.9
other half was saved for later in the first trial, if it
volt, the electrical output of one lemon.
was needed. Additional lemons were also cut in the
Accordingly, three lemons in a chain should be able
case that three or more of the produce halves were
to light up the 1.7 volt LED bulb. Finally, the
needed. All work was done on a wooden surface,
article states that since magnesium is a more active
which did not conduct electricity well and did not
element than zinc, in terms of movement of
interfere with testing the ability of the various
electrons, using magnesium will produce more
produce types to produce electricity. The zinc nail
electricity than using zinc; and, therefore, the same
was inserted into one end of the lemon piece and
number of lemons should produce more volts of
one of the six wire segments into the other end. The
electricity to light the light bulb when using
free end of the wire segment was attached to one of
magnesium instead of zinc.
the base wires of a light bulb. The other base wire
The previously mentioned study, “Lemon
of the light bulb was attached to the zinc nail, which
Cell” by Jerry Goodisman of the Department of
formed an electrical circuit, and it was noticed
Chemistry at Syracuse University, demonstrates that
whether the light bulb was at least partially lit. If it
other types of produce or even water with an added
was, one was recorded for the lemon in a lab book,
acid, for example citric acid, can produce just as
and the first trial was complete. If the bulb did not
much energy as the lemon. Also, it shows that any
at least partially light up, then another lemon half
acid can work well to produce energy in an aqueous
was added with a zinc screw and a piece of copper
solution. Furthermore, this study finds that many
wire punctured into it again. The zinc screw from
other metals besides zinc and copper perform well
one half of the fruit was attached to the copper of
as the anode and the cathode.
Finally, this
another, and the remaining copper wire and zinc
experiment illustrates the potential of producing
screw were attached to the light. It was observed
energy basically by dipping two metals into citric
whether the light bulb was at least partially lit. If
acid and observing how much energy is produced as
so, two was recorded for lemon in the data book,
a result of the electric flow between the two metals.
and the first trial was complete. If the bulb was not
Goodisman’s study is related to the present study
lit, another produce half was attached in a similar
TPMS Journal of Science
Page 2 of 7 The Effect of Using Various Fruits and Vegetables on the
Ability to Light Up Small Light bulbs
manner to how the second produce half was
attached to the first produce half. After completing
the electrical circuit, it was noticed whether the
light bulb was at least partially lit. If so, three was
recorded in the data book and the first trial was
complete. If all three produce halves were unable to
lighten the light bulb, then a fourth half was added.
In this manner, this procedure was repeated for up
to five light pieces, and it was determined whether
one, two, three, four, or five fruit halves were
needed to at least partially light the light bulb. The
setup for three lemon halves is illustrated in Figure
1. Using the same produce halves but in different
spots in the produce, this procedure was repeated
four more times to yield five trials for the lemon.
These five trials also allowed for a mean number of
fruit halves needed for the lemon to be calculated.
Next, five trials were completed for the lime, and
then five for each of the orange, apple, potato,
tomato, banana, kiwi, yellow squash, celery, sweet
potato, and onion.
To serve as a control, approximately a
tablespoon of distilled water was poured onto the
wooden surface, and one end of a wire segment was
placed in one end of the water puddle and the zinc
nail in the other end of the puddle. In this manner,
the puddle of water could substitute for a piece of
produce to see whether zero, one, two, three, four,
or five puddles of water were needed to at least
partially light up the bulb. Water was chosen
because each of the produce types is moist, yet
water is not acidic. The puddles used were dried
using the towel, new puddles were made, and
results were obtained for the remaining of the five
trials using water. This control result provided
baseline information on the ability to light up any
bulbs using the proposed setup without an acidic
type of produce.
Although testing conditions were controlled
as much as possible, various uncontrollable factors
could have interfered with obtaining reliable results.
These factors included differences in conductivity
in various parts of the insulated copper wire, human
error in making electrical connections or reading
results by the tester, and differences in size and
chemical properties of fruits or vegetables of the
same type.
TPMS Journal of Science
Results
The number of produce of a certain type
required to light up a single bulb varied only
slightly among the twelve types of produce tested.
Half of the produce types tested—banana, lemon,
lime, sweet potato, tomato, and yellow squash—
required three produce on each of the five trials to
light the bulb, as can be seen in Table 1 under the
columns corresponding to these six types of
produce, as well as in the colored bars
corresponding to each of these produce types in
Figure 2. Two others—kiwi and orange—required
three produce on at least two of the five trials,
producing a mean over all trials that is close to
three—2.4 and 3.6, respectively, as reported under
the columns for kiwi and orange in Table 1 and the
kiwi and orange sets of colored bars in Figure 2.
The remaining four produce types tested—apple,
celery, onion, and potato—needed four pieces of
produce to light the bulb on each of the five trials.
This result is also seen in Table 1 under the columns
for apple, celery, onion, and potato and the colored
bars for each of these types of produce in Figure 2.
In addition, even five puddles of distilled water
failed to light the LED bulb, strengthening the
argument that the acid in the produce juice resulted
in more electricity produced. Since there was no
number of puddles that resulted in the bulb being lit,
water was omitted from Table 1 and Figure 2.
Furthermore, the number of pieces of
produce of a certain type needed to light up a single
bulb remained most often constant, and if not,
varied only slightly among the five trials for a
single produce type. Of the twelve produce types
considered, only two—kiwi and orange—showed
any variability among trials. Kiwi readings varied
from two to three pieces of produce, and orange
readings varied from three to four pieces of
produce, as shown in the kiwi and orange columns
in Table 1 and the kiwi and orange bars of various
heights in Figure 2. For all other types of produce,
readings for each type of produce remained the
same over the trials, as shown in Table 1 and in the
equal height of the colored bars corresponding to
each produce type in Figure 2.
In conclusion, the number of pieces of
produce required in series to light up the LED bulb
varied only from two to four pieces of produce and
remained constant throughout the five trials for each
produce type in all but two cases. This resulted in
Page 3 of 7 The Effect of Using Various Fruits and Vegetables on the
Ability to Light Up Small Light bulbs
banana, lemon, lime, sweet potato, tomato, and
yellow squash requiring three pieces over all five
trials, and apple, celery, onion, and potato requiring
four pieces over all five trials. Kiwi needed two
pieces on three trials and three pieces on two trials,
and orange needed three pieces on two trials and
four pieces on three trials to produce averages over
the trials of 2.4 and 3.6 pieces of produce,
respectively.
Discussion and Analysis
The data from this experiment show that
with the more acidic types of produce such as kiwis,
lemons, limes, and tomatoes (pH of 2.3-4.6), only
two or three pieces of produce in series were needed
to produce enough electricity to light the 1.7 volt
LED bulb. However, with the more chemically
neutral types of produce such as celery, onions, and
potatoes (pH of 5.6-5.8), four pieces of produce in
series were required to light the light bulb. Other
types of produce with pH values in between the
previous two ranges, such as bananas, squash, and
sweet potatoes (pH of 4.8 to 5.6), were able to light
the bulb with just three pieces of produce in series.
Surprisingly, some fairly acidic types of produce,
such as apples and oranges (pH of 3.6-4.0), needed
four pieces of produce in series, at least during
some trials, to brighten the light bulb. Kiwi (pH of
3.5) needed the fewest number of pieces of produce
to light the bulb, requiring only two pieces in series
for three of the five trials. Apple, celery, onion,
orange, and potato (pH of 3.6-5.8) needed the
highest number of pieces of produce to light the
LED bulb, requiring four pieces in at least three
trials. For the most part, the more acidic produce
types required fewer pieces of produce in series to
light the LED bulb than the more chemically neutral
ones.
This data supports the hypothesis that fewer
pieces of produce would be needed to light the LED
bulb using the more acidic types of produce as
compared with the more chemically neutral types
because the acidity in the produce would react with
the zinc in the circuit to produce more electricity.
Of the produce tested, kiwis, lemons, limes, and
tomatoes have the lowest pH values and required
only two or three pieces of produce in series to
produce enough electricity to light the bulb. Those
with the most chemically neutral pH values, celery,
onions, and potatoes, tied for needing the highest
TPMS Journal of Science
Page 4 of 7
number of pieces of produce in series to light the
bulb. However, produce with pH values in between
these ranges (banana, sweet potato, and yellow
squash) also required three pieces of fruit, and two
fairly acidic produce (apple and orange) needed
four pieces of produce, at least on some trials.
Overall, though, the data support the hypothesis
well.
These results relate to the original purpose
of this experiment, which is to investigate whether
it would be feasible to use fruits or vegetables to
provide power, potentially saving valuable natural
resources.
Based on the observed data, this
proposition appears to be fairly unrealistic since at
least two pieces of produce were necessary in every
trial to produce enough electricity to light a 1.7 volt
LED light bulb. Even the best performer, the kiwi,
produced an average of less than one volt of
electricity per kiwi, and the TI-30 calculator needs
about three volts of energy, or the equivalent of at
least three kiwis. A single AAA battery can
produce approximately 1.5 volts, which seems
much more efficient than employing these fruits.
Pieces of produce could possibly be useful in
supplying power if world resources of other power
sources were drastically low, but, for some reason,
produce was abundant. Still, there would exist
problems with packaging the fruit for placement
near the item to be powered and dealing with
spoilage. Perhaps it would be possible to utilize
inedible or discarded produce parts at canning or
food packaging plants to help power equipment at
these plants someday. Additionally, perhaps other
locations that have a steady supply of produce parts,
like restaurants or farms, could use them to help
power their equipment in the future.
Regarding this experiment, some possible
sources of error include human error, equipment
error, and variability among individual pieces of
fruit of the same variety. Human error could have
occurred in the holding of the electrical wires to the
light bulb, as the connections were dependent on the
tester holding the wires still and in the same manner
for each produce tested. Also, due to the inability
of humans to see faint light, it is possible that the
tester did not notice the bulb barely-lit at some point
but was able to see it only slightly brighter on
another trial. This difference in perception would
have resulted in the requirement of a whole
additional piece of fruit for the one trial as
The Effect of Using Various Fruits and Vegetables on the
Ability to Light Up Small Light bulbs
compared with the other, though the electrical
in electricity production, making use of recyclable
output might have only been minimally different
materials.
between the two trials. Also, the equipment might
have affected the results due to the possibility of the
Acknowledgements
light changing in performance over the trials due to
Special thanks to Mr. Peter Matthews for help with
setting up experiment and collecting data and to Mr. Bryan
usage. After each trial, the equipment was rinsed
Goehring for insightful help and guidance throughout the
clean to try to avoid this error, however. In
experiment.
addition, although many produce types were tested,
results cannot be extrapolated to all produce. It is
References
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different types of acid in the produce types and rank
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the produce according to the amount of a particular
36%20Lemon%20Cell.pdf.
acid that is present in each one. Then the
experiment could be repeated using this information
Hunt, V., Sorey, T., Balandova, E., & Palmquist, B. (2010).
about the produce types. Maybe this information
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could clarify why overall acidity, as measured by
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electrical production potential in this experiment.
http://science.howstuffworks.com/innovation/scienceFinally, one could investigate whether a different
questions/onion-power-ipod1.htm.
material for the nail would result in higher
electricity production. Perhaps even scrap metal
could be used, if it were almost as efficient as zinc
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Page 5 of 7 The Effect of Using Various Fruits and Vegetables on the
Ability to Light Up Small Light bulbs
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Appendices – Supplements (Optional)
Number of Produce of Various Types Needed to Light up a Light Bulb
Trial
1
Trial
2
Trial
3
Trial
4
Trial
5
Mean
Apple
Banana
Celery
Kiwi
Lemon
Lime
Onion
Orange
Potato
Tomato
4
Sweet
Potato
3
3
Yellow
Squash
3
4
3
4
2
3
3
4
3
4
3
4
3
3
3
4
4
4
3
3
3
4
3
4
3
3
3
4
4
4
3
3
3
4
3
4
2
3
3
4
3
4
3
3
3
4
3
4
2
3
3
4
4
4
3
3
3
4
3
4
2.4
3
3
4
3.6
4
3
3
3
Type of Produce Tested
Table 1: Effect of produce type on number of produce pieces needed to light up a light
bulb.
TPMS Journal of Science
Page 6 of 7 The Effect of Using Various Fruits and Vegetables on the
Ability to Light Up Small Light bulbs
Figure 1. Three lemon pieces placed in series to light up an LED light
bulb.
Number of Produce of Various Types Needed to Light up a Light Bulb
Type of Produce Tested
Figure 2: Effect of produce type on number of produce pieces needed to light up a light
bulb.
TPMS Journal of Science
Page 7 of 7 The Effect of Using Various Fruits and Vegetables on the
Ability to Light Up Small Light bulbs