Fruit/Veg Batteries

Overview:

The archaic lemon battery: lemon with a copper and zinc electrode in it. However, there are variables to test that are seldom explored. In these experiments, we will vary the fruit or vegetable used, the distance between the two electrodes, and the surface area of each electrode. Whether or not these variables alter the voltage and amperage produced is the result we wish to test.

Experiment 1: Voltage and Amperage Obtained From Various Electrolytic Substances

Introduction: This experiment is conducted to determine the voltage and amperage created by electrolytic reactions in various electrolytes are different, and if so how much. This shall be conducted through re-creations of the “lemon battery” experiment, in which an anode and cathode come in contact with the electrolyte in order to create electricity. These findings will be quantitative, with the intention that these results become control figures for another experiment, and this experiment is the base for further experimentation. Background knowledge of the acidity and other properties of the tested fruits and vegetables will be compared.

Hypothesis: I hypothesize that there will be a difference that is proportionate to acidity, but a quantitative estimation of variance of said measurements are impossible at this time.

Materials:Digital multimeter, 4 lemons, 4 oranges, 4 potatoes, 4 apples, 1 clean Canadian penny (1997-1999, as the zinc electrode), 1 clean Canadian penny (1977-1996, as the copper electrode), sandpaper (220 grit)

Procedure:
  1. Thoroughly clean each testing lead of the multimeter, ensuring that any residue is removed.
  2. Thoroughly clean the 1997-1999 penny, ensuring that any residue is removed.
  3. Take the sandpaper and sand off all copper on the penny, ensuring that the entire zinc core is exposed on both faces and the sides.
  4. Clean the sanded penny, ensuring that any residue or foreign material from the sanding process is removed.
  5. Insert the two coins entirely into the lemon, parallel and 5mm apart.
  6. Touch the multimeter leads to the two electrodes, negative to the zinc, positive to the copper.
  7. Obtain readings for voltage and amperage as dictated by the multimeter, and record them.
  8. Repeat steps 5-7 with the remaining lemon, oranges, potatoes and apples.
Data:

Set 1

VoltageAmperage
Lemon0.98 V0.94 mA
Orange0.87 V0.92 mA
Potato0.87 V0.83 mA
Apple0.95 V0.37 mA

Set 2

VoltageAmperage
Lemon0.96 V0.98 mA
Orange0.84 V0.93 mA
Potato0.86 V0.83 mA
Apple0.93 V0.33 mA

Set 3

VoltageAmperage
Lemon0.98 V0.94 mA
Orange0.86 V0.92 mA
Potato0.86 V0.81 mA
Apple0.91 V0.39 mA

Set 4

VoltageAmperage
Lemon0.98 V0.95 mA
Orange0.87 V0.92 mA
Potato0.87 V0.83 mA
Apple0.95 V0.37 mA

Electrolyte Comparison:

pH (of liquid)Water content
Lemon2.587%
Orange3.381%
Potato5.580%
Apple4.684%

Results: My hypothesis is generally correct. Each of the different produce used gave vastly differing results. Acidity was generally proportionate to the voltage and amperage produced, with the most acidic, lemons, consistently producing the highest voltages and amperages. However, acidity’s proportion to both voltage and amperage became inconsistent among the other three. Oranges, the second most acidic, showed voltages similar to the potato, the least acidic, both tied for lowest voltages. Oranges did display amperages on par with the lemons, however. Apples, third most acidic, had voltages only just below lemons, but by far the lowest amperage. Water content shows similar correlation. It is impossible to declare direct correlation between voltage or amperage and acidity or water content, as no such definitive connection exists, meaning that a mix of other factors are at work.

Experiment 2: Effect of Distance between Electrodes in an Electrolyte on the Produced Voltage and Amperage in Various Electrolytic Substances

Introduction: This experiment is conducted in order to determine the quantitative effect, if any, the distance between two electrodes on the voltage and amperage produced in various different electrolyte holding fruits. This shall be conducted, again, with the wet cell “lemon battery” experiment. These results will be compared with the control results from Experiment 1.

Hypothesis: I hypothesize that there will be a negative correlation between electrode distance and voltage and amperage produced in which as the distance increases the voltage and amperage decrease, qualitatively in an exponential way. Exact quantitative predictions are currently not possible.

Materials: Digital multimeter, 4 lemons, 4 oranges, 4 potatoes, 4 apples, 1 clean Canadian penny (1997-1999, as the zinc electrode), 1 clean Canadian penny (1977-1996, as the copper electrode), sandpaper (220 grit)

Procedure:
  1. Thoroughly clean each testing lead of the multimeter, ensuring that any residue is removed.
  2. Thoroughly clean the 1997-1999 penny, ensuring that any residue is removed.
  3. Take the sandpaper and sand off all copper on the penny, ensuring that the entire zinc core is exposed on both faces and the sides.
  4. Clean the sanded penny, ensuring that any residue or foreign material from the sanding process is removed.
  5. Insert the two coins entirely into the lemon, parallel and 5mm apart.
  6. Touch the multimeter leads to the two electrodes, negative to the zinc, positive to the copper.
  7. Obtain readings for voltage and amperage as dictated by the multimeter, and record them.
  8. Repeat steps 5-7 with an orange, potato, and apple.
  9. Repeat steps 5-8, inserting the coins 10mm apart.
  10. Repeat steps 5-8, inserting the coins 15mm apart.
  11. Repeat steps 5-8, inserting the coins 20mm apart.

Data:

5mm Voltage5mm Amperage10mm Voltage10mm Amperage15mm Voltage15mm Amperage20mm Voltage20mm Amperage
Lemon0.98 V0.91 mA0.97 V0.28 mA0.95 V0.21 mA0.9 V0.17 mA
Orange0.87 V0.89 mA0.87 V0.3 mA0.87 V0.11 mA0.87 V0.07 mA
Potato0.89 V0.81 mA0.9 V0.59 mA0.9 V0.45 mA0.89 V0.41 mA
Apple0.95 V0.3 mA0.99 V0.23 mA0.95 V0.2 mA0.94 V0.18 mA

Results: My hypothesis was partially correct. Amperage goes down in all cases with distance, most significantly so between 5mm and 10mm. However, voltage stays more or less statistically constant or decreases only slightly. An anomaly common to the potato and apple shows that voltage increased between 5mm and 10mm electrode distance. This suggests an optimal electrode distance. The actual decreases seem to be inversely exponential, being largest the closer the two electrodes are.

Experiment 3: Effect of Surface Area Electrodes in an Electrolyte on the Produced Voltage and Amperage in Various Electrolytic Substances

Introduction:This experiment is conducted in order to determine the quantitative effect, if any, the surface area of two electrodes on the voltage and amperage produced in various different electrolyte holding fruits and vegetables. This shall be conducted, again, with the wet cell “lemon battery” experiment. These results will be compared with the control results from Experiment 1.

Hypothesis: I hypothesize that there will be a positive correlation between electrode surface area and voltage and amperage produced in which as the distance increases the voltage and amperage decrease, qualitatively in a linear way. Exact quantitative predictions are currently not possible.

Materials: Digital multimeter, 4 lemons, 4 oranges, 4 potatoes, 4 apples, 1 clean Canadian penny (1997-1999, as the zinc electrode), 1 clean Canadian penny (1977-1996, as the copper electrode), sandpaper (220 grit)

Procedure:
  1. Thoroughly clean each testing lead of the multimeter, ensuring that any residue is removed.
  2. Thoroughly clean the 1997-1999 penny, ensuring that any residue is removed.
  3. Take the sandpaper and sand off all copper on the penny, ensuring that the entire zinc core is exposed on both faces and the sides.
  4. Clean the sanded penny, ensuring that any residue or foreign material from the sanding process is removed.
  5. Insert the two coins ¼ into the lemon, parallel and 5mm apart.
  6. Touch the multimeter leads to the two electrodes, positive to the zinc, negative to the copper.
  7. Obtain readings for voltage and amperage as dictated by the multimeter, and record them.
  8. Repeat steps 5-7 with an orange, potato, and apple.
  9. Repeat steps 5-8, inserting the coins ½ into the fruits and vegetables.
  10. Repeat steps 5-8, inserting the coins ¾ into the fruits and vegetables.
  11. Repeat steps 5-8, inserting the coins entirely into the fruits and vegetables.
Data
 ¼ Depth Voltage¼ Depth Amperage½ Depth Voltage½ Depth Amperage¾ Depth Voltage¾ Depth AmperageFull VoltageFull Amperage
Lemon0.91 V0.12 mA0.88 V0.31 mA0.89 V0.38 mA0.96 V0.92 mA
Orange0.87 V0.08 mA0.87 V0.45 mA0.87 V0.59 mA0.87 V0.89 mA
Potato0.88 V0.38 mA0.88 V0.41 mA0.87 V0.59 mA0.87 V0.8 mA
Apple0.97 V0.15 mA0.97 V0.24 mA0.97 V0.28 mA0.95 V0.32 mA

Results: My hypothesis was partially correct. As the surface area increases, amperage goes up, but exponentially, as seen in the large increase in amperage from ¾ to full surface area. However, voltage stays statistically constant.