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Letter 26203 Using fruits and vegetables to produce electricity
Now, for the second step, if the orange juice is a conductive liquid (electrolyte), which it is, the red wire can be removed and the system should still work because electricity can flow from the left electrode through the juice to the right electrode, so we still have a complete circuit. Next, for the third step, you can remove the battery and connect the loose ends of the blue and green wires together. Now you have a complete circuit, but you don't have a battery anymore so the light goes out. Finally, make the electrodes out of two different metals (say copper and zinc) and the lamp will light again. This is because two different metals put into a conductive electrolyte actually comprise a battery. In fact, that's what any battery is: two different metals with a conductive solution between them. So it's not that the orange "produces" electricity, it is that copper plus zinc plus orange juice as the conductive electrolyte make a battery. In this case, the acidic juice allows a small amount of zinc and copper to dissolve in solution. But the zinc has a stronger propensity to go into solution so it drives the copper back out of solution. The net result is that copper dissolves from the copper electrode and deposits on the zinc electrode. Copper metal thus moves from the copper electrode to the zinc electrode (eventually completely coating it). Copper, like all metals (and all materials) has electrons. When the copper dissolves into solution it leaves some of its electrons behind on the copper electrode and dissolves into solution as a positively charged ion, but those electrons that don't travel through the solution with the copper ions, must travel to the zinc electrode through the wire. This movement of electrons is electricity. As I said, some of this will be over your head, but that's as simple as I can make it, and you can absorb what you can from it. The actual amount of electricity produced is very small and you will probably not be able to find even a penlight bulb that you can light with this little bit of electricity, but light emitting diodes (LEDs) require less electricity, so you may be able to light a small one. The liquid crystal displays on electronic calculators use even less electricity (almost none) so you will be able to operate that if you can find one and (with a parent or teacher's help) connect the orange battery in place of the built-in battery. Update to the reply: It may not be there forever, but there is a great youtube video on lemon batteries at youtube.com/watch?v=AY9qcDCFeVI
+++ Hello, Thank you for taking this question and for your help. I am conducting a science experiment where I am conducting electricity with fruit. I cleaned a zinc strip and copper wire with Steel Wool [link is to product info at Rockler]. Then I inserted the zinc and copper into fruit (lemon, lime and orange) about 1 inch apart. Next I hooked up a multi-meter to the ends of the copper and zinc and measured the electricity. I am sure that it had something to do with dissimilar metals as much as it has to do with the different acids in the different fruits. Do you have any input on why the electricity is conducted the way it is? Any help would be great. . Thank you for your help. Colton C
++++ Which fruits and vegetables are most likely to light a light bulb? How does the acidity level effect this? I am doing an experiment to combine the two,what part acidity level plays in electricity. What help can you give in performing this experiment? I am in 9th grade and performing this experiment for a science fair. Jamie S
++++ Hi, I as well am conduction an experiment involving electricity through fruits. I know i must use the zinc and copper. Is there a particular way these strips should be connected to the alligator clips when measuring the voltage of the electricity produced? Missy B
++++ I am a student from XIIth standard. i am doing a project on "Electric charge in fruits and vegetables" it would be a great help if you could kindly give me some information regarding the theory behind the process .how it works? how it conducts? thank you, kasturi thank you sir for your kind assistance but i regret to inform you that i have gone through your homepage regarding my project on "electric charge in fruits and vegetable and found the information insufficient .i wrote the last letter hoping that you could elaborately explain the procedure and the theory behind electric charge in fruits and vegetables. and also how to measure the resistance offered and current flowing through the circuit . I'll be highly obliged if you could reply to my inquiry at your earliest. kasturi b
++++ I would like to know if a penny can be used in a science experiment as a copper electrode to generate my potato battery to work? Thank you so much please reply soon Your dearest, Cassie M
In the USA pennies made after 1982 are copper plated, not solid copper, and they would not be a good electrode. If your penny is solid copper (before 1982) it should be okay. But a piece of copper wire would be even better because copper wire is very pure copper.
I am doing a science project and I need to know, what is the effect of conduction on fruits. Which means I need to know the information required to understand and know which materials are need to test which fruits conduct electricity. So I need to do a experiment on which fruits conduct electricity and know why they do conduct electricity. Thank You :). JONATHAN T
I tried out an orange, a potato, and an apple. none of them made the light bulb react. I used one nine volt battery, copper conductors, and a test light. Why didn't the light react when I placed them correctly? Patrick L
Patrick. Did you wire it per my drawing above? Did it light when you put the red wire back in place?
I am doing a science project on which fruit will conduct electricity the best. I am using an orange, apple, lemon, grapefruit and a pear. How do I do this experiment? Any suggestions would be helpful. Thank you, Scott C Ed. note: It may not be there forever, but there is a great youtube video on lemon batteries at youtube.com/watch?v=AY9qcDCFeVI
+++++ Scott, I am presently assisting my Daughter a 7th grader regarding her lime fruits project. We were able to utilize the carbon and the zinc rod from a discarded size "D" battery and insert it in the lime far a part. Our reading was 1.1 volt using a small digital multimeter, the resistance reading was 2000 ohms taken from analog voltmeter. Finally, we connected two limes in series and we got a reading of 2.2 volts meaning that you can increase the voltage indefinitely and the possibility that it can produce enough current to activate a light emitting diode. P.S. you can purchase LED diode from Radio Shack or from unused electronic toys. Raymond P
+++++ I like your approach of using the carbon and zinc from a battery, Raymond. It helps the kids understand batteries and electricity without having to introduce the new concepts of copper instead of carbon while they're still trying to learn the first concept.
+++++ I wish to know for my project which of these fruits will produce the most energy to a light bulb. an apple, peach, lemon, or a mango. Paul L
Paul, what you are no doubt supposed to do is find out by doing an experiment, not ask for the answer. Watch the youtube video on lemon batteries and do the same stuff with the other three fruits.
+++++ I am a seventh grader and I am doing a potato battery for my science fair project and I want to know what does the potato contain that makes the clock turn on. Also what other things does the potato battery need in order for it to work? Madeleine
+++++ I am doing a science project on which fruit (lemon,mango,kiwi,and apple) will act as a conductor in a simple circuit the best(producing the brightest light). In making my simple circuit I used wire, a flashlight head, a fruit, and 2 D batteries. I had hoped there would be some result in at least one fruit but none produced any light.I'm in sixth grade. Kimberly C
+++++ I have just completed an experiment on fruits and vegetables conducting electricity using pH paper and a volt meter. I found out that the fruits like lime, orange which are acidic conduct electricity the best. But I had found that 2 vegetables, ( potato and tomato) had low acidity but conducted electricity well. Why is this the case? Joel N
+++++ Thank you for the information on this site. I am in the 6th grade and I am testing the voltage from different fruits and vegetables for a science project. Your explanation of the chemical process was very helpful. Zach L
+++++ Hello, Jim W
+++++ 1. You can get "zinc anodes" from a boating store. You can also get zinc from a carbon-zinc dry cell battery with some help from the science teacher. The easiest might be to find a galvanized roofing nail. 2. Any fruit or vegetable that is too dry or is not acidic would probably be a poor choice. So would a fruit or vegetable like brussel sprouts, cabbage, or broccoli that isn't solid. Lemon, limes, and grapefruit are probably the best. 3. The currents are very small, so a tiny bulb from a 1-1/2 volt penlight bulb would be best. Even better, as mentioned above, would be an LED (light emitting diode) from Radio Shack, or a liquid crystal display. Any copper wire would be fine.
+++++ In doing the project about which fruit or vegetable would conduct
the most electricity I have a couple questions. Alexia H
+++++ First off, I'd like to thank Ted Mooney, because of his wonderful
entries I am now able to better understand the reasoning behind
"citrus energy". Jeff K
+++++ I'm doing this topic for my Science fair, and my teacher told me
to research Simple cells, but I can't find anything on them! Could
you please give me a brief explanation of what they are and how they
relate to this kind of topic? Nishat S
+++++ I found some info on single cells. Jeff K (returning)
+++++ My science project is called: Fruit Power: Good for more than just food. I understand that I will need to insert two electrons in each fruit I am testing (lemon, orange and grapefruit). I will be documenting the voltage on a multimeter, then documenting which fruit makes the light bulb the brightest. I have found two web sites that I can use for my research but also have to have two book resources. We have gone to the library but cannot find any books with this project. Can you suggest some books I could get? My research paper is due by Wednesday, Dec. 21. Can you help me asap? Thank you. June C
+++++ June, when you say you can't find any books on the project, it is probably because you are narrowing your focus far too much! Your library probably has dozens or hundreds of books that discuss electricity, and one or two of them is what you need. See . . . While your project will hopefully answer the question of whether a lemon, orange, or grapefruit conducts electricity best, if that was its only purpose it would be trivial, trite, and very very silly. Its purpose is actually to help you acquire a deeper understanding of electricity (and possibly physics and chemistry). And, of course, how to conduct science experiments. Ask your librarian for a couple of chemistry or science books at your reading level that discuss electricity, conductivity, resistance, electrons, or ions. Use them to try to better understand for yourself what this project should be achieving, and cite them. Good luck.
+++++ My daughter is a 7th grader & she is conducting the battery & fruit project. We couldn't find a strip of zinc like the materials said we needed, but we used the top from a vegetable can & it seemed to work just as well. We are having a problem finding an LCD clock that fits on one end of the voltmeter, b/c of the size difference. What can we use to replace that, so that we can get a positive result. When we conducted the experiment w/ the lemon we got a great reading, but trying to make it work w/ the clock was something different, which in turn made her teacher say it was incomplete. Needless to say she gave her an extension, but please give us some suggestions in what to use in order to get the result of using the fruit the battery & in turn having something be operated by it. Thank you, Marie W
+++++ Marie, there should be no problem just using this wire to connect anything any way you want. The LCD clock needn't 'fit' on anything, just put a wire between the two things. Got to Radio Shack or a similar place and get a tiny LCD (liquid crystal display). This should cost under a dollar, will require little power to illuminate, and your lemon should be able to do it. But, since I'm a bit worried if your vegetable can lid will produce enough voltage, this gives me another idea, alluded to by Raymond. Why not increase the voltage by using 3 or 4 lemons in series just like several batteries are used in series in most electronic devices? And galvanized zinc roofing nails really would be better than can lids.
Orange battery . does a orange produce enough electricity to light up a LED? Daniel W
++++++ An orange doesn't produce any electricity, Daniel. It provides ions that can conduct electricity. Similar to a cup full of vinegar. LED's vary, and you may need to connect several cells in series to light an LED.
Update: LEDs may vary, but this excellent youtube video says you need 4 lemons in series --
++++++ Does anyone know why pH levels don't effect the voltage produced?
(11th grade, as stated before ;)) Jeff K
++++++ pH doesn't affect the voltage because it doesn't, Jeff. The "half-cell" voltage depends on the metal in question, and the cell voltage is simply the sum of the two half cell voltages. So you can look up the half-cell voltages of each metal, sum them, and it should come out to 0.8 volts. pH is literally "the negative antilog of the hydronium ion concentration". For high schoolers who have studied logarithms, this should be comprehensible. For somewhat younger students who understand the concept of hydrogen and of ions, pH is the concentration of hydrogen ions. For younger students still, it's how acidic the solution is, with 0 being fully acid, 7 being neutral, and 14 being fully alkaline.
We are making a science fair project about fruit (and veggie)
batteries and we think we know everything we need to know about our
topic. We connected everything as we have seen in before and from
what our resources have shown so we were sure we were doing
everything right but we cant even get a current to flow through our
wires and food.Can you help us? The science fair is in 5 days! Lauryn H & Tara A
++++++ Please follow our illustration and explanation above, and tell us at what step the electricity no longer flowed.
++++++ I am also doing and experiment using a potato as a conductor and I was wondering if the size of the potato will effect the length of time it will power a clock. Does anyone know? Xaijah N
++++++ What is it that you are being asked to determine by experiment, Xaijah? You shouldn't ask for the result of the experiment before you do it, and then try to make your experimental results match the result you are "supposed to get". That is "junk science" and your teacher would fail you. At least we think s/he would :-) It would be a good experiment to see if the size of the potato effects the length of time the clock will run. I don't think it will.
++++++ No You're right that wasn't really what I was trying to ask, but I did the experiment and found that the size doesn't really matter, or it would take longer to determine this than I had time for. Xaijah N
(returning)
January 12, 2009 Hello, Jordan W
Hi. My name is Wendy and I'm helping my son work on his 5th grade
science project. He is trying to determine which fruit or vegetable
produces the greatest electrical charge. He understands that the
fruit or vegetable acts as the battery in his experiment by using a
copper penny and zinc nail to make a complete circuit. However during
testing to determine how many micro-amps are produced when a penny
and a zinc nail are inserted into a lemon and potato, the potato
produces a much larger charge but, won't sustain the charge like the
lemon does. We get readings of about 150 micro-amps with the lemon
and 235 with the potato but, the potato keeps losing it's voltage and
discharges quickly. We have inserted both the copper and zinc one
inch apart from each other on both the potato and lemon during the
test. Can you help us understand why the potato won't sustain it's
charge like the lemon does? Does it have something to do with how the
conductive electrolyte differs in the potato to make it decrease it's
power so quickly? My son wants to say that the potato creates a
larger electrical charge than a lemon but, all the experiments we've
looked at on line always point towards the lemon or citric acid
fruit. Wendy S
January , 2009 Hi, Wendy. If you have a bucket of water to water your flowers, you can choose to pour it slowly for a relatively long time or you can choose to pour it fast for a shorter time. But the bucket goes empty so you can't choose to pour it fast and for a long time :-) The fruit or vegetable is not the battery. The copper and the zinc and the fruit together are the battery. Copper metal moves from the penny to the zinc in two "halves": positively charged copper ions flow through the fruit from the penny to the nail and negatively charged electrons (the electric current) flow through the wire from the penny to the nail. The total amount of electricity available is limited by the penny losing its copper plating or the nail becoming completely copper plated because once both electrodes are covered with the same metal you no longer have a battery. Regards,
January 21, 2009 Re: Wendy's letter, I understand from all I have read that all three components make up the battery, but what makes the potato voltage greater than the lemon and as she asked, why does the potato battery lose its charge faster? We are working on the same project for the science fair and I keep reading that the potato puts out more voltage but I can't find out why???? Joe G
January 26, 2009 Hi, Joe. The theoretical voltage available from the copper metal / zinc metal pair is 1.23 volts. Please look up the EMF series and confirm this. If you had a large sheet of copper spaced very close to a large sheet of zinc, with a perfectly conducting acid between them, no resistance in your wiring, and a meter that did not suck up any of your power, that is the maximum voltage you could ever obtain. You say the potato voltage is greater, but I am not at all sure that a potato consistently produces more voltage than the lemon. You need to put numbers on it, repeat the experiment several times, and make certain that you understand the difference between voltage and amperage before your question can be answered.What did you read for each in 5 trials? The potato could be bigger, allowing more electrolyte to carry the current. Cut it to 1/4 its size and measure the voltage again; the penny & nail could have been closer together; the wires could have been shorter, etc. I explained why the battery loses its charge faster if it's producing more current by speaking of a watering can: it holds only so much water, so the faster you pour, the sooner it will be empty. You have only so much surface on your nail and penny, the faster the copper ions move towards coating the zinc, the sooner it will be coated. Regards,
January 27, 2009 I'm Doing fruit batteries as my project, and i powered up a calculator, with 1.42 v. However, whenever i try to power up my clock, with all of my fruits (5.65 v. altogether) it doesn't power up. Whenever i test, or put the test leads on the clips from the fruits, when its on the clock, it only says 0.52, can you help ? Jacob T
January 27, 2009 Hi, Jacob. Liquid crystal displays like on calculators require very very little current (a dime-sized watch battery can power a watch and its LCD display for a year or more). You haven't told us anything about this clock, but it appears that it requires more current than your fruit batteries can generate. Voltage is similar to water pressure, while current is similar to the flow rate of water. A garden hose may have as much water pressure as a good sized waterfall as long as you let very little water flow out of it. But you can't power a big water wheel or electric turbine with a garden hose, and you may not be able to power your clock with your fruit battery. Fruit batteries generate about 0.8 to 1.0 volts, so it sounds like you are hooking up about a half dozen in series to get 5.65 volts. You can also connect fruit batteries in parallel to get more current. Regards,
March 18, 2009 My 4th grader is doing a project to determine which fruit (apple, lemon, grapefruit, or banana) will conduct the most electricity. We used a digital multimeter (set to vDC) to measure the voltage across the fruits between one zinc and one copper strip inserted about 1" apart. We found that the apple consistently had the highest readings. We had expected the citrus fruits, due to the high acidic content, to be the best conductors. Perhaps these were just some very juicy apples, but shouldn't the acids be better conductors that the alkalines? My son has written his conclusion that alkalines are better conductors and I'm questioning if this is problematic. Please advise any suggestions. gwen syzdek
March 26, 2009 Hi, Gwen. I was not aware that apples are alkaline. Did you test
them with pH paper, or research the matter to be sure that statement
is true? But alkalines can be excellent conductors. Regards,
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