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Electricity from fruit (cont'd)



1     2



An ongoing discussion from 2006 through 2016 . . .


(2006)

Q. Orange battery: does an orange produce enough electricity to light up a LED?

Daniel W [last name deleted for privacy by Editor]
- St.Peters, Missouri


(2006)

A. An orange or a lemon doesn't actually "produce" any electricity at all, Daniel. It simply provides a liquid path that can conduct electricity. The difference in electrochemical potential between copper and zinc is what produces the electricity.

LED's vary, and you may need to connect several cells in series to light an LED. This excellent youtube video says you'll probably need 4 lemons in series --

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey



(2006)

Q. Does anyone know why pH levels don't effect the voltage produced? (11th grade, as stated before ;))

I have tried to research this in many places but I am unable to come up with an answer. For my experiment, I took pH readings on several different fruits: lemon, lime, kiwi, grapefruit,and orange. The pH levels varied from 2.4-3.5, but all of the voltages emitted were .8 volts. Any answer would be greatly appreciated, thank you.

Jeff K [last name deleted for privacy by Editor]
student - Milwaukee, Wisconsin


(2006)

A. pH doesn't directly 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, and sum them. In the case of copper and zinc it should come out to 1.1 volts, but you have resistance in your circuit that is lowering this, and/or your voltmeter is drawing enough current to cause these lowered readings.

pH is literally "the negative log 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. Best of luck.

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey



(2006)

Q. I am also doing an 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 [last name deleted for privacy by Editor]
- Prescott, Arizona


(2006)

A. 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 might fail you.

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.

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey


(2006)

! 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)
- Prescott, Arizona



January 12, 2009

Q. 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.

We appreciate your time and consideration.

Wendy S [last name deleted for privacy by Editor]
Mother of 5th grade science student - Crozier, Virginia


January 2009

A. Hi, Wendy. If you have a bucket of water for watering your flowers, you can choose to pour it slowly for a relatively long time until it is empty or you can choose to pour it fast for a shorter time until it is empty. Still the bucket will go 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": the positively charged copper ions flow through the fruit from the penny to the nail and the 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.

So if the current flows faster in one case, it can only flow for a shorter time before the battery goes dead just like the bucket goes empty sooner if you pour faster.

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey


January 21, 2009

Q. 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 [last name deleted for privacy by Editor]
- Mt. Orab, Ohio


January 26, 2009

A. Hi, Joe. The theoretical voltage available from the copper metal / zinc metal pair is 1.1 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 from that particular pair of metals.

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 and the "battery" will be dead.

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey



January 27, 2009

Q. 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 [last name deleted for privacy by Editor]
- Northridge, California


January 27, 2009

A. 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,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey



VOM meter

March 18, 2009

Q. 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 than 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
- Houston, Texas


March 26, 2009

A. Hi, Gwen. I do not think that apples are alkaline. Did you test them with pH paper, or research the matter to be sure your statement is true? But alkalines can be excellent conductors too.

Lye (Drano) is much too strong and much too dangerous to be used in a child's science project, but it is very highly alkaline and an excellent conductor.

Fruits and vegetables contain hundreds of different exotic chemicals including chelators, complexors, sequestrants, surfactants, etc. It's not strictly an issue of acidity. When we don't even know what chemicals are in an experiment, trying to explain their effects on the experiment is questionable. Although using fruits and vegetables instead of controlled reagents can help bring safety into the science department, it unfortunately helps throw science out of the science department :-)

The best thing to do may be to learn how to conduct science projects, and what the scientific method is, and explain what you can, while leaving for later some of the explanations of why certain quirks happen the way they do if there are too many unknowns and variables to confidently explain it. Your son's "explanations" may or may not be correct, but his "observations" are correct, because observations are facts. So have him concentrate on his observations, but go light on conclusions :-)

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey



June 6, 2009

Q. On fruits and vegetable my daughter has to make a graph of her findings and its her first time using a analog multimeter and we are confused

Amber O [last name deleted for privacy by Editor]
student - Brooklyn, New York


June 7, 2009

Q. I'm doing a science project for 6th grade and I wanna know if you know why my potato powered a clock longer than my lemon but the opposite for my friend?

Kimberly M [last name deleted for privacy by Editor]
Student - Beverly Hills, California


Pop Bottle Science

July 3, 2009

A. Hi, Amber. A graph is a mathematical language we use to illustrate and explain a relationship between two or more things. What exactly is it that you would like the graph to illustrate and explain? Your question is a bit like saying that your daughter has to write up her project in Spanish or French, so she is confused about what to write :-)  Start by expressing her findings in English, and I'll explain how to graph those findings. Good luck.

Hi, Kimberly. We've tried to explain several times why such a variation can exist, but it's probably just random depending on the particular nail, penny, the spacing between them, and particular sample of fruit and vegetable. But frankly you may be focusing your attention on a triviality. Do you think it is an important scientific fact whether a potato or lemon is better? If not, what is the heart of what you are learning -- that's what is important, so that's what you want to focus on. Best of luck.

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey


October 27, 2009

Q. Hi, I am Jeri and I am a tenth grader doing my science fair project also on using fruits to conduct electricity. My proposal paper is due soon but I am confused about something. My narrowing question or purpose of conducting my experiment is to find out if the different acidity levels in the various citrus fruits-lemon, orange, grapefruit, and lime effect the voltage of electricity in a circuit to light an LED light? But my question is, is experimenting on different fruits already the dependent variables? I would think they were all controlled variables and in order to make just one dependent variable in my experiment I would need to just conduct the experiment on lemons (controlled variable in the experiment) and then for the dependent variable in some way add more lemon juice to the lemon. By using a dependent variable I would get the results to truly answer my question. If so how would I be able to add more juice to my lemons? Using a syringe maybe? I appreciate any help and hope I have not worded the question funny, or in a complicated matter. Thanks.

jeri R [last name deleted for privacy by Editor]
student - Lutz, Florida


October 27, 2009

A. Hi, Jeri. Yes, you are complicating things and making it hard on yourself. You said the purpose of your experiment was to find out if different acidity levels effect the voltage. Stop there for a minute -- because your "purpose" has already identified the independent and dependent variable.

The acidity level is the independent variable that you will be varying and the voltage is the dependent variable that you will be measuring. The best way to get a range of acidity levels is probably to use a range of fruits. Good luck!

But while I can understand why 3rd graders are making fruit batteries, I am a bit disappointed that, 7 years deeper into their education, 10th graders are still playing with fruit instead of conducting more controlled experiments with real reagents :-(

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey


November 11, 2009

Q. Thanks in advance. My daughter is in 5th grade and doing a science project on the electric charge and resistance in fruits and veggies. The problem is, we were under the impression that all we needed for the experiment was the fruits & veggies and multimeter. We were able to measure the electric resistance; however, we didn't get a single reading for the electric charge....are we missing something? Please help!

Candis Jackson
parent of student - Chicago, Illinois


November 11, 2009

A. Hi, Candis. You can measure the resistance of a fruit or vegetable by merely setting the meter to resistance mode, poking the leads of the meter into the fruit, and reading the resistance of the fruit in Ohms. Note that the resistance will vary depending on how far apart the probes are; there will be less resistance when they are close together, and more resistance when they are at the far ends of the fruit.

'Charge' is a bad term. Please don't use it as it is both wrong and misleading. You want to measure voltage. To measure this, set the meter to voltage mode, and check a flashlight battery (D cell) or a AA or AAA battery. Your TV and VCR and DVD remote controls probably all have one. Such a battery will read about 1-1/2 volts if you have set the meter correctly.

Now put a galvanized nail, or something else that is zinc into the fruit, and a penny or something that is copper into the fruit. Measure the voltage from the nail to the penny and it should be in the neighborhood of 1 volt. Best of luck.

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey



November 12, 2009

Q. Can I hook up my whole garden in series to power my house?

What happens to someone that eats the vegetables after they are done conducting electricity?

Dan Pond
- Vancouver, BC, Canada


November 14, 2009

A. Yes, Dan, the lower forty alone should be enough to keep a nite light going. I wouldn't eat them because they'll have copper and zinc dissolved in them, and you might become the nite light :-)

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey



December 7, 2009

Q. Hey

I'm a class 12 student and I'm doing a project on fruit cells proving to be alternatives for Leclanche cell..
I've compared the emf of various fruit cells (the fruit juice acting as the electrolyte in this case) and successfully got fair enough values of the emf

My queries are
1. I need to know the pH of the different fruit juices I used which are
a)pineapple juice
b)mixed fruit juice
c)guava juice
d)litchi juice
e)orange juice
f)mango juice
(I couldn't find a pH meter and it is difficult to look for it in 2 days!)
( I tried the pH strip but all I got is a pink colour on it!
...In all the juices)

2. I also wasn't able to find out what major acids do these fruit juices contain and how much is the acid concentration in them
(The internet couldn't provide this information :-()

Please help me !

Sanskriti N [last name deleted for privacy by Editor]
- New Delhi, India


December 9, 2009

A. Hi, Sanskriti. The pH will probably range from about 3.0 to 5.9. I'm sure the teacher will provide fresh pH paper of the right range and show you how to use it rather than have you guess the pH of a "mixed fruit juice". Sorry, but that kind of guessing is not science.

The use of pH paper is widespread in science projects for grades K thru 5. I don't know what "class 12" equates to in our system, but any student pursuing science classes should know how to use it; wanting to take a pass on this at this point is inappropriate. Good luck!

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey


December 28, 2009

Q. Hi my name is Victoria. If I wanted to do the same experiment, what type of electrode should I use?

Victoria C [last name deleted for privacy by Editor]
6th grader - Brooklyn, New York


December 29, 2009

Q. Hi my name is judy. in the circuit, could you use a different fruit, for example a red delicious apple or the granny smith apple.

judy x [last name deleted for privacy by Editor]
4th grader - Boston, Massachusetts


December 29, 2009

A. Hi, Victoria. Many people recommend pennies and galvanized nails as the two electrodes.

Hi, Judy. Sure you can but ... it will be both difficult to conclusively prove that one type of apple is consistently "better" than the other, and fairly inconsequential when you have done so.

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey



December 30, 2009

Q. Hello, I'm Bailey and I am doing a science project on the electricity of fruits and vegetables. I am writing a research paper with back up information. I know that fruits do not produce electricity but they provide the ions. If the acid in citrus fruits provides ions, what provides the ions in cauliflower? I have little time so please answer fast.
P.S. I'm in 6th grade.

Thanks a bunch:-)

Bailey H [last name deleted for privacy by Editor]
student - OKC, Oklahoma


January 13, 2010

Q. Can you use other food like strawberries?

Lauren F [last name deleted for privacy by Editor]
- Crown point, Indiana


January 13, 2010

A. Hi, Lauren. My hypothesis would be that you can use other foods in general and strawberries in particular. Good luck.

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey



February 12, 2010

Q. My son is doing a science fair project to answer the question "how much electricity do different foods produce?". He used a galvanized zinc and a steel nail, inserted closely together into various fruits, vegetables (and peanut butter), then used a voltmeter to measure the volts produced.

He did 5 tests of each food and got average readings of 0.46 for an orange, 0.37 for for a potato, 0.2 for the peanut butter. These seem low compared to what I've read in the posts above. What do you think is going on? And is he asking the right question? He's in grade 6.

Ray LeBlanc
- Saint John, NB, Canada


February , 2010

A. Hi, Ray. I'll try to fully explain things at adult level and let you explain to him the portion he needs at his level --

You can take a small amount of salt, and stir & dissolve it into water, and the salt will stay dissolved. You can stop stirring, then try pouring it through a coffee filter, but the salt will stay dissolved (in ionic form, or as ions in the water).

But you can't keep dissolving salt into the water indefinitely; rather, the water has a solubility limit for salt. After that point, the extra salt will just settle out at the bottom when you stop stirring. Not all of the salt will settle out, only the amount which is beyond the solubility limit.

Similarly, metals will dissolve into water. Generally, if the water is neither acid or alkaline, very little will dissolve. As the liquid is more strongly alkaline or more strongly acidic, it will generally hold more metal dissolved into it. Once again, there will be a solubility limit.

So at a given acid level, you can dissolve so much copper into it or so much zinc or so much iron. So let's say you've put a piece of zinc into the acid and it has dissolved as much as it can and you take the piece of zinc out. Now you put a piece of copper into the acid, what will you see happen? Nothing.

Now take some fresh acid and put the piece of copper into it. After a while, take the copper out and put a piece of zinc in. What will you see happen? The zinc will become coated with copper. The zinc wants to dissolve more strongly than the copper wants to stay dissolved. For zinc to dissolve into this acid which is already saturated with copper requires that copper be driven out of solution.

We can say that zinc is more "active" or copper is more "noble" (iron is in between these two in activity by the way). But we can actually put numbers on how much more active zinc is. Google "electrochemical series". Compared to acid or hydrogen, copper is +.3419 volts, iron is -.037 volts, and zinc is -.7618 volts.

If you put a piece of copper and a piece of zinc into a perfect acid, you will therefore read a voltage of 1.1037 volts between them. If you put a piece of zinc and a piece of iron into a perfect acid, you will read .7248 volts between them. Between a piece of copper and a piece of iron you'll get .3789 volts.

Your son's numbers are lower than the other kids' because the potential between iron and zinc is less than between copper and zinc. They sound reasonable.

As for "asking the right questions", I'm sure you realize there is some "feel goodism" designed into this experiment, with natural fruits "creating electricity", and we don't want to completely torpedo that -- so I think he's doing fine.

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey


February 14, 2010

Q. I am in eighth grade and I am doing a science fair project about fruit producing electricity, but I do not have a zinc or copper electrode, but I do have a battery tester, will that help me at all with the experiment?

Dasser Silver
- miami beach, Florida


February 16, 2010

A. Hi, Dasser. View the youtube video which we link to at the top of this page. I know you can find a penny to use as the copper electrode, and your mom or dad probably has a galvanized nail to use as the zinc electrode. Good luck.

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey


March 10, 2010

! Hi.

Just wanted to say I found this site by accident. I think this it is superb and I only wish that the interwebs had been around thirty-five years ago when I was doing this type of stuff at school. I might have gotten somewhere instead of banging against a brick wall and failing the final exam.

Seriously good work, and thank you so much for enabling me to finally - at age 49! - understand the principles behind the lemon battery!

Darren Lynch
- Basingstoke, Hampshire, England


March 10, 2010

Hi, Darren. Yes, the internet can be a terrific learning tool when people like yourself want to learn. But it can also be a tool for those who don't want to learn, enabling them to find and cut & paste answers without having to do the hard work of thinking or trying to understand the question; that's what parents, teachers, and the rest of us try to guard against :-)

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey


March 14, 2010

Q. Hello I am doing this project on how to charge electronics with fruits and vegetables and I don't have a clue on the tools or items I need. also I don't even know how to start it or any steps.

Ramon J.
student - San Francisco, California


March 16, 2010

A. Hi, Ramon. Please try your best to express your question in terms of the information that people have generously taken the time to make available to you on this page already. I think the "lemon battery" video doesn't leave out too much. So maybe you could pose your question in terms of what you didn't understand in that video?

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey


September 23, 2010

Q. I'm currently writing some guides for people to try their own scientific experiments at home and school. What I am looking for is a source of very low voltage digital clock displays and other digital display units which can be provided with the kits for example the Lemon Battery. I can find them as parts in other items but I cannot find a supplier of the parts themselves. I only need a few to make the guides and provide the photos, does anyone know of a retailer in the UK who can provide what I need at affordable prices.

I need to show the electricity produces from these experiments in a clear to understand way and LED's are a bit plain I need to build something which the children can enjoy and a clock or text display would be far more interesting but I need the parts.

Alex Scargall
renewable energy education - Hull, Humberside, UK


Potato Clock

September 27, 2010

A. Hi, Alex.

It might be best to get a commercially available "potato clock" and see if there is a manufacturer name and model or part number on the display. With today's highly integrated electronics, I'd bet that any necessary drivers and decoders are built right into the display; I doubt that there are any other electronic parts required. It looks like they run off of two potatoes in series (probably about 2 volts for a device rated for 3). My own experience is that electronics are dirt cheap if you buy ten million but unfortunately very hard to find inexpensively if you only need a few :-(  Good luck.

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey


October 6, 2010

Q. I actually having an experiment which is producing electricity from tomato and it was successful but the problem is I didn't know the acids that are present in tomato, can you please give me the answer. Thank you and god bless.

Jun Carlo L [last name deleted for privacy by Editor]
student - Surigao del sur, Philippines


October 10, 2010

A. Hi, Jun. There are 10 acids in tomatoes: acetic, lactic, fumaric, malic, pyrrolidone carboxylic, citric, phosphoric, umbiolic, hydrochloric, sulfuric, and galacturonic. Oops, I listed eleven instead of ten; I guess I just sat here and made one of them up :-)
This illustrates the fact that a public internet forum may steer you in the right direction, and it may give you some good answers, but they probably will be mixed in with bad answers. And the question becomes how to judge whether the information is trustable or not? What do you suppose this project is supposed to be teaching you about how to do research? If you look up those 11 acids there will be one that nobody ever heard of because there is no such thing :-)

Good luck, and Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey


January 10, 2011

Q. I would like to create enough electrical power to power a cell phone for a 1 min phone call. If I connect the fruit in series with a copper and zinc nail can I increase the voltage of the fruit battery?

Melanie W [last name deleted for privacy by Editor]
5th grade student- with parent permission - Beaumont, California, USA


January 12, 2011

A. Yes, Melanie, you can. If one fruit battery gives you 1.0 volts, then 5 in series would give you 5 volts. I'm not sure what voltage your phone needs, but that's how you figure it, and 5 volts may be enough -- but you probably don't have enough current without a bunch of sets of 5 wired in parallel.

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey


February 16, 2011

Q. I need to conduct electricity using a lemon for a science fair. What can I use instead of zinc. I am a 7 grader. Any help would be highly appreciated.

Akansh B
student - Roorkee, India


February 16, 2011

A. Hi, Akansh. You can use any two dissimilar metals you wish. Silver and steel for example. The voltage that the battery generates will depend on which two metals you pick and how far away from each other they are on a chart called "the galvanic series". But I don't understand why you don't want to use zinc when it is cheap, readily available, and produces good voltage. Good luck.

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey


March 12, 2011

Q. Mr. Trevor Crichton made a comment about using a potato to power a clock and said that when the potato shrivels up it would stop working. My question is, "What if the potato is planted with the electrodes still in would it continue to make electricity?"

Bill Smith
- Pikeville Kentucky USA


March 14, 2011

A. Hi, Bill.

A potato doesn't really "make electricity" in any different sense than a glass of saltwater makes electricity. The salts in the potato are simply conductive like saltwater. As long as the potato doesn't dry up, so there is a wet conductive path between electrodes of two different metals, electricity should continue to flow. But as it flows, one electrode becomes slowly coated with whatever metal the other electrode is made of. And once it's completely coated, there's no difference in the surfaces anymore, and the battery dies.

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey


May 22, 2011

! Thank you so much for all of the information on this website! It is really helpful! I'm also doing a science project on conducting electricity with fruit and I'm going to test the pH to see if that affects it. My only question is why would the acidity make a difference. Thanks again!

Noa
9th Grade

Noa E. [last name deleted for privacy by Editor]
- Pittsburgh, Pennsylvania, USA


September 15, 2011

Q. I'm in 8th grade and I'm doing a science project and I need to know who discovered that electricity can travel through a fruit. Thanks.

Tanner L [last name deleted for privacy by Editor]
student - Chula Vista, California


September 16, 2011

A. Hi, Tanner.

Let me ask you a question first...

Who discovered that 12345 plus 56789 plus 34556 equals 103,690? It's possible that nobody ever added those three numbers to together, and that you & I are the first to ever discover it! . . . still, it doesn't impress us much because it's not so much a real "discovery" as it is just combining some very simple known facts to arrive at a reasonable conclusion.

Similarly, if we already know that electricity will flow through conductive liquids, and we already know that fruits contain conductive liquids, it wasn't really much of a discovery. But at some point in your science education you might decide to research who first discovered that electricity will flow through conductive liquids and postulated how. Good luck on your project!

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey


October 8, 2011

Q. Hi, I'm doing the fruit and vegetable battery project and I am using a lot of fruit. I am using a coin for copper and a dime or nail for zinc. My light bulb is 6 volts and is really, really, small. There is no negative or positive thing for it so I don't know how to connect it. I really need some help. I have the alligator clips and some red wires.

Maham G. [last name deleted for privacy by Editor]
- Houston, Texas, U.S.A.


January 17, 2012

Q. Hi,

My name is Annette. I am an 8th grader in middle school, and I am working on a science project called the "Discovery Project". Basically, you come up with a standard experiment that follows the scientific method that you come up by yourself and perform on your own. Students need to find an expert in their field to help them with their field to make sure that the experiment will work, and that the experiment will work smoothly, provide guidance, and explain things that did NOT work. My scientific question is "How does the type of fruit affect the amount of voltage it can produce? My experiment is based on this experiment here: www.how-things-work-science-projects.com/lemon-battery.html#lemon_battery. I need an expert, so if any of you would be willing to help, thank you very much! I will need an email address back somehow.

Thank you! Reply soon, please.
Annette.

Annette G. [last name deleted for privacy by Editor]
Student - Issaquah, Washington

----
Ed. note: Asking strangers on the internet to contact you can be dangerous. Annette. Please give us your teacher's e-mail address or your parent's e-mail address and we can post that.


April 29, 2012

Q. The metal used for electrodes must be different? Does the battery work if the same metal is used for both electrodes?

ruby l [last name deleted for privacy by Editor]
- england


May 9, 2012

A. Hi Ruby. No, it doesn't work if the same metal is used for both electrodes.

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey


April 24, 2013

Q. If I use stainless steel as electrodes, will it still conduct electricity?
Does juice play any role in production of electricity?
What is electrical conductivity?
Is this have any relation with juice conductivity?

Yatharath [last name deleted for privacy by Editor]
- Ludhiana, Punjab, India


April 24, 2013

A. Hi Yatharath. We weren't in the classroom with you and don't know exactly what you are questioning. So you need to take the time to very clearly explain what you understand and what you do not yet understand -- because we will only further confuse you by attempting to answer vague questions :-)
1. Do you very very clearly understand exactly what you mean by "conduct electricity"? Because the answer is: certainly stainless steel electrodes will "conduct electricity". But if you don't very clearly understand your question you will probably leap to all the wrong conclusions :-(
2. Does juice play any role? Of course it does, but juice would never be used in commercial production of electricity.
3. Electrical conductivity is a fairly specific term meaning the inverse of electrical resistivity. But that probably doesn't help you.
4. Juice "conductivity" is the same thing.

Please please please take the time to clearly phrase your questions in terms of words you already clearly understand, and then I am sure I can help you. But if you simply mouth terms and phrases that you don't really understand I will just be leading you deeper into confusion :-(

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey



March 11, 2014

Q. Is there possibility for a cabbage to produce electricity?

Kioria Njoroge
student - Nairobi,Kenya


March 2014

A. Hi cousin Kioria. I don't think it's helpful to a person's education to answer a question if the person asking the question does not understand what they are asking. If you can phrase your question in such a way as to demonstrate that you very clearly understand your own question, I will be happy to try to answer it. But if you don't understand the question, you must ask your teacher to carefully explain the question rather than attempting to provide him/her an answer to a question you don't understand. Good luck.

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey



November 16, 2014

Q. Hi, I would like to ask to how to find the resistance offered by fruits using potentiometer? Please reply at earliest.

Nehal Ambat
- new delhi,india


November 2014

A. Hi Nehal. Are you sure that you know what you mean by resistance? And what a potentiometer is? And that you truly visualize the situation described by your question? If you don't, you must explain to the teacher that you don't understand the question.

wikipedia
1. Potentiometer

2. Potentiometer (measuring instrument)

What you want to do is not impossible, but I'm thinking it would be a bit silly, with the fruit hooked up as RL in the graphic of the first Wikipedia article.

Actually, I think you've misworded the question, and I suspect that after you talk to the teacher you will want to look at "unknown voltage" in the graphic of the second Wikipedia article instead. Best of luck.

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey


January 18, 2015

Q. Can you detect electric charge in fruits and vegetables? If yes, which vegetable or fruit has the highest charge? I am a 7th grader and I need help with this ASAP please

Tiana C [last name deleted for privacy by Editor]
- Toronto,Ontario,Canada


A. Hi Tiana. Fruits and vegetables do not have "electric charge". But their juices will conduct electricity in the same way as water, especially salt water, does.

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey



January 26, 2015

Q. Good day sir,
I conducted an experiment at school where I used various food extracts as electrolytes (potato juice, lemon juice, lentil water, rice water, etc.)
I put these in a beaker and used TWO copper electrodes and connected a voltmeter with it. AND I got varying EMFs of the cell for different extracts. Can you please explain the logic behind this?
Thank you,

Vidhi G [last name deleted for privacy by Editor]
Student - Delhi, India


January 2015

A. Hi Vidhi. Sorry, no, that's not explicable in my experience. But if you provide facts & figures, someone may be able to deduce a pattern from them.

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey


February 2, 2015

A. Might it be that the different solutions tested had varying conductivities, and the resistance between the electrodes became a limiting factor? Although, with both electrodes of the same metal, there should be no current flow at all anyway.

Ray Kremer
Stellar Solutions, Inc.

McHenry, Illinois



January 29, 2015

Q. Hi there,
I am doing an investigation on which fruits would work best to generate the highest voltage and I was wondering just how voltage is generated within a fruit cell, if the fruit's pH is a factor to consider or if it is a chemical reaction with copper and zinc electrodes?

Robin M [last name deleted for privacy by Editor]
- likoni, mombasa, kenya


February 2015

Hi Robin. If you have the patience to slowly think this through, I think you can largely understand it even though parts may be beyond your experience and mine...

The most basic thing that happens is that if you put a metal rod into a mild acid like a fruit juice, a very small amount of the metal will dissolve into the acid, similar to the way that a certain amount of salt or sugar will dissolve into water. That is, a few of the metal atoms on the surface separate into positively charged ions of the metal that go into solution, and negatively charged electrons that accumulate on the rod. A balance is achieved whereby these positively charged dissolved ions are constantly drawn back to the negatively charged electrons on the metal, but as they reach it, another metal atom dissolves to keep the balance.

If you put rods of two different metals, say zinc and copper, into the acid, a small amount of zinc ions will go into solution and a small amount of copper ions will go into solution in the same way. But if you now connect a wire between the two rods, so that electrons can flow from one rod to another, things change because the zinc ions are stronger at wanting to go into solution, and the copper is stronger at grabbing the electrons and coming out of solution. So, a zinc ion will go into solution and a copper ion will deposit on the zinc rod by grabbing an electron and becoming a copper atom again. As this occurs the copper rod will dissolve more atoms into positively charged ions and negatively charged electrons, depositing onto the zinc rod, and force a zinc atom to ionize into solution. But since electrons are now free to travel from one rod to the other via the wire, they will flow from the copper rod to the zinc rod, and as they do, since negative charges are no longer building on the copper rod, it can continue to dissolve, and since electrons are now building on the zinc rod, they can neutralize copper ions into copper metal deposits. Eventually the zinc rod becomes completely covered with copper and everything stops.

Regards,

Ted Mooney, finishing.com
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Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey


February 2, 2015

Q. I was wondering, out of these three items, which is the best producer of electricity? The items I have are a potato, a lemon, and an orange.
Sincerely, Cameron

P.S. i need a response ASAP because this for my science fair project

Cameron C [last name deleted for privacy by Editor]
- madison heights, virginia


February 2015

Hi Cameron. Any of the three will be fine. But your wording "producer of electricity" is vague and misleading. These fruits & vegetables do not produce electricity; they are simply conductive (which means that atoms of metal can dissolve into them). Ketchup or vinegar will do the same.

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey



March 2, 2015

Q. I am 9 years old and in the fourth grade. I read different sites and saw the experiment work at my cousin's science fair, yet when I tried to create a similar experiment I was unsuccessful. What went wrong? I used a lemon with a copper penny and zinc washer and got no reading from multimeter, I used a different lemon with 15 gauge copper wire and zinc nail still no reading and the third lemon I used a paper clip and 18 gauge coper wire and again no reading. (even tried rolling lemon before experiment with lemon #2). My Digital Multimeter works because it read AA battery at 3.62 mhz. I'm frustrated -- what am I doing wrong? Thanks you for your help.

lemon battery

Adrian Alvarado
- San Pedro, California United States


February 2015

A. Hi Adrian. I think your multimeter is set on the wrong scale. It should be set for DC volts, probably 0-10 VDC or something like that. Then your AA battery will read 1.5 Volts, and your copper coin to zinc nail will read about 1.0 Volts.

3.62 MHz means 3,620 cycles per second on and off, and has nothing to do with AA batteries or lemon / potato batteries. Good luck.

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey



May 11, 2015

Q. Hi:)

I did an experiment and found that limes, apples, grapefruit, mangoes and plums all conducted energy better than lemons and oranges, which I expected would conduct more since lemons are what everyone uses for their projects. I've done some research but everyone seems to have different opinions on the topic. What do you think makes some fruits conduct more energy than others?

Thanks a lot

Sophia Allan
- nyc, New York, U.S.A


May 2015

thumbs up signHi Sophia. You didn't mention what grade you are in, but you need to be rather careful with terminology like "conducted energy better" and "conduct more energy". You are expressing yourself rather vaguely about some observations you made. Trying to answer "why" something happens that you haven't clearly enunciated, can confuse and mislead you :-)

The role of the fruit juice in this case is probably mostly to provide a conductive electrolyte. That leads me to a thought: Have you ever eaten orange segments? Suppose you've peeled an orange, and you've eaten most of it, and now you have two segments left. Do you think you'll get the same or different results if you stick both of your probes into the same segment, versus sticking one probe into one segment and one into the other, being careful not to puncture the membranes separating the two segments?

Regards,

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Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey
Striving to live "Aloha"


May 29, 2015

Q. Hi there. Regarding that project I had a similar one. Just that am in advanced level. We planned to charge a phone using the fruits. Is it possible? Need advice on how to do it.

Steve Paul
- New-York. Usa


A. Hi Steve. Almost anything is possible, surely including charging a phone using fruit batteries...

What voltage does a phone charger for the phone in question provide? What amperage does it provide? Hint: my questions provide the advice you asked for on how to go about it.

Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey
Striving to live "Aloha"



July 7, 2015

Q. Hi,

My son (12) is doing a year 8 (not sure what that is in other countries) holiday science project. We are running a small digital clock from various produce and liquid, for example a Kumara (sweet potato), bread, water, etc. using copper and zinc electrodes attached to wires from clock to two of each item and a white wire with a copper and zinc electrode running to the opposite. One of the things he used which we found that did not run the clock but cannot find a reason why from Google is butter. Are you able to give us the reason why please? I was wondering if butter in fact acted as an insulator rather than a conductor. Another one we found was salt (two small cups). Thanks,

Sherryn Quate
- New Zealand


July 2015

A. Hi Sherryn. You're halfway there in finding that some things will support this battery action if the probes are inserted into them and some will not. But the issue or principal that your son should be getting is what is actually happening that accounts for the electricity flowing ...

If a single metal electrode is placed into acid it will slightly dissolve into the acid, much like salt or sugar will dissolve into water to a given equilibrium point (if you add too much salt or sugar it just settles on the bottom as a syrup). As the metal slightly dissolves into positively charged ions in the solution (atoms less one or more electrons) this leaves excess electrons on the metal electrode, and they attract ions back and reform metal, and this is what comprises the "equilibrium".

But if you put both copper and zinc rods into the same solution, when the dissolved copper ions (atoms of copper less two of their electrons) happen to reach the zinc electrode, they will steal two electrons from the zinc metal and become copper atoms again, plated out onto the surface of the zinc. Why copper has this stronger thirst/affinity for those electrons than zinc may be beyond your son's level, but the principal of what is happening probably isn't.

As mentioned, when the copper atom dissolved, it left those two electrons on the copper electrode, and they will now flow through the wiring to get over to the zinc electrode to balance things out. This flow of electrons through the wiring is what we call electricity. The reaction will continue until the zinc is completely covered with copper and the surface of the two electrodes is the same metal, so nothing further can happen and the "battery" is dead.

Butter is oil rather than water, and will not support the dissolving of metal into ions. So it's not that it's an insulator, it's that metal can't ionize into it. Similarly, dry salt crystals cannot support metal ionizing into it. Good luck.

Regards,

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Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey
Striving to live "Aloha"



October 15, 2015

Q. Actually, I have four questions:
1). What does zinc look like?
2). Do I need a high watt battery to power this circuit, and how many do I need
3). Can I also use an unripe orange?
4). And is it a 60 watt bulb light I will use to the circuit or just a smaller one?

Ignatius Princess
- Lagos,Nigeria


October 2015

A. Hi Ignatius.

1. Zinc is gray and metallic looking. Galvanized nails, galvanized roofs, and boat anodes all have a zinc surface.
2. I don't know what circuit you are speaking of, but I have been speaking of a "fruit powered battery", where a piece of copper and a piece of zinc stuck into the fruit comprise the battery.
3. Yes, you can use an unripe orange.
4. Your circuit will be unable to light even the tiniest penlight flashlight bulb. You would probably need a dozen fruit batteries wires in parallel to light that penlight battery, or a few to light even a small LED per the youtube video we referenced.

Luck & Regards,

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Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey
Striving to live "Aloha"



January 4, 2016

Q. How does the amount of acidity in a fruit affect the amount of electricity it can produce?

Iliyan Kajani
- Atlanta, Georgia, U.S.A.


January 2016

A. Hi Iliyan. That question was answered in detail several times on this page already. Please try to read and understand the explanations, then to re-phrase your question so we can resolve any remaining uncertainty you have.

Also, try to think carefully what the word "amount" means to you because I can think of at least two different meanings (alkalinity and pH) related to "the amount of acidity", and many meanings (voltage, current, power, energy) regarding electricity. Good luck.

Regards,

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Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey
Striving to live "Aloha"



January 12, 2016

My 5th grade son is conducting an experiment where he wants to find out if changing the state of the potato will influence its electrical output.

I want to make sure that he is conducting the experiment correctly -- Would appreciate your help.

He tested a potato battery made up of 3 yukon gold potatoes cut in halves and was able to light a 2 Volt small LED light.

He now wants to boil 3 potatoes and test these to see if the voltage is higher when the potato is boiled,

He then wants to place 3 potatoes in salt water (1 tablespoon of salt dissolved in 1 cup of water) and test the voltage

Finally he will place the 3 potatoes (cut in half) on salt for a day and test the voltage.

HE is hoping that by changing the state of the electrodes he will produce a larger flow path and therefore allow more electrical output to generate when using the potato.

His hypothesis is that the potatoes placed directly on salt will give the most power as it will increase the electrodes the most.

Is he on the right path? Is he stating his question correctly?

Thank you for any help with this

Paola Preble
- Fernandina Beach, Florida, USA


A. Hi Paola. The basic problem is that it's the two metals which generate the voltage, not the potato. All the potato does is provide a conductive liquid path. But I would guess that, yes, if you use a strong salt solution, with the metals placed close together, the resistance of the circuit is lower and you should be able to get more current to flow, and the LED to glow more brightly. With more current flowing, the battery will go dead sooner though.

Regards,

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Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey
Striving to live "Aloha"



February 10, 2016

Q. Hello, I'm creating electricity in my 7th period class. We are trying to create electricity from an apple, orange, banana, and a potato. I was wondering if you can actually do this and does it actually light up an LED light?

emili quam
- devils lake North Dakota


February 2016

A. Hi Emili. Please look at the youtube video of the lemon battery on this page. The person making the video found that he had to wire 4 lemon batteries in series to light a small LED.

Regards,

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Ted Mooney, P.E. RET
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March 6, 2016

Q. Hello!!
So my 6 year old is participating in his first Science fair! We both decided to do a Digital Fruit Clock! (He got a "Lemon Clock" kit for Xmas complete with two copper and Zinc rods, red wire, Black Wire, white wire, and a digital clock) We started to do experimenting on fruits and NON fruits. The clock worked with an Avocado, Lemon, Banana, and a pear. The Clock did NOT work with Peanut butter, Butter, and a chocolate chip cookie. We were trying to find things it WOULD NOT work with and found that water works, milk works even BREAD! Why Bread? In conclusion we need to figure out WHY it works for fruit as opposed to butter, Chocolate chip cookie, and peanut butter. What is it that the Milk, water, bread and fruit have in common that it would make the clock work but NOT the butter, Peanut butter, and cookie... PLEASE HELP!!!

Kimberly Long
- Seattle, Washington


March 2016

A. Hi Kimberly. I hope you tried these materials repeatedly because it would be foolish for him to carefully explain why something is true if it's not true :-)

But assuming the results are repeatable, it means some of the materials conduct sufficient electricity to run the clock (it probably takes very very little) and some do not. Anything with a little water in it probably works, and things that are dry, or based on oil rather than water, do not. If you happen to have an electrical meter you could measure the resistance of each of these objects.

Regards,

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Ted Mooney, P.E. RET
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March 15, 2016

Q. Hi, I have a science fair project at school. And I chose "Which combination of vegetable and fruit has the highest voltage?" And it's like a different thing to do here.

Brokson Kevin
- Mandalay, Myanmar


A. Hi Brokson. Sorry, but it's not the fruit or vegetable which you choose that determines the voltage, but the two metals. I'm not happy to have to tell you that, but it is what it is :-)

Regards,

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Ted Mooney, P.E. RET
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April 5, 2016

Q. Hi, Please help me a year 6 student get an answer for why energy is increased in voltage if more fruits are used?

khushi bajaria
- mombasa,ganjoni,kenya.


April 2016

A. Hello Kushi. Copper has a much stronger pull on electrons than zinc has: about 1.0 volts worth. So if you put a piece of copper and a piece of zinc into a fruit, a meter would record about 1.0 volts between them as some of the electrons in the zinc metal are pulled through you wiring and over to the copper metal. If you put two such batteries in series (connecting the positive end of one to the negative end of the other, much as you stack 1-1/2 volt batteries in various electronic devices, you would get about 2.0 volts between them. If you stack 4 of these 1.0 volt batteries you get about 4.0 volts.

Regards,

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Ted Mooney, P.E. RET
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Pine Beach, New Jersey
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April 14, 2016

Q. Can you make a banana battery?

Sharnujan Sivanethura
- Toronto, Ontario, Canada


May 31, 2016

A. Using any fruit with a high acid content and 2 Dissimilar metals will generate electric current. Peanut butter is not terribly acidic so you won't get much if any electricity. You can build a simple "Voltaic Pile" (named after Alessandro Volta. Also where we derive the name "Volt" from). All you need are some silver coins and copper coins, some vinegar and blotting paper. Simply cut some squares of the blotting paper slightly larger than the coins and moisten them with the vinegar. Place a copper coin on the table, put a piece of the blotting paper on top then put a silver coin on top of that. Keep repeating the process making sure to alternate the coins. When you have your desired "stack height", touch your multimeter probes on the top and bottom coins and be amazed! (hopefully)

Chuck, Melbourne Australia

Chuck Solide
Tube Bending, Powder coating and Metal Fabrication - Thomastown, Victoria, Australia


thumbs up sign It's okay to build the stack high enough that you're amazed; but don't build it so high that you're shocked :-)

Regards,

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Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey
Striving to live "Aloha"



July 3, 2016

Q. Hello Ted,
I've seen many reports online of a boiled potato producing 10x more electricity when used in these typical zinc-copper "fruit batteries" than a raw potato, but these reports seem to all be reiterations of the same news report from 2010 about the Hebrew University of Jerusalem. I can't find anyone else actually doing an experiment using a raw and a boiled potato and documenting it online (outside of the recent question this year from Paola here on this thread, but her child's results weren't posted). Here is an example of this finding: http://www.smithsonianmag.com/innovation/a-potato-battery-can-light-up-a-room-for-over-a-month-180948260

Based on all of the wonderful information you've provided here, I have my doubts that this will make a difference -- certainly that much of one, especially since you've pointed out that there is a maximum which can be produced using zinc and copper as electrodes. Even in ideal conditions. Unfortunately, I don't have time or resources to create the experiment myself, as I'm just doing research for a paper (we don't even have pennies in this country).

Can you please tell me if you think it's possible to produce exponentially more voltage in the potato battery setup by using a boiled one? How can that texture make a difference? Cheers in advance!

Jemima Brown
- Katoomba, NSW, Australia



We'd love to give credit for this graphic explaining Ohm's Law (A = V / Ω) but we see it on many websites with no hint of whose work it actually was :-( 26203-2
July 2016

Hello Jemima. The voltage of the battery will remain unchanged because it is a function of the two metals employed (copper and zinc). But the maximum current that metal plates of a given size can produce is increased because the boiled potato is a better conductor. The practical implication is that more power can be generated in a given space, i.e., it's a more practical packaging method/design for the battery.

The biggest problem is that this corrosion of zinc and copper isn't really "free" energy because it costs more energy to make zinc and copper from ore, i.e., to un-corrode them, than you can get from corroding them like this. Batteries can be a convenient storage device for energy, but they don't actually produce energy, they just release a portion of the energy that was stored in them.

Regards,

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Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey
Striving to live "Aloha"


July 3, 2016

thumbs up signHi -- just a quick note to thank you so much for taking the time to provide such a thoughtful and articulate answer to my boiled potato question, and so quickly! It's really wonderful that you've been keeping this thread and information going for so long. Cheers from Oz!

Jemima Brown [returning]
- Katoomba, NSW Australia



August 9, 2016

Q. I'm doing a project for the equivalent of a science fair. I'm thinking about doing something with fruit conductivity, but one question has piqued my interest. Why must zinc and copper be used to make a fruit part of an electrical circuit?

thanks in advance,
Edward, a year seven sudent.

Edward Meade
- Sydney, New South Wales, Australia


A. Hi Edward. For reasons that are beyond grade 7 level and maybe my level, zinc attracts electrons more strongly than copper does. So if you put the two metals into a conductive solution but not touching each other, and you attach a wire between them, electrons will flow through the wire from the copper to the zinc. As this happens, the copper atoms on the surface of the copper, having lost their electrons, do not remain a metallic solid, but dissolve as positively charged copper ions into the solution (much like salt or sugar dissolve into water). The positively charged copper ions migrate through the solution until they reach the zinc electrode and are able to regain their electrons and come out of solution, as copper plates onto the zinc electrode. The process of electrons flowing through the wire from the copper to the zinc, and copper ions dissolving into solution and traveling to the zinc electrode continues until the zinc is completely covered with copper and the process dies out.

You do not have to use zinc and copper, you can use any two metals as long as one has a stronger attraction for electrons than the other. You may have heard of carbon-zinc batteries, nickel-cadmium batteries, etc. But zinc and copper are readily available, relatively cheap, and the difference in attraction of electrons is large, so they generate a good voltage (about 1.1 volts).

pic of Ted Mooney
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey
Striving to live "Aloha"


January 5, 2017

Q. Hey, How can i measure the moisture content of a fruit by passing an electric current through it? And how much current should be applied.

Emmanuel Mwadime
- manila, philippines


January 2017

A. Hey, Emmanuel, I don't think you can. What leads you to believe that it can be done?

Regards,

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Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey
Striving to live "Aloha"


January 16, 2017

And what unit of measure are you looking for "moisture content" in?

Electrical conductivity in this context requires there to be liquid, and for that liquid to have ions in it. The liquid is usually taken as a given, so conductivity is often used as a measure of how many ions there are. If the liquid dries up and the ions turn into solid salt, it would pretty much lose conductivity, but it's doubtful you would need to measure the current to be able to notice that.

Ray Kremer
Stellar Solutions, Inc.
McHenry, Illinois


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