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What is a Lemon Battery?

A lemon.
A lemon battery is a classic science experiment.
A copper coin or wire is needed to make a lemon battery.
Galvanized nails, which have a protective zinc coating, can be used to make a lemon battery.
Article Details
  • Originally Written By: Michael Pollick
  • Revised By: G. Wiesen
  • Edited By: L. S. Wynn
  • Last Modified Date: 06 September 2014
  • Copyright Protected:
    2003-2014
    Conjecture Corporation
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A lemon battery is a classic science experiment used to demonstrate the basics of a chemical battery system. To conduct this experiment, a scientist needs one very juicy lemon, a galvanized or zinc-coated steel nail, and a clean copper coin or section of household copper wiring. The scientist making the battery also needs a wire with alligator clips at each end and a sensitive voltmeter. Voltmeters can usually be found in the electrical supply section of a hardware store, electronic hobby store, or home improvement center. Small Light-Emitting Diodes (LEDs) and other electrical devices can also be used to test a lemon battery, though this typically requires additional lemons.

How it Works

A lemon battery relies on electrons and a chemical reaction that takes place when metals are introduced to an acidic mixture. The lemon contains a significant amount of acidic juice, which in scientific terminology is an "electrolyte." Acid in an electrolyte helps break down the atomic structure of metals, like copper and zinc, causing the release of individual electrons. When a scientist creates a circuit, by connecting the two metals with a conductor, the electrons flow through it as an electrical charge, which can be detected on a voltmeter or other device.

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Making the Battery

First, the scientist creating a lemon battery should carefully insert the copper coin or household copper wiring into one end of the lemon, then insert the galvanized nail into the opposite end. It is important for the scientist doing this to make sure the two metals do not make contact with each other. This would close the circuit, and holding the metals while they touch could result in a mild electric shock.

Creating the Charge

The nail and the coin have now become electrodes. Both copper and zinc allow electrons to flow through them, which means they are considered excellent conductors of electricity. The copper coin or wire is considered a positive (+) electrode, while the zinc-coated nail is a negative (-) electrode.

Free-flowing electrons found in the lemon-juice electrolyte naturally want to move from the negative to the positive electrodes. How fast these electrons flow is measured as amperage. The voltmeter picks up on this by displaying voltage, which indicates the "electrical pressure" working within the circuit.

Measuring Voltage

A single lemon battery does not produce a significant amount of voltage, but a sensitive voltmeter should detect some electrical output. The scientist should connect the positive clip of a wire, the end with a red casing, to the copper coin or wire; and the negative clip, the end with a black casing, to the galvanized nail. A digital readout or analog dial on the voltmeter should show a small voltage number, usually less than one-tenth of a volt. This is not typically enough to run a digital clock or power a light bulb, but it does demonstrate that an electrical current has been generated through a chemical reaction within the lemon battery.

Increasing the Charge

While a single-cell lemon battery is functional, it provides little meaningful electrical charge. Additional voltage can be provided by increasing the number of cells, or lemons, within the battery. A series of lemons can function together as a single battery through additional wires attached from the positive electrode, copper part, of one lemon to the negative end, zinc nail, of another.

About four lemons connected in series in this way should provide enough power to light a small LED. The scientist should connect the negative lead from one end lemon to the LED wire closest to a flattened area of the casing. He or she can then connect a positive lead, from the other end lemon, to the other wire. A dim but noticeable glow should light in the center of the LED; additional lemons or cells can be added to the battery for greater charge and an even brighter glow.

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Discuss this Article

anon949730
Post 43

Heat it. It worked for me.

anon257186
Post 39

What is the purpose of the acid in the lemon for this experiment?

anon162325
Post 37

the chemical reaction between the lemon the copper and iron nail caused the flow of electricity causing the LED to glow dimly. what is this process called? Our science teacher told us that it is oxidation. Is he correct?

anon129284
Post 32

I need to know if you do this but don't have a voltemeter. so if you can just touch the wires together to make a shock? Please answer. Thank you.

anon121338
Post 31

This really helped me figure out what happened with my project and why it worked. Thanks!

anon85570
Post 30

This site is great if you're looking for the particle side of the explanation!

anon82086
Post 29

Copper and zinc work well because they are far apart on the reactivity series of metals. The further apart, the better the reaction.

anon80475
Post 28

wow this helped me a lot! great site! very specific and overall great!

anon78440
Post 27

great site!

anon78439
Post 26

Actually, any two metals will work. And also, you can increase the voltage of one lemon, by replacing the penny.

You simply take copper wire (20 cm) and wrap three out of four around your finger, creating a loop, and insert it in the penny's place. This will give you a higher voltage because it gives you ample surface area. I think it doubles (nearly) your result with the penny!

Great site by the way! Helps a lot!

anon76995
Post 24

It really helped me in my report.

anon70443
Post 23

This was very helpful. I had to write a paper about how a lemon battery works.

anon68937
Post 22

Me too on my science fair worksheet and I got a good grade. thank you.

anon65539
Post 21

We just set up a two cell lemon battery which drives a small digital clock quite beautifully. The battery generates 1.5 volts, but its current output is quite limited, not enough to drive a larger electro-mechanical clock which requires an AA battery. Thought of putting three batteries in parallel. May yet try that.

anon64973
Post 20

thanks stacks - very helpful. really appreciate you scientists trying to help schoolkids enjoy the subject. Thanks

anon62240
Post 18

Is it possible to do this experiment without a voltmeter? Thanks.

anon49370
Post 16

Where can I purchase a tiny digital clock for this experiment?

anon48178
Post 15

i need to know all these stuff you asked too, for my project.

anon28799
Post 13

We made our lemon battery using a zinc coated wood screw and a copper penny. We produced 7 volts by wiring 12 lemons in a series circuit. This produced enough amperage to make a smoke alarm horn wired directly to make an audible horn. This is much better than an LED which you cannot see in a well lit exhibit room. The horn was a much better demonstration. We used a 10" cake pan to neatly arrange 12 small lemons. And one outside the pan for the initial demonstration

Pinkgrape
Post 12

i recently did the lemon battery for a science fair project, and this article provided me with some great info for the research paper

anon24602
Post 11

i tried this before, its fun and really cool.

anon23362
Post 10

can you charge an ipod with an ipod charger with the lemon battery???

pinkpony500
Post 9

What is the purpose of the lemon juice in this experiment? What exactly would it represent in a battery?

anon12731
Post 8

You don't need any special wire. Just copper and steel.

anon10716
Post 7

I need to know why copper and zinc are best to make a lemon battery.

anon9194
Post 6

Can You Use a Steel Wire? I heard You Have to Use A Zinc or Galvanized Wire or nail. Can You Use Steel Wire Or Steel Nail??????

anon7821
Post 4

Thank you to the makers of this site. This information is very useful.

anon4776
Post 3

I would like to add that the "flow" of electrons is Amperage and the "Pressure" is Voltage. I want to thank you for this site and trying to instill a love of science into our children of this world.

anon1627
Post 2

i would like to know chemically, how increase in lemon juice will increase the voltage.

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