Did you know that you can power a lightbulb with just a potato or two? The chemical energy between the two metals is converted to electrical energy and creates a circuit with the help of the potato! This creates a small electrical charge that can be used to turn on a light.
This tutorial is a great example of how energy comes in many forms and how products use that energy in order to do work. The potato battery converts energy from chemical to electrical in order to allow the light bulb to work (benchmarks C and D).
Follow Faith Davis, Cheyenne Balzer, and Spencer White through this tutorial in order to make a battery out of a potato, and hopefully learn something about the use of energy and the technologies that use it!
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Step 1: Gather Materials
- 2 Potatoes (can be done with more if you want more power)
- 2 pennies
- 2 zinc-plated nails/screws (most screws are already zinc plated)
- 3 pieces of copper wire
- a small LED lightbulb or a voltmeter
Step 2: Strip Copper Wiring to Fit Penny
You need to make sure that you are stripping enough wire to wrap securely around the penny.
Step 3: Cut a Slit Into Each Potato
Each slit should be able to fit a penny, but it doesn't need to be exact because it can always be adjusted later!
Step 4: Wrap Penny With Wire and Put It in the Potato
The wire-wrapped-penny should fit snuggly into the slit you made earlier. This may take some adjusting and a little force to get the penny in right.
Step 5: Cut the Other End of the Copper Wire
On the side that the penny is not attached to, trim the wire to the length you want between the other potato plus an inch or two.
Step 6: Insert the Zinc-plated Screw Into the Potato
You want to leave enough of the screw out for the other end of the copper wire to wrap around, but still have the screw snug in the potato. Be sure that the screw doesn't go all the way through your potato! This step will take some force, and it's easier if you twist it in instead of trying to jam the screw in there.
Step 7: Wrap the Other End of the Copper Wire Around the Screw
Connect the two potatoes together with the wire going from the penny to the screw.
Step 8: Repeat Steps 2 - 4
Cut a new slit for a penny into the second potato that already has a screw and fit the new wire wrapped penny into that potato.
Tip: we cut all our wires to be around the same length overall to make things easier later on.
Step 9: Repeat Steps 6 - 7
Insert a screw to the potato that only has a penny, and attach a new wire to the screw.
Step 10: Review Connections
In the end, this is what the connections should look like. Look carefully at the sides of the potatoes. Each potato in the battery should have one zinc side (screw) and one copper side (penny) with wires attached.
Leave out two wires, one going to a penny and one to a screw. These wires will connect to the lightbulb or the voltmeter.
Tip: if you wanted to add more potatoes for more power, make sure to follow this pattern! Each potato should have one screw and one penny!
Step 11: Test Your Battery!
lay the exposed wire on the bottom of the bulb or to the prongs of the voltmeter to see your battery in action!
Tip: For only two potatoes, we found that it didn't produce enough power for a lightbulb. We ended up adding more potatoes after we discovered this.
Step 12: Reflect and Learn!
How it works:
A potato battery is a type of battery that is known as an electrochemical cell. The chemicals zinc and copper (in the screw and penny/wire) react with each other, which produces chemical energy. This chemical energy is converted to electric energy by a spontaneous electron transfer.
The potato acts as a buffer and an electrolyte for the two metals. This means that it separates the zinc and copper, forcing the electrons trying to get from one metal to the other to travel through the potato and form a circuit. The electrons are able to flow through the potato because it acts as an electrolyte. The two metals would still react if they just touched each other without the potato, but without the barrier and electrolyte, the energy released from the reaction wouldn't form a circuit, which is what gets the power to the light bulb.
When the two wires are attached to the bulb it completes this circuit, turning the light on!
Step 13: Our Learning Process
Problems we solved: Since we found that two batteries couldn't power our lightbulb, we were disappointed at the prospect of only showing the potato's energy through the voltmeter. To solve this, we decided to add more potatoes. When that didn't work we found an LED light bulb instead of the regular, incandescent one we initially were using. Finally, the light turned on with four potatoes and an efficient LED bulb, which is why we added the option to attach more potatoes to the instructions and why our materials say to use an LED bulb, even though our picture includes the incandescent.
Other ideas: We played around with a few ideas before deciding to make a potato-powered light bulb and explaining how and why it worked. We thought about making a small wind turbine or water turbine to produce electricity, and talk specifically about benchmark M or I but decided against it mainly because Spencer had some prior knowledge on how to make the potato battery work. Additionally, we wanted to try to use the potato to charge our phones but found that it would take far too many potatoes than we could afford. In the end, we were all happy with explaining energy in relation to benchmark C and D through the example of a potato battery.