Last year we studied physics, and some of our physics experiments felt a little more like chemistry. I didn’t really mind this because I felt we had missed out on a lot of opportunities when we studied chemistry. This time we were looking at how to make a battery using pennies, aluminum foil, and paper towels. It was a great science lesson that had all of us working on how to get a project work right.
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Supplies to make a battery
copper pennies (this is going to be important), aluminum foil, paper towels, salt water (3 tablespoons per cup of water), voltmeter, 2 plastic-coated copper wires 4-6 inches long, scissors, wire cutters (you can possibly just use scissors), Focus on Middle School Physics lab book
Start putting your battery together
Cut out circles from the aluminum foil and paper towel the size of a penny.
Soak the paper towel circles in the salt water.
Expose the copper wires on your wires, and take one exposed end of the wire to a penny. Then take the exposed end of different wire and tape it to the aluminum foil.
Attach the other ends of the wires to the voltmeter. Measure the electricity
This is a simple cell.
Now, when we first attempted to measure our battery cell, we got nothing. That led us to start figuring this out what was wrong.
First, we called my father-in-law, a chemist who spent his entire life working at battery companies.
Our modern pennies are only copper plated, and it’s a very thin coating, only a few molecules thick.
The salt water is a rather low level and doesn’t provide much charge.
Problem-solving our homemade battery
First, we increased the amount of salt in our salt water mixture. This increased the voltage slightly but was still barely measurable.
Next, we tried changing the size of the paper towels. In the instructions, they emphasized how the paper towels touching each other would seriously mess with the voltage. We made our paper towel circles slightly bigger, but not too much bigger.
With these two changes in place, we tried again and were able to get a bit of an electric charge, but it was still fairly minimal.
Just to get an idea of what actually happens when you attach a real battery, we grabbed some AA batteries and we all watched in amazement as the voltmeter arrow jumped up quite impressively.
Overall, it was a bit of a let down for a science experiment. It was nowhere near as much fun as we had with an earlier experiment looking at Kinetic energy and smashing bananas.