What's Going on Here?!
It is pretty simple actually. We have three different common household fruits: banana, orange and apple. Copper (Cu) and Zinc (Zn) nails are inserted into the acidic fruits (apple and orange) and the nails are connected through the banana with small metal wires. Lastly, a simple 5 Volt USB cable is being used to charge an iPod.
So How Does It Work?
The energy that we get to charge our iPod is coming from an electron exchange in the metals between the fruits. Both nails are undergoing a chemical reaction caused by the acid in the citrus fruits. The Zn atoms are being dissolved into Zn ions that are positively charge (give two negatively charged electrons). The Cu nail has an oxidized tarnish (Copper Oxide) that dissolves in acid. The Copper ions attract the negatively charged electrons to neutralize the ions into Cu metal.
The banana is necessary, because it is relatively neutral (pH) and will continue to conduct the electron flow. This creates a circuit. The USB cable is able to enter the circuit and continue the electron flow and receive enough of an electrical charge to briefly charge an iPod.
How Does this Compare to a Battery?
Technically this would be considered a fuel cell, but the idea is very similar. In fact, the type of fuel cell that we see created is very similar to the very first chemical battery invented in 1800 by Italian physicist Count Alessandro Volta, namesake of the volt. His design is the foundation for the modern battery.
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