This is a test of commonsense. Complete the next sentence:

How to create a potato battery
Gather the necessary materials.
To make a single potato battery you will need a potato, a galvanized nail, a copper coin, two alligator clip leads with clips on both ends, and a voltmeter.
Galvanized nails are standard nails that have a zinc coating.
They can be purchased at any hardware or home improvement store. Use a fresh potato as the experiment depends upon the juices inside the potato.