Making a potato powered light bulb is a fun way to better understand chemical reactions, and might even give you some relief from a power outage. First, you need to prep the potato. If you're planning on using the potato to power a clock (which only needs a little amount of voltage), you can cut it in half. Be prepared to use multiple potatos to light a bulb, because the voltage requirement is pretty high. Skin the potato (this isn't entirely necessary, but helps make things run a little smoother). Next, insert one copper wire into one end of the potato and insert the nail into the other. Wrap one end of the the other piece of copper wire around the galvanized nail. Touch the copper wire attached to the nail to the negative (-) conduit on the light bulb, and the other copper wire to the positive (+) conduit (if these aren't labeled, just try randomly then swap).