Here's why. The idea of using lemon juice stems from the basic science experiment known as the "lemon battery," where lemons, paired with zinc and copper, produce a small electrical charge.

There are a whole bunch of high school science experiments out there that are useful for teaching students the basics of biology, physics, and chemistry. One of the classics is the lemon battery.

Seriously, though, this demo made us question a few assumptions. First, when people do the potato- or lemon-battery experiment, they often use multiple lemons. Why? Hooking the pins up like ...