[Dr. Scott W. Tinker] Today we can fit our entire office into a laptop. In fact, we can almost fit it into a phone. This has changed the way we work, the way we communicate, the way we live. Part of this increased mobility comes from improvements in batteries. So, how do they work? All batteries have three parts: the anode (in this case some zinc-plated pipe), the cathode (here copper pipe). Now between them, I'll pour some regular grocery store cola, which becomes an electrolyte. The electrolyte is going to cause a chemical reaction in both metals. In chemical reactions, electrons move between different substances. There's a buildup of electrons in the copper side, and a loss of electrons on the zinc side. If we give these electrons some way to flow, like through this wire, the extra electrons here will move to balance the loss of electrons here. We can measure the pressure of that electron flow as almost exactly one volt. Now, let's take some more of these. These are very simple batteries. You need two different metals, and many things make an electrolyte acid. Like vinegar and, say, lemonade, saltwater, or even freshwater. Each of these makes about one volt. Now, when we connect all these cells together we get enough electricity to light this LED bulb. How cool is that? But it takes a lot of material and a lot of expense and the same is true in real life. This is an awesome electric vehicle, it's super fast and super quiet. It cost about the same as other luxury vehicles—around $60,000, but half of that is the battery. So, while batteries are great for mobility the trade-off is low power compared to their cost and weight.