 In this video, we're going to investigate how real batteries work. To explain this, I'm going to tell you about a hobby of mine, glass crafting. So when I was 16, I learned how to make stained glass decorations by soldering different pieces of glass together. The way that you do this is by wrapping pieces of glass together in copper foil so the edges have a nice copper colour, as you can see in the photo here. Then after this, you solder the pieces of copper together. So solder is usually made of lead and tin. So it's a nice silver colour, as you can see here. See the joints here are a nice silver colour? But sometimes when you are finished, you would like your solder to look a nice copper colour rather than this silver colour. In this case, what you would do is add a special chemical to the solder which would make the solder copper coloured. Here is a picture of a piece that I did when I changed the colour back to copper using this special chemical. I didn't know this at the time that the chemical was actually a solution of copper sulfate. To explain this colour change, take a look at the diagram here. Originally, there is a lump of metal, in this case magnesium, in a copper sulfate solution. But over time, the solution becomes clear and the metal changes colour and a copper layer forms around the outside. What happens here is that there are copper ions in the solution and that these copper ions steal electrons from the magnesium, forming copper metal and magnesium ions. For those of you who have studied chemistry, the equation for the reaction is shown. Two electrons move from each magnesium metal atom towards a copper ion. The reason that this occurs is because the electrons have a lower potential energy when they are attached to a copper atom than when they are attached to a magnesium atom. This diagram, which we have looked at before, is a simple way to understand the movement of electrons. They go from the high potential in magnesium to low potential in copper. This means that when the electrons move from magnesium to copper ions, they lose potential energy. Now to explain how a battery works, let's take a look at this setup. Here there is a rod of zinc metal in a zinc ion solution and there is a rod of copper metal in a copper ion solution. There is a special ion bridge joining the two solutions that allow ions to flow from one cell to the other. Electrons in the zinc have high energy, but if they were transferred to the copper, they would have lower energy. So let's investigate this with an energy position diagram. So here we have our zinc, our high energy level and then down here we have our lower energy level if the electrons move to the copper. So if the two probes are joined by a wire, as shown here, then electrons would flow from the high potential at zinc to the low potential at copper. This is how a basic battery works. It contains two metals of different potentials and once a wire joins the two terminals or the two metals, electrons flow from the high energy environment to the low energy environment. So that is a brief explanation of how batteries work. Thank you.