For my birthday this year, a friend of mine got me a "Plasma Mug."1 It's like those sound- or touch-activated glass plasma spheres, except that this is a mug, and I haven't tested to see whether or not it is sound-activated yet.
In case that wasn't a helpful enough explanation (for the two people who are going to visit this page, both of whom know what this is because they saw it in Real Life), and because I'm a dork, I'm now going to subject you to an explanation of what a "plasma sphere" is. Feel free to skip this paragraph if you already know, or if you don't care. (There will not be a quiz later.) Completely enclose a gas, such as neon (although in theory, any gas should work) in a relatively thin amount of glass. Without loss of generality, say that it's a sphere of glass, because "sphere" is a fun word to say. (According to my high school physics teacher, "so is 'hoop.' But not 'cylinder.'") Isolate this sphere, and charge it to just less than the electrical breakdown point of the enclosed gas. Emissivity constants can be found in the back of any good physics textbook. Now, when the glass is grounded, or even touched to the mild electrical field of a human, on the isolated other side of the glass from the charged gas, the slight differential in the field at that point will cause the enclosed gas to break down (and emit light), which is cool. (For bonus points, figure out how much less charge you need so that the energy transmitted by vibration will not typically cause this breakdown. Now you can have a plasma sphere that is (or is not) activated by sound as well as by touch.) Since plasma spheres are rarely at STP, and they wouldn't be exciting if they didn't do anything by themselves, most plasma spheres that are not sound-activated are charged to slightly beyond the breakdown point. This means that they glow all by themselves.
Now that the entire effect has been ruined by my explanation of how plasma spheres work, on to the pictures of the really neat plasma mug that I got! (Alert and studious readers will observe that the mug itself does not have a power cord attached to it. This reduces the risk of electrocution, and makes it easier to carry the mug around the house. Electricty is transmitted to the gas, through the glass, via induction - the base is powered, and runs an electromagnet, which thereby transmits current to the mug. This just goes to show that if you take enough E&M, it eventually sinks in to the point where you can bore people almost non-stop!)
One of the interesting things about the shape of the mug, what with the hollow handle and all, is that the charge will go through the handle, or up the side of the mug with the handle, but not both, because the breakdown will only occur across a voltage differential. Well, I found it interesting, at least.
Anyway, electricity is cool. Thank you very much for the lovely mug!
1) I also got a bunch of most excellent presents that are not listed here, mostly because they are slightly less photogenic, and a laundry list, despite appearances to the contrary, is not always suitable content for a web page. Insert appropriate and heartfelt text here about how the only thing that topped those gifts was the friendship of those around me. [This text not included due to a mild concern about causing incipient insulin shock in innocent readers.]
