Skip to main content
Pearson+ LogoPearson+ Logo
Start typing, then use the up and down arrows to select an option from the list.

Anderson Video - Superconductors

Professor Anderson
Was this helpful?
Okay, has anybody ever heard of superconductors? Any of you guys ever heard of superconductors? You've probably heard that term in the news. Right? Sometimes they talk about levitating trains using superconductors in them. Okay. What is a superconductor? Anybody know? What is the -- what's the property of a superconductor? A superconductor is something that is super at conducting. Okay? It's right there in the name. In fact, it's so super that R doesn't just go to something small, it in fact goes to zero. Okay? And, this is very interesting to people who write because if you have a resistance that goes to zero, you can run current through these wires and they don't heat up. Right? There's no resistance there. That water flowing down the river doesn't experience any rocks in the river, and it just flows smoothly without any trouble at all. So if we think about our good old metals what we said was a metal looks like this. And, there's some resistance as a function of temperature, T. But a superconductor does the following: It goes down and then quickly drops to a resistance of zero. And then from there on out, it has a resistance of zero, all the way down. This temperature where it does that is called the critical temperature. Okay, superconductor drops to zero at some temperature that is not at absolute zero. So, the goal of superconductors is to find a temperature that is reasonable. You want that to be a high temperature. This is where all the research in superconducting materials has gone into. How do we push that temperature higher and higher? Okay? You want your metal wire to be able to operate at room temperature. Okay? Or, at least something remotely close to that. So, Where are they now? The current record, at least of a couple years ago, you can double-check me on this, maybe that's a little bit higher now. But, the current record is about 125 degrees Kelvin. Okay? This is something called mercury copper oxide. That's the material that it's made out of. Which -- 125 Kelvin that sounds a little cold still, right? Room temperature is like 300 Kelvin. But the point is, it is well above the temperature for liquid nitrogen. Liquid -- liquid nitrogen is about 77 degrees Kelvin. So if you take some of this stuff -- mercury copper oxide -- and you make a wire out of it and dip it in liquid nitrogen, all of a sudden it becomes a superconductor. It can conduct electricity with zero resistance. And this has interesting implications not just for carrying electricity but for carrying magnets on top of them. Okay? If you take a magnet and you put it on top of a superconductor, it levitates above the superconductor. And so, this is the goal behind these levitating trains: make superconductors, put magnets on the train, and let it levitate above it. And then, you can move things really easily. So, superconductor is a very interesting region -- interesting area of research. And basically, the whole idea is let's get this temperature even higher. Okay. All right. Let's check the time here. It is 1:30. I think maybe that's gonna be it for today. Tomorrow we're gonna start talking about electric power and how we understand power considerations in these electric circuits. Any questions before we take off? Nope? Ok. Cool. We're out of here. I will see you guys tomorrow morning Cheers!