High-voltage physics - with David Ricketts

happens. We can create very

high

voltage

s by using electromagnetic induction. Now this machine is much smaller than the Vander graph. and it becomes a much more popular machine for generating

high

voltage

and many of you may say, well, this is all fine, but I live in a normal home and we don't have Tesla coils and whims, hursts yuh, and these others, without However, it turns out that any of you who own a gasoline car have a gap Corf coil, so here I have an induction coil and you might not recognize this because you haven't looked at your engine recently, but you might recognize this as a spark plug. suitable for a penol, so this is what charges the spark plug and what I do is I have a little oscillator here that will turn the current on and off and that oscillating current should generate for us a spark, let's turn the lights on again and so on in each gasoline car has its room cor coil and it varies in the same way there are two coils here with a core that helps couple them now that we have done this and I have generated these high voltages and now what I want to do is show you some applications of high voltage so I have here this is the one that surprised me before it's just a smaller version of that and it puts out about 30 to 40,000 volts and um Dan you have an incentive yeah thank you so what I'm going to do is to turn it on and what I have here, can we bring the demo camera closer, really close, so what?

I have a sharp tip and then these cylinders are not so sharp and what's going to happen is that near the sharp tip I have a very high electric field and it's going to rip the electrons out of the air molecules and now the big heavy ion. the ion is the molecule without the electron, it will be accelerated through the electric field from the tip to the cylinders. Now this is big and heavy. If I'm creating the electric field, the force that moves it has an equal reaction to me, so it pushes me in the opposite direction, so we're going to push the air like this, we're going to push back a little bit on this, but let's see how much airflow we can generate from these ions flowing from the sharp to the um uh. rounded okay there's a lot of air here we go we understand you see all of that is caused by the electric field producing ions and then accelerating them towards the less sharp coils so this is known as ion thruster and if we can have a Ion thruster, do you think we can encounter an ion spacecraft or an ion ship?

Yeah, so let's see if we can make one of the ones I have here, an ion lifter. If you could zoom out, we could take a look at our nice triangle here and what I guess I'm going to do the same thing if you zoom in a little bit if you can see there's a sharp wire at the top and that sharp wire is the same as the nail. and then the bottom side is smoother and so those ions become softer. accelerated remember they tear on the sharp spot and always accelerate towards the soft spot, they don't tear on that soft spot so I'm going to turn it up and hopefully we can see if we can get something to fly.

Dan, if you want to take the incense, you see the air goes straight down, so we can use that electric field to accelerate the ions and allow us to do the actual flight, it's great, great, so these are some of the things that What I can do with these room Corf machines and here I created some ions. I want to talk now about something called plasma. Plasma is simply a collection of charged particles, they could be ions or electrons and we can do all kinds of interesting things with plasmas. And I want to show you a couple of these in the next three demos.

First, what should you never put in the microwave? Grapes. Yes, that is correct. Here I have the grape that I am going to cut in half. So I just cut a grape in half now, if you can take a look with the camera, let's set it up right, so what's going on? Why did the grape catch fire? It's like a tuning fork, so the microwave works at 2.4 GHz, a very fast frequency, but it works. the wavelength inside a grape is resonance, if the grapes were too big, the grapes would be too big to have resonance like a tuning fork, so what we are trying to do is tune our fruit to the exact resonance of its microwave, so it's a nice A cool demo, but probably for those who are on the side, you may have seen a little bit.

It's a bit of a pain to look in here, so Dan, do you have any ideas on how we could look better in the microwave? What are you going to do? They give hole in the back hole in the back only at the Royal Institution could we drill a hole in the back of your microwave? Please don't do this at home, we are not responsible and there you have it, it is a little difficult to drill. the hole there so I'm going to give you my phone and I think you know what to do so what we're going to do is I'm going to light the other thing you should never do is put a fire in the microwave so I'm going to light a candle and, um , you'll want to see if we can get a picture on the phone of what's there to put that in there, so I'm going to light my candle now, why am I lighting one? candle because a flame actually ionizes air so we're going to get some ions from this candle and my hope is that maybe the microwave can achieve a resonance that causes a plasma to form and if you're wondering what a plasma looks like if We're successful, you know we're going to get it again, we're going to let it have a little bit of air, but there we saw a plasma generated inside the microwave.

I'll give it one more chance to see if we can get some. Longer lasting plasma, by the way, part of the problem is the tealight. Wax does not like the microwave. I still haven't figured out why, here we go. We saw it the only time we could be in it for a while. for the microwave, but that's a fun way to generate plasma. Thanks Dan, perfect. Go ahead and put it on top. Now there are other interesting ways with the Room Corf machine in which we can generate plasma. Until now, when we were talking about the ion. elevators we were talking about uh, electric fields and air that destroy molecules.

What happens if we remove all the air? If we remove all the air, then there are no ions, the electrons can now flow freely from the two connections. This is exactly how a vacuum tube works. The caade tube works, so what we're going to do with the room machine here is, I'm going to turn it on and we're going to pull the vacuum out of this and initially we're going to see a spark. here and that spark will go out when an electron plasma stream starts to form here, so I'm going to keep it black until it forms because I think it disturbs the chamber.

Go ahead, thank you. You see it forming. How are you doing? So this is a current of electrons that goes between the top ball and the bottom ball and someone asked me once. Well, do electrons go from the bottom up or from the top down? My answer is I don't know, when? Thompson discovered the electron, this is how he did it: observe the fact that the electron is a particle, there is no positively charged particle, so he was able to observe the physical transfer of electrons. This is cool, but that's probably how it is. It's not surprising that you turn off the back because, in the late 19th century, it was very popular in cities like London, at the Royal Institution, to make as amazing a demonstration as possible and there was one demonstration in particular that was very famous for using the rorf coil. and that was called a gas fountain I'm sorry my French is horrible and what we're going to do is put this out and now I need to ired to tell you that there are two lovely items here that are not from the archive, however this is a really cool box, so I'm going to take it out, so it's just a glass cup, it's green because it's infused with uranium, that's how they used to make green cups and there's just a little bit of aluminum foil. at the top so now I'm going to place this here, we're going to do the exact same thing and the ball doesn't actually touch the foil inside, that's not as critical and now we're going to try this demonstration one more time.

You might want to video this if you make sure your torch light is off, I just want to make sure our seal is okay. Could I get some of the house lights? I just want to check our pressure, let's go down, okay? I'm going to turn it off and give it another quick try here, turn it off, thanks. I think our vacuum may not be low enough to do this, reset it please, here we go, it was worth it. I think as the load goes into the glass outside and down and there is a fountain around the glass and you have to admit that that would be very impressive in this exact theater in the late 19th century and this is one of the really nice things we can do with plasmas now there is one more Plasma that I would like to share with you and it is a very special plasma, so I have here a device that my students made and it contains an oscillator and an oscillator is like a swing and we are going to circulate a current.

By the way, this is just a cable. I made it with a very thin tube because it was nice and rigid, so we're going to oscillate a current here and, if you remember, you remember from

physics

class, the current is going to have a magnetic field that wraps around so we're going to have a field magnetic going around here now that in itself might not be too exciting so I want to add one more piece and it is once again in our special box so this is a custom made 2 L globe. Full of Zenon and nothing more and what I'm going to do is place this right there in the center, okay, now I'm going to touch it, you can't see anything.

J. Turn the lights down real quick, there's nothing there, let's bring the lights. go up a little bit so I can add a little bit of power, okay, nothing, there's nothing to do, so what I want to do is indu, if you remember induction was what we learned before. I want to induce some charge near the edge and hopefully that charge. then start circulating in the magnetic field and maybe we can get some glow or maybe some other very interesting phenomenon and to get that what I'm going to do is take my stick like I did before and see if hopefully there's enough moisture . let's turn off the lights, so now what we have is we've created a charge imbalance that's now circulating and I can go in and play and create some amazing things.

This is a plasma toroid and it forms and becomes a stable state within the world when you saw those little streamers, those little white streamers, when those streamers turn back on themselves, I'm going to take it down and see if we can't get the streamers back. , it will float back to the top, so if we can get one of these to circle back on itself, it will form a complete circular circuit and then absorb all the charge to form the plasma torus that we just saw and so Of course, last time it happened quickly and there we are. thank you it's completely self sustaining inside and just under power and you can watch it slowly rise in case you don't believe it's actually floating inside the balloon so this is the gaso source for today for 2023 it's here with the plasma toroid, thanks, we can have the lights on again, thanks Michael, it was nice of you to lend it to us and now I want to talk about our final instrument, you've probably already seen it here, how many of you recognize it? this guy here this is a Tesla coil and I'll have to ask Charlotte do you remember what year Tesla gave a lecture here by any chance? 1890 1890 Tesla stood here and demonstrated his Tesla coil now what's different about a Tesla coil?

The Tesla coil that the cor coil of this room is how many of you pushed someone to swing, yes everyone, okay, maybe you even swung, kicked your legs and stood up. Did you have to lift the person to their full height? No, just add a little power and the oscillation starts to resonate. What is different about a Tesla coil? These Tesla coils are we have the same inductor that we had in a hall machine or however, now we have a capacitor, it doesn't look like a capacitor. but when you have 100,000 volts or a million volts, this is a capacitor and it's going to resonate with the coil to produce extremely high voltages.

You can't see it very well. Do you want to get closer? It might help you see that there's a little bit, you can see some windings here, maybe that's the initial coil and you can see that it has about five turns and this is about, I don't know, 800 turns per eighth turn, my student has wound a lot of these, so let's see how this sounds. Well, just for security reasons I want to verify everything. This is a point. If you have any problems with ozone, it should be fine, but we will generate a lot of ozone with this one and the other one. um final demos so most people think maybe a Tesla coil is continuous but it actually only turns on for 20 microseconds a few million seconds and then turns off now it's just showing so why what do we hear?

We hear it because it's tearing apart air molecules and that creates a vibration in the air that our ears can hear, so it's those ions moving in the electric field that cause the noise and one of the really fun things we can do with coilsTesla is we can actually play music, let's see if we can bring our Tesla coil here to play a good song, okay, if we can hold the lights, I just pressed the wrong button, sorry, okay, let's give the Tesla a round of applause , so now this is amazing. little Tesla CL, but like the Hurst capricious machine, this one really isn't big enough for the Royal Institution, so I brought from America my own Tesla coil, which is so dangerous that I was required to put it inside the Faraday cage from the 1933 Christmas Conference and now we are all.

What would be great if we could turn on the lights in the house. This can also play music. Now, if both coils can play music, do you think we could ask them to do a duet? Would they be willing? Yes all. Right now, if I remember correctly, I promised you a million volts. Do you remember how big the spark is? It needs to be a meter in the US, it just needs to be a yard, it's a lower voltage in the US, okay Dan, could we take the coil out? Tesla? Yes, we are and Dan, if you could place it about three feet away and maybe bend it. the tip down a little bit, here we go if you're all wondering, this is a fiber optic cable to keep me alive, so I think we're going to, uh, if you can block this, Mike, we'll try it, I think.

That's fine, so let's test it a little and see what happens now. I want to pause here. I want you to look at the two fluorescent lights and notice that the one on top of the Faraday cage lights up and the one inside doesn't. The lights went out again, can you see that? Great now, if we turn the lights back on, we were chatting with the demo team and the question came up: is it safe to go into a Faraday cage? And my answer was, in theory, yes. They said I should show it in practice, so for safety reasons I need to disconnect so I don't be a Tesla coil inside you.

You got it, Mike. Okay, wish me luck if I don't see you. Thank you very much for coming. We took your PIN it's going to be fun okay uh you promised a meter yeah wait a second can we turn off the lights so you can say a prayer please more power W if you still have the power of speech we have a A few thanks to do before thanking Professor Rickets again. My name is Daniel Glazer. I'm the director of scientific engagement here. And before giving context to where the Faraday box is. Before I give context to what David has shown you today, I think.

You've got some shout outs you want to give, so I'm wondering if I can ask the demo team, that's Dan Mike Isa Tom Charlotte, to come out, because without these guys, come on, Charlotte, you don't have to download any of these. It would have been possible here, so why don't we get it, Dan Dan? I have something in the box for you, come take a look. I am getting the book that you will receive in this box which will be the most amazing demo. Have I ever seen it, thank you, there's a little sign up for you, you need the microphone, oh you want me to read it, okay two, the ri demo team, the most amazing people in the most amazing place, keep inspiring us all .

Professor rickets 24. of 6 23 you even did it the right way, well done, thank you very much, incredibly kind, everyone, so we need a little background for this. We got an email a couple of years ago, Charlotte and I'm from a guy at Harvard who was a fan of Michael Faraday and, although he was an original electrical engineer, his day job is doing innovation, but he decided to come here and do a bunch of experiments to take it to the end of the journey that ended. in the electric motor and if you've been to the museum below you'll see that the world's first electric motor was made by Michael Faraday and we thought it would be something fun to do and David came along towards the end of the cold era. and in recent years he has shown the most extraordinary generosity to RI, not least because he has given a bunch of sweatshirts and lab coats with his own initials - well, the first two letters of his name - to RI, but he has also developed ...again at his own instigation with his own funding many of the things you've seen here, which I think is fair to say David, you won't see anywhere else in the world most of these demos don't exist, you won't, There are not.

You won't see the cup and torus anywhere else. I don't think the Cup has been shown in 50 or 100 years, so there are things you'll see here that are practical and easy, and there are things that are borderline. of safety and practicality of technology and tonight they have taken it to the limit of that, but in a way that, as David said, since 1799 it has been happening in this theater and a lot of the discoveries and the technology that it has shown are from this same place, uh, the whim machine, for example, that you can see when you go outside, it's in the painting, uh, in the back, which is normally in the display case, but what he's done for us and I think that for us as individuals, for us as a community and for the people on the demo team is to take things out of their cases and put them to use, which is how we like them to be in the institution, with that historical context and in the very edge of science and security. uh we've had an extraordinary evening, please join me once again in thanking you for your lecture tonight, Dr.

David RS.