(dramatic music) (audience clapping) - This is the first demo. So, Mike, would you come
out and give me a hand? So my little rod here is
charged and my little butterfly is charged with the same polarity. And it floats because like charges repel. There you are, Mike. See
if you can keep it going. There you go. (audience laughing) It is harder than you think. (metal clacking) Yeah, that's a trick we learned. Now he's got a white pipe. I have a different pipe and
I'm rubbing it with a very scientific plastic bag. No, there you go. Ah. - Okay.
- All right. All right, let me give you a hand. Let's see if we can get that going. Okay. It's a bit tricky. Yeah. Now, good job, Mike.
(audience clapping) Now his is repelling. But look at mine. Mine is attracting. A little higher. You see that? My pipe is oppositely charged. Oppositely charged attracts
the same charge. Repels. All right, fantastic. Thank you, Mike. (audience clapping) So thank you. So what was I doing there? I was busy. We were rubbing this pipe
and what we were doing is we were charging it up using a method known as tribal electric effect, tribal being related to friction. And I've got a beautiful
demonstration ball. This is my molecule. And when I rub it really, really hard, the electron comes off and
I've got a positive ion and I've got a negative electron. And that is what creates the charge. It's from the friction of just removing these two that are here. And I will put my molecule back. And so what's interesting is
that we can create positive and negative charge using
this method of friction. Now throughout the talk today, I'm gonna use this little wand. It has two little colours, blue and red. What they do is they
signify that there is charge and that that charge of
whether it's a red polarity or it's a blue polarity. All we care about is light charge repels, opposite charges attracts. So I have here a polystyrene,
two polystyrene plates and I'm gonna rub the
left one with my fur. (plate screeching) And I'm gonna rub the
right one with Teflon. (plate screeching) And let me see if I can
get my stick in here. Oh. I may have to rub again. (plate screeching) So today was the worst
day of all days in London to do static electricity examples. That's blue. Do you see the red? That's not a good enough red. Let's see if we can do better. Now if we're not getting the
red, the blue's coming back on. So let's try this one more time. We did see a little bit of a red earlier. I'm just gonna switch wands to see if this one's a
little bit more sensitive. Oh, you see a little
bit of red. You saw red. (audience laughing)
Come on. (plate screeching) All right. Yay. Okay. Thank you very much. (audience clapping) So the question is which one's positive and which one's negative? And this is a question that
we think is scientific, but in fact it's not. Most people think about polarity in charge related to the electron. Well, the electron wasn't discovered until the very late 1800s. So in Benjamin Franklin's
time when he was inventing the name of positive and negative charge, he had no idea about the electron. So he just had to guess.
And his guess was glass. When you rub glass with silk, in this case gonna do to Teflon, whatever it comes out is positive, and that is how positive is defined. Now let's see, will it do for me? Will either one? There we go. Do you see the red? I'll try it one more time. Perfect. So red is positive. That is how positive is
defined by a glass rod. And silk in this case, I used some Teflon. So you noticed here that I could
create positive or negative on the same material by using
two different materials. And in fact, what they did is they took all kinds of materials,
they rubbed 'em together and they went to see
which one was positive with respect to the other one. And they just put together what's called a tribal electric series. You can look it up on
Wikipedia and it goes through which materials you rub
with which materials to get positive or negative. Now what's interesting
is the word electricity. Electricity comes from
the Greek word for amber. Amber, the sap from the tree that hardens. They would take amber
and they would rub it and that would create a static charge, and that is where
electricity got its name. And that's also where
electron got its name. It's for the Greek word for amber. In fact, Michael Faraday
in this very theatre would take ceiling wax and
rub it against something to create a static charge,
and this is the first way that we as humans began
to generate electricity. Today's talk is very simple. We're gonna start with low
voltage, a few thousand volts, and we hope to end today's
show with over 1 million volts. If you're wondering how can I
demonstrate 1 million volts, it will make a spark one metre long. I hope that demo works. All right, so now I wanna
show you a couple interesting things we can do with electricity. I've shown you the tribal electric. The next thing I wanna
show you is induction. So. (audience laughing) It gets too much there. So what is happening is
my charge here is inducing a polarity on the can
where the opposite charge is on one side and the like
charge is on the other. And to share that with you, I actually have this balloon here. And it in fact will
operate just like the can. So what we have is this
is charge negative, which means all of the negative charge runs to the other side. And that leaves this side positive. Opposite charges attract. The positive is then
attracted to my negative stick as we can see right there. So what I do is I induce
a difference in charge. And this difference in charge
is gonna be one of the ways that we start to generate
higher and higher voltages. Now I have just shown you that demo. I saw that demo myself when I was younger and I asked myself, how
do I know he's just not making it up? (audience laughing) I mean, really, did any
of you see the electrons run over to the other side or the can? No. So I said to myself, how do
I prove that this is really what is going on? And so I would like to
demonstrate that for you. So I have here a Van de Graaff Generator. You may have seen it before. I will explain how it works later. For right now, I just wanted to generate a bunch of charge for me. And sorry about that. So my little charge wand here,
I'm just gonna turn it on. Turn on my wand. It is red. Everybody see it's red. Okay. So what I'm gonna do is I'm
gonna take two pieces of metal, and what we're going to do is
(wand thrumming) let me just do it the opposite. Oh, there we go. Here we go. So if red is negative,
all the negative charge will wanna go over here and this will become positive over here. Key thing is you notice
they're touching, right? They're just like the can,
one continuous piece of metal. So what I'm gonna do is I'm
gonna take both of these off. I'm gonna touch them together. And now, I told you before
a field was induced. You shouldn't believe me.
How can I prove it to you? I separate the two. And if this really had... Oh, let's go back in. (wand thrumming) Oh, there we go. This was red. Let's reset the red. These things go a little
crazy when this is on. Let's bring the red, let's reset. (wand thrumming) There we go. We get a
blue on both of these now. On both of those. So I'm gonna reset. It just does not like... You know what I'm gonna do? Put them close. I'm gonna separate. Let's see if that makes
this behave better. That was red, that was blue. All right, blue. Red will it come back on. Now will come back on. It's already lost. So there I've separated
the charge into two pieces and this is how we are gonna
generate higher voltages because we can induce charge and then we can separate things. Now I wanna show you the
next way that we generate high voltages and it's
called electro forests. And it is using the induction
that we just spoke of. So what I'm gonna do is take my fur. (plate screeching) I'm gonna rub this. And now, let's see what we got. Blue. Nothing. I'm gonna put this on top. I just put nothing on blue. Do I have any more charge
than the original blue? No. So I should be able to
go in and see my blue unless it's leaked off already. (plate screeching) There we go. I was just touching that. Can we get a blue? Can we
get a blue from anybody here? There we go. We got a blue. There's our blue. Now what I'm gonna do is I'm
gonna come in with this stick and all I've done is I've
taped a neon bulb to the end of the stick and when I get
a spark, you can't see it. So I'll just say ouch. But I wanted to show you one spark, so you know we did get sparks. Can we take all the lights down? All the lights down. Did you see it?
- Yes. - Okay. So what I've done now is I've taken all of the charge off of here. So there's no charge. I'm lying to you here as
I bring things around. So there's no charge on this.
And here's the question. Is there really no charge
or do I now have an equal and opposite charge on the metal plate as I did on the polystyrene plate? If I take them apart, see
if I can measure blue. Red, blue, red, right? So what I have done is I've
actually created blue charge by letting all of the red
charge that wants to repel go into my hand. And then what is all left
is the blue charge here. And so in doing that,
I'm able to create charge on a separate device. Now, that was a little
bit of a spark there. Let's just pick this back up.
(plate screeching) I can touch. I could transfer, I could touch. You can't hear it. But a spark. Spark, spark. You gettin' the idea? So I could actually do this all day. And if I had a good
insulator in the charge when it disappear, I could do
this for the rest of my life. Okay? Now people sometimes say,
well isn't that free energy, free electricity? No. Have you not seen me touch it,
move it, touch it, move it? I'm doing the work, I am
pumping the charge in and out and I'm doing the actual work, and that's how we get the work. But we can transfer that out of here. So now what's interesting
is I wanna show you with this little device,
and I'm gonna pull this up. We have a roaming
demonstration camera here. And I think Mike's gonna
try to zoom in on this. So what I wanna do is
I wanna charge this up. (plate screeching) Could we get the theatre- Oh, this is good. You guys can see me. And now I'm gonna change this. First of all, let's reset this to zero. Okay, we agreed zero. Oh, I did it backwards. (plate screeching) It's gotta go down, touch, transfer. And notice it stays at about 1.7, right? Don't look at the one that changes. That's just because I'm moving
the plate back and forth. 1.4, 1.7. You may say, well maybe you
lost all your chart here. So I'm gonna put a lot
more on, transfer it over. Oh, we got to two, that was pretty good. but I really can't get above 1.7 or two. Now why is that? It's because I can only transfer
charge, let's go to black, when the potential of this is higher than the potential of this. The potential for electricity is voltage. So when this has a higher
voltage, I can transfer charge. When they're at the
same potential, I can't. And so what I have here, just
to kind of illustrate this. And, Dan, could you take
the plinth away? Thank you. So I have two beakers of water here and I've already pre-siphoned them. And what I'm gonna do is I'm
gonna pour water into here and the water is charge. And the charge is being transferred from one to the other through this tube. Now intuitively, will
this level ever get higher than that level? No, it's exactly the same here. This potential can't get any
higher than that potential because we can't transfer any more charge when they have the same potential energy. So we need to figure out a
way to get to higher voltages. And what I'd like to do is
I'd like to introduce you to a pretty amazing apparatus here. This is Lord Kelvin's water dropper. Lord Kelvin demonstrated
this here in the theatre and I'm gonna get it working, hopefully. And what we're gonna do is
turn down the lights so you can see it operates and then I'll explain it. And so let's go ahead and get it started. It sometimes takes a little bit of... All right. Okay, it started up now. So if we could turn down the
lights and just look to where my hand is for a little flash. Could we get the lights
up just a little bit so I can check the metre? There we go. Did you see it? Back down. Now that it's flashing, let's see if we can get another flash. Will we get another one? I think we will. There you go. Did y'all see that? - Yes.
- So what we're doing is I'll let this run for a little bit. Do you want to hook up the electroscope? What we are doing is we are
creating charge from nothing. So first off, there's no current in these. I decided to make this out of copper pipe because I thought it looked nice. But what's happening here is that we are actually inducing charge. And I wanna just go over to
our little explainer here. Remember I told you about
charge separation here, right? So let's go over here. As the water comes down,
these two circles are charged. As they come down, we polarise the water and then you notice what happens. The drop falls, right? The drop falls. So the drop who had an
induced charge, falls away. And as a result, the
water drops have charge. What we do is we create
positive charge in this one, the positive charge repels the negative. Sorry, the positive
charge comes over here, attracts the negative, this goes down, this becomes negative, the
negative comes over here, it attracts positive
and it's a feedback loop that goes back and forth on itself. Now, Michael, is that working for us? Yes. All right, excellent. Can we get the camera up on the screen? It's working very well now. So if you look, as the voltage increases, they spread apart and then
there you go, that's perfect. That's great. That's great lighting. Spread apart. Spread apart. And then we get a spark
that comes out there. We're building up the
charge until we get a spark across here that lights up the lights. Now I wanna show you that
indeed this is how it works. So first off, I have here a charge stick. This is just like the fur and the PVC. It just does it automatically for me. So if you don't believe
that water can be polarised, (wand thrumming) Do you see that? Right. I'll do it for this side. See how it's attracted? It's attracted for the same reason the balloon in the can was. And so what I can do, I'm
gonna turn this back on and I'm gonna zero that all out. All right, do you wanna come and see if you can get the screen? So what I'm gonna try to do
here is the water's gonna flow through here and I'm
just gonna charge this up and just look at the number. (wand thrumming) (water trickling) There you go. You see it going up? All I've done, I just have
one loop here that I charge. It creates polarised water, which creates charge that
flows down into here. And that is how the Kelvin
water dropper works. All right. Thank you very much, Michael. Now this was an interesting
machine because it uses induction and it uses
gravity to do the work. The gravity is the one that's
going back and dropping all the water drops and
separating everything. There's other machines out there. How many of you have heard
of a Wimshurst machine? Anyone? A few of you. Well, we have from the 1933,
I believe, Christmas Lectures, the original Wimshurst
machine that was used there. And... I'm going to explain this in a minute, but I wanted just to first
for you to see what it does. Go ahead and start it up, Dan. (device thrumming) (electricity buzzing) Everyone see? I think probably you can see with the camera pretty well there. Everyone see? All right. So the question is, how
does this generate charge? Most people think while there's
something spinning inside, it must be friction. It is not. It is induction. All right, Dan, let's turn it off. And of course, being at
The Royal Institution, we can't have a small Wimshurst. We must bring on a giant Wimshurst
in order to explain this. So if we can get the demo
camera to come in tight to the disc here. So if you'll notice in the Wimshurst, we have a disc with metal foils on it. Let's see if you can maybe- You guys see them right
there? There they are. And we have the discs running. Here is my giant Wimshurst. Now, I'm gonna share with you the secrets in how this is able to
create much higher charge than we could before. Remember our two beakers of water, we couldn't go any higher than our source. What the Wimshurst is able
to do is to actually generate higher voltages using induction. And here's the key. So if I were to place
my metal pan above this, charge the bottom and touch
the top, you could say, oh, you're gonna induce a charge. We already saw you do that. But remember that with my little wand, when the two were together, I
had equal red and blue charge. Because the blue is made from the red, I can never have more. So I never get more
charge through induction when I just have one pan or the other. Take note, however, of... In the Wimshurst, there
are two pieces of metal next to the one that my
special electrode is over. And I put it to you that these two will induce a charge on this. And I wanna demonstrate that to you. What I'm gonna do is I am
going to charge up those two, see if our wands will cooperate with us. I'm gonna charge up these
two but not the centre one. So if I get any charge on
this, it must be from these two and I'm gonna take my charge stick. (wand thrumming) Charged up these two. Let's see if this will... They're both red, I think, yes. Okay. By the way, the reason you
sometimes see the blue flash is when I move it, it gets
an induced current in it. So that's why it's there. Very slight spark. (metal clacking) You see? My charge is now blue. So what I've done is
I've charged up these two and I've induced a little
bit of charge on this. So now what I'm gonna do is
charge up the middle one, charge up these two. Those really were charged
up. Just got a spark. I'm gonna get my one
charge from the bottom plus a bit and another
bit, the one plus two bits. Then I'm gonna rotate my wheel and I'm gonna do that again here. I'm gonna do that again here. Gonna do that again here. Here. Now while I'm doing this on the top, there's a partner of me on the other side charging up these bottom ones. When we come back around full circle, each one of these has one plus two bits because they are equivalent
to the one I did before. So now I have one plus two bits, one plus two bits, one plus two bits. So I'm immediately gonna get
one plus two bits on here plus a contribution, plus a contribution. I have more charge than I did originally and then I'm just going
to circle back around, and now I'm gonna have even
more charge and I will build up charge just like the Kelvin water drop. Did you notice I didn't start it? It started by itself just a
little bit of charge imbalance and then it has feedback that
builds more and more charge. And so the secret of the
Wimshurst is the fact that I get the charge from the one right beneath it. plus the two next to it, and
that's how I get more charge every time I spin around,
because as I spin, they come back and I can add
the more charges from sides. So that is the Wimshurst. If we could take that off,
and I'd like to show you some classic demonstrations
from The Royal Institution with this beautiful example
of a Wimshurst machine. And, Michael, if you
can clear the buckets. - [Michael] Sorry? - Clear the buckets when you
have a chance. Thank you. Great. So we're gonna start with the first one. And I don't know if
many of you are hunters, but we have here, a hunter. And this hunter is gonna
be hunting some birds. So. And what we're going to do is we're gonna charge this up and the birds are gonna get charged, and because they're the same charge, they're gonna fly apart. So let's go ahead and turn it on. Let's see if we can get
the birds to fly away. All right, so now the hunter
is looking for the birds. Can anyone help the hunter? Anyone help the hunter. Where should I go? Maybe in this direction. Excellent, excellent. He's looking around for some more birds. (device clacking) Fantastic. Comes back around. (device clacking) And I'm just going to for
this side over here, to see, oh, he keeps on shooting the birds. So you guys can see there. And now he's just really
going after all the birds that are there. All right, Dan, thank you very much. So that is a classic demonstration
of sparks in a fun way. We are now gonna do
one more demonstration. That is the thunder house. And Dan's gonna pull it out. And how many of you have
heard of a lightning rod? Okay, everyone. How many of you believe
that Benjamin Franklin actually took a key and put
it up on a kite and flew it? No, no, I don't think that's
actually what happened. But he was one of the first
to realise the power of being able to guide electricity in charge, realising that the lightning
we see are the same as the sparks we see down here. So what I have here is a lovely house. (indistinct) We use the other. Nope, Dan, it's right here. Here's what we need. I think you're missing a
bit in the centre though. Excellent. So I know this piece, my understanding, it dates backs to at least the 1930s. And I believe our head of heritage said perhaps a little bit earlier
or maybe even a lot earlier. I think it goes just in with friction. You can squeeze it like that. So we're gonna start with- Can we get the demo camera to come around? You can already tell
this is going to be fun. I have to put on safety, my PPE. Okay. so what I'm gonna do is I'm
gonna put on a lightning rod. Can you come around and take
a video of the lightning rod with the camera up there? So here's my lightning rod
and it's gonna go right down to the ground and I'm
going to just ground that. There we go. All right. So now any lightning that comes
in should go straight down the lightning rod and
we should all be safe. Dan, would you start the Wimshurst? (machine thrumming) Okay, we're building up. (electricity buzzing) Okay, we've got a little bit
of lightning there. You see? Right? It's not damaging. No one in the house is dying,
no one is catching fire. Everyone's very happy. So the lightning rod is a
really, really good thing. All right, so what we're gonna
do now is I'm just simply- Oh. (audience laughing) By the way, in preparing for these demos. That happens a whole lot. There we go. I'm gonna just adjust that. Now what I'm gonna do
is I'm gonna take away my lightning rod and now my
poor house is unprotected. Unprotected. Now I just want to refer you
to what is on my eyeballs and let us see what happens
in an unprotected house. Go ahead, Dan. (machine thrumming) (electricity buzzing) The house is apparently just fine. (audience laughing) Well, I'm not sure we
can open up this house to see what happens inside. Okay, we're gonna try a bigger spark. (house exploding)
(audience applauding) So I hope everyone will now have a lightning rod at their home. (audience laughing) Thank you, Dan, also for that sage advice, that we should get a
little bit larger spark. So that was the Wimshurst. And what I wanna do is I wanna come back to the Van de Graaff Generator. Van de Graaff was a professor
at MIT and he invented this generator in the late 1920s
and it's become very popular, and many people see it in a large areas. Let's just go ahead and start it. (machine thrumming) (electricity buzzing) Everybody can see the sparks? Everybody sees the sparks there? By the way, our cameras hate the sparks. So if you see a blue screen,
that's what's happening. Okay. So this is the Van de Graaff. It's generating around 100,000 volts. Up until now, we were around 10,000. The Van de Graaff's getting
us up to 100,000 volts. I'm just gonna turn it off. And I wanna show you how it works. So I'm gonna take the top off
and place it right over here. Okay, I'm just gonna turn it
on so that everybody sees that there's a belt going up and down. Everybody see that there's
a belt going up and down? And so there's little people
inside that are adding charge to that belt, okay? There's two ways to add charge. One is with friction. You can actually make the
rollers a different material or you can actually use a high
voltage source to do that. But when everyone explains
the Van de Graaff, what they do is they
just explain the charge moving up the belt from here to here. What they don't explain is the
key innovation of what makes the Van de Graaff really special. And I wanna show that key
aspect phenomena right here. This is what Professor
Van de Graaff figured out. So I'm going to place on
this a few thousand volts. And let me turn this on. Okay, so now I have a few
thousand volts on this. And what you wanna pay
attention to is this number. Just wanna make sure. There we go. So I've got a few thousand volts here. Hopefully when I touch it,
we can see the number go up. (metal clacking) Don't touch it, David. It's a few thousand volts. Okay, so this is just
like the belt, right? I'm transferring the charge. (metal clacking) If you think this is getting
old, try practising this. (audience laughing) (metal clacking) Okay, we're up to 46, 47, 48. We're not really getting much above. That makes sense, right,
because of this. Okay. So it doesn't seem like we
could get to 100,000 volts if we're just putting charge
here and floating it up because it just could go
as much high in potential as our little men down here could do. However, let's do something
slightly different. So what are we at now? Can you go back to this number
just to see where we are? (metal clacking) Okay, I'm just gonna get it back up to... All right, now is that 48? 41? Okay, watch now. (metal clacking) (indistinct talking) It's only a few thousand volts. All right, we're gonna have
to charge that back up. So let me zero that out, I apologise. Okay. (device beeping) (metal clacking) I gotta go back and do it. I'm sorry. (audience laughing) Is the number not changing? There we go. (metal clacking) (metal clacking) It is kind of therapeutic. (audience laughing) Okay, there. We're stopping at around 41. (metal clacking) This is not going where I want it to go. (audience laughing) (metal clacking) I think the humidity's gotten to me. (metal clacking) We're at 50. We were never at 50 before, were we? Of course I touched the side
and then we go back down. So you saw that we went above. And what it is, is that the Van de Graaff is actually a Faraday cage. The potential inside of here is zero. So in the outside, we charge
it up and we can't transfer any charge because it's
at the same potential. But the inside, all the charge cancels and we can continually
flow charge in there. Mike, could you come out with buckets? You have the bucket right there. So that is equivalent. If you remember, we had our
little demonstration here. (metal clacking) Let's turn that down. (audience laughing) All right. (object clacking) Mike has the bucket there. We'll lean this over. And now, imagine the potential in this one (water trickling) was zero as it is inside
of a Faraday cage. (water trickling) I could keep adding charge over and over and over and over again. (water trickling) Am I spilling?
- Yep. - Thanks.
(audience laughing) And this is how the Van de Graaff works, is by putting the charge in the centre, we are able to put much more charge. In fact, we could put an infinite amount of charge into this. When we put it inside, the
charge goes to the outside and it's zero inside. We can charge this up until this starts to break down the air. And the shape that breaks down the air the least is a sphere. And so that is why a Van
de Graaff has a sphere. But the key piece is the Faraday cage. And you notice, the little
(indistinct) put the charge on, that goes to the top, the
charge goes inside of the dome. And that is what's key to
how a Van de Graaff works. So we've done up here, all of
these have been DC charged. I wanna start taking you
into some other areas that we can look at. So over here, I have what
is called a Ruhmkorff coil. So I should start back. We're
at The Royal Institution. Michael Faraday discovered induction. This is a replica ring. So what he discovered
is if you put a current through one side... Can we go, oh wait. That's good. We got it up there. A change in current in one
side will cause a change in current in the other. And in this one, he has an
equal number of turns on these. And this is the basic
idea for what is known as a Ruhmkorff machine. And that is not the
inventor but rather simply the instrument maker that
made the best instruments. This coil is the same as the
original spark gap transmitter. And what I did is I bought one of these, and if we can go black on the top. And I bought a second
one and I took it apart to see how it worked. And so what we have
inside is we have one coil with maybe 200 turns and
then we have another coil with maybe 2000 turns. And the way this works is
we have a change in current in this coil and it gets
multiplied by the difference in coil numbers. So we have sort of a lever
to get us higher and higher voltages from the second coil. That's the first thing that this does. The second thing is the voltage
this produces is related to how fast we change the current. So the faster we can
change the current in this, the higher voltage we will get on that. And so our core is to do
lots of currents, high turns, switch it fast, and that is exactly what is inside of this machine. And I'm just gonna turn
it on so that you can... (device clacking) (electricity buzzing) So that's what happens. We're able to create very high voltages by using electromagnetic induction. Now this machine is a lot
smaller than the Van de Graaff and it becomes a much more
popular machine for us to generate high voltage with. And many of you may say,
well this is all fine, but I live in a normal
household and we don't have Tesla coils and Wimshursts
and these others. However, turns out that any
of you who owns a petrol car, indeed has a Ruhmkorff coil in it. So I have here an induction coil. And you may not recognise
this 'cause you haven't looked at your engine recently,
but you might recognise this as a spark plug, right, for a petrol. So this is what charges up the spark plug. And what I do is I have
a little oscillator here that's gonna turn on and off the current, on and off the current, and
that oscillating current should generate for us, a spark. (electricity buzzing) Let's turn the lights back up. And so in every petrol car,
you have your Ruhmkorff coil. And very much the same way,
there's two coils in here with a core that helps
couple them to gather. Now we've done this and we've
generated these high voltages. And now what I wanna do
is I wanna show you some applications of high voltage. So I have over here, this is the one that
was shocking me earlier. This is just a smaller version of that one and it generates around
30 to 40,000 volts. And, Dan, do you have incense? Yeah, thanks. So what I'm gonna do is
I'm gonna turn it on. And what I have here, can
we get the demo camera to come in close, very close. So what I have is a sharp
point and then these cylinders are not nearly as sharp. And what's gonna happen
is near the sharp point, I have a really high electric
field and it is gonna rip the electrons off the air molecules. And now the big heavy ion,
the ion is the molecule without the electron, it
is gonna 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 this
has an equal reaction to me. So it pushes on me in
the opposite direction. So we're gonna push air this way, it's gonna push back a little bit on this, but let's just see how much
air flow we can generate from these ions flowing from
the sharp to the rounded. (electricity buzzing) Okay. (air whirring) It's a lot of air. There we go. We get that? You see that? That is all caused by the
electric field making ions and then accelerating them
towards the less sharp coils. So this is known as an ion thruster. And if we can have an ion
thruster, do you think we can meet an ion spacecraft or an ion craft? Yes. So let's see if we can make one of those. I have here an ion lifter. If you could zoom out
and we could take a look at our nice triangle here. And what I'm gonna do is the same. Just close 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 get accelerated. Remember, they get torn
apart at the sharp place and they always accelerate
to the smooth place. They don't get torn apart
at that smooth place. So I'm gonna turn this up
and hopefully we can see if we can get something to fly. (electricity buzzing) Dan, if you wanna take the incense. Do you see the air going through? Going directly down there. So we're able to use that
electric field to accelerate ions to allow us to achieve actual flight. It's pretty cool. Excellent. So this is some of the things we can do with these Ruhmkorff machines. And here, I created some ions. I wanna talk now about
something called plasma. Plasma is simply a collection
of charged particles. They could be ions or
they could be electrons. And we can do all kinds of
interesting things with plasmas. And I wanna show you a couple of these in these next three demonstrations. So first off, what should you
never put in the microwave? Grapes. Yes, that's correct. (microwave beeping) So I have here, a grape. Just gonna cut it in half. So just cut a grape in half. Now you can take a look with the camera. Let's just set it up.
(microwave beeping) (audience clamouring) All right, so what is happening? Why did the grape catch fire? It's like a tuning fork. So the microwave runs at 2.4
gigahertz, very fast frequency. But it turns out the wavelength inside of a grape is resonant. If the grapes were too big,
the grapes would be too big to have resonance like a tuning fork. So what we're trying to do is
tune our fruit to the exact resonance of our microwave. So that's a pretty cool
demo, but you probably, for those on the side, you may have seen a little bit in here. It's kind of annoying
to look through here. So, Dan, do you have any
ideas on how we might be able to look better into the microwave? (tool buzzing) What are you gonna do, Dan? - Hole in the back? - Hole in the back? (tool buzzing) Only at The Royal Institution
would we drill a hole in the back of your microwave. Please don't do this at home. We are not responsible. And... There you go. It's a little bit difficult
to drill a hole there. Dan, I'm gonna give you my phone and I think you know what to do. So what we're gonna do is I'm gonna light- The other thing you should never do is put fire in the microwave. So I'm gonna light a candle
and you're gonna want to see if we can get a picture on
the phone of what's there, to put that up there. So we're gonna light my candle. Now why am I lighting a candle? Because a flame actually ionises the air. So we're gonna 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, like,
what's a plasma look like? If we're successful, you'll know. (glass clacking) (door clicking)
(microwave beeping) (audience clamouring) Gonna get it again. I'm gonna let that have
a little bit of air. But there, we saw a plasma generated inside of the microwave. (instructor blowing) I will give it one more
shot to see if we can get a little bit longer lasting plasma. By the way, part of the
problem is the tea light wax doesn't like the microwave. I haven't figured out yet why. All right. (door clicking) (microwave beeping) Gah, all right. Well we saw it the one time. We could be at this for a
while for the microwave, but that's one fun way
to generate some plasma. (door clicking) Thanks, Dan. Perfect. Go ahead, put it on top. (door clicking) (microwave beeping) (microwave thrumming) (microwave thrumming) Now there are some other interesting ways with the Ruhmkorff machine that
we can generate some plasma. So up until now, when we
talked about the ion lifters, we were talking about electric fields and air ripping apart molecules. What happens if we remove all of the air? If we remove all of the
air, then there's no ions. The electrons are now free to
flow from the two connections. And that's exactly how
a vacuum tube works, catheter array tube works. And so what we're gonna do
with the Ruhmkorff machine here is I'm going to turn it
on and we are gonna take the vacuum out of this. And initially, we're gonna
see a spark right here. And that spark is gonna die
away when a plasma stream of electrons starts to form over here. So I'm gonna, let's keep
it black until this forms, 'cause I think it disturbs the camera. (electricity buzzing) Go ahead. Thank you. (electricity buzzing) You see it forming? (audience clamouring) How's that? So this is a stream of
electrons going between the top ball and the bottom. And someone asked me once,
well, are the electrons going from the bottom of the top or
from the top to the bottom? My answer is, I don't know. (audience laughing) When J.J. Thompson
discovered the electron, this is indeed how he did
it, was to look at the fact that the electron is a particle. There is no particle of positive charge. So he could actually look at the physical transfer of electrons. Now this is super cool, but it probably does not surprise you, (indistinct) that in the late 1800s, it was very popular in
towns such as London at The Royal Institution to do as amazing a demonstration as you could. And there was one particular
demonstration that was very famous for using the Ruhmkorff coil, and that was called Gassiot's Fountain. Sorry. My French is horrible. And what we're gonna do is
we're gonna take this out. And now I'm required to
tell you that there's two precious items in here, they
are not from the archive. However, this is just a really cool box. So I'm gonna pull this out. So this is simply a glass goblet. It is green because it's
impregnated with uranium. That's how they used
to make green glasses. And there's just a bit
bit of tinfoil in the top. So now I'm gonna place this here. We're gonna do the exact same. And the ball is not really
touching the tin foil inside. That's not so critical. And now we are going to
try this demonstration one more time. (electricity buzzing) You may wanna video this. If you do, make sure your light is off. Your torch. (electricity buzzing) Just wanna make sure our seal is good. (electricity buzzing) Could I get a little
bit of the house lights? I just wanna check our pressure. We are going down. (electricity buzzing) Okay, we're gonna turn it off and give it another quick try here. Turn that off. Thank you. I think our vacuum may not be
down quite enough to do this. Start it again, please. (electricity buzzing) There we go. It was worth, I think, the wait. The charge is going into the
glass, outside and back down. And it is a fountain all around the glass. And you have to admit, that
would be very impressive in this exact theatre in the late 1800s. And this is one of the
really pretty things we can do with plasmas. (audience clapping) Now there's one more plasma that I would like to share with you. And it is a very special plasma. So I have here, an apparatus
that my students made And, (device beeping) it contains an oscillator. And an oscillator is just like a swing, and we're gonna circulate a current. By the way, this is just a wire. I made it out of very thin tubing because it was nice and rigid. So we're gonna oscillate
a current in here. And if you remember, you
remember from physics class, the current will have a magnetic
field that wraps around. So we're gonna have a magnetic field that circulates around here. Now that in itself might
not be too exciting. So I wanna add one more
piece and it is once again in our special box. (box clacking) So this is a bespoke globe, two-liters, filled with xenon and nothing else. And what I'm gonna do is place this right there in the centre. Okay, now I'm gonna touch it. There's nothing to be seen. Just take the lights down real quick. There's nothing there. Let's bring the lights up a little bit. So can add a little power. Okay. Nothing there, nothing coming on. So what I wanna do is I wanna induce, if you remember induction
was what we learned earlier, I wanna induce some charge near the edge, and hopefully that charge
will then start to circulate in the magnetic field, and
maybe we can get some glow or maybe some other very
interesting phenomena. And to get that out, what I'm gonna do is take my stick as I did before. And let's see. Hopefully,
there's not enough moisture. Let's take the lights down. (audience clamouring) So now what we have is we've
created an imbalance of charge that's now circulating around
and I can come in and touch, and create some amazing things. This is a plasma toroid and
it forms and becomes a steady state inside of the globe. When you saw those little streamers, those little white streamers, when those streamers
come back on the cell. I'm gonna turn it down and see if we can't
get the streamers back. It's gonna float back to the top. And so if I can get one of
these to circle back on itself, it'll form a complete circle circuit. And then that will suck all
of the charge in to form the plasma toroid we just saw. And of course, last time
it happened quickly. And there we are. (audience clapping)
Thank you. It is completely self-sustained inside and I just lower the power
and you can see it's slowly rise up in case you didn't
believe it's actually floating inside of the globe. And so this is Gassiot's
fountain for today, for 2023 is right here with the plasma toroid. Thank you. Can we have the lights back up? (audience clapping) Thank you, Michael. It was kind
of you to loan that for us. And so now I wanna talk
about our final instrument. You've probably already seen it here. How many of you recognise
this guy right here? This is a Tesla coil. And I'll have to ask Charlotte here. Do you remember what year
that Tesla lectured here, by any chance? - [Charlotte] It's 1890. - 1890, Tesla stood right
here and did a demonstration of his Tesla coil. Now what is different about a Tesla coil than this Ruhmkorff
coil is how many of you pushed someone on a swing? Yeah, everyone. Okay. You maybe even have swung
yourself and kicked your legs and got you up. Did you have to lift
the person all the way to their maximum height? No. You just add a little bit of energy and the swing starts to resonate. What is different about a
Tesla coil, these Tesla coils, is we have the same inductor that we had on a Ruhmkorff machine. However, now we have a capacitor. It doesn't look like a capacitor. But when you're 100,000
volts or a million volts, this is a capacitor and
this is going to resonate with the coil to produce
extremely high voltages. You can't see it very well.
Do you wanna come in close? Might help you to see
there's a little bit of a, you can see some windings here, perhaps. That is the initial coil,
and you can see this is about five turns and this is
about, I don't know, 800 turns, 1000 turns. My student has wound many, many of these. So let's get and take a look
at what this sounds like. Okay, so just for safety
reasons, wanna check everything. This is a point, if you
have any issues with ozone, should be fine, but we will be generating a lot of ozone with this and
the other final demonstrations. (electricity buzzing) So most people think that maybe
a Tesla coil is continuous, but it really just comes
on for 20 microseconds, few millions of a second,
and then turns off. (electricity buzzing) All right, now it's just showing off. (audience laughing) So why do we hear it? We hear it because it's
ripping apart air molecules. And that's creating a vibration in the air which our ears can hear. So it's those ions moving
in the electric field that causes the noise. And one of the really
fun things that we can do with Tesla coils is they
actually can play music. Let's see if we can
get our Tesla coil here to play us a nice song. (electricity buzzing) We can hold with the lights.
I just hit the wrong button. Sorry. (upbeat electric music) (upbeat electric music) All right, let's give the Tesla coil a round of applause.
(audience applauding) So now this is an amazing
little Tesla coil. But like the Wimshurst machine,
this really isn't big enough for The Royal Institution. So I brought all the way from
America, my own Tesla coil, which is so dangerous that they
require that I put it inside the Faraday Cage from the
1933 Christmas Lectures. And here we are. (electricity buzzing) Now, what's great, if we could
bring the house lights up, this one can also play music. (upbeat electric music) (audience clapping) Now, if both coils can play music, do you think we could
ask them to do a duet? (audience laughing) Would you be willing? Yes. All right. (upbeat electric music) (upbeat electric music) (audience clapping) Now if I recall, I did
promise you a million volts. Do you recall how big
the spark needs to be? A metre. In the US, it only has to be a yard. It's lower voltage in the US there. All right, Dan, could we
take the Tesla coil out? Yes we are. (person laughing) And, Dan, if you could place
that approximately a metre away and maybe bend the tip down a little bit. There we go. If you're all wondering,
this is a fibre optic cable to keep me alive. So I think we're just going to... If you can lock this up, Mike,
we will get this tested away. I think that's good. So let's just test it out a
little bit, see what happens. (electricity buzzing) Now I wanna pause here. I want you to look at the
two fluorescent lights, and notice that the one on
top the Faraday cage lights up and the one inside does not. Take the lights down again. (electricity buzzing) Can you see that? Excellent. Now if we
take the lights back up. We were having discussion
with the demo team and the question came up was, is it safe to go inside of a Faraday cage? And my answer was, in theory, yes. (audience laughing) And they said I should
show it in practise. (audience laughing) So. For safety reasons, I
need to unplug myself, lest I be a Tesla coil
inside the Faraday cage. You got it, Mike? All right, wish me luck. If I don't see you, thank
you very much for coming. (audience laughing) (indistinct talking) (person laughing)
Yeah. (indistinct talking) It's gonna be fun. (audience laughing) All right, Mike, you promised one metre. - [Mike] Yes. Hold on a second. (indistinct talking) We can turn down the light
so I can do a prayer. (audience laughing) (electricity buzzing) More power. (audience laughing) (audience clamouring)
(electricity buzzing) (audience applauding) - He still has the power of speech. We've got a few thank yous to do before we thank Professor Ricketts. Again, my name is Daniel Glaser. I'm the director of
science engagement here. And before I give context to- Where's the Faraday box? Before I give context to what
David has shown you today, I think he's got a few thank
yous that he wants to give. And so I wonder if I
can ask the demo team, that's Dan, Mike, Eila,
Tom, Charlotte to come out because without these guys... Come on, Charlotte. You have to move down. None of these would've been possible. Here. (audience clapping) So why don't we get Dan. Dan, I have something in the box for you. Come take a look. - I'm getting in the box? - You're getting in this box. That is gonna be the most
amazing demo I've ever seen. (audience laughing) - [Dan] Thank you. (box clacking) - [Instructor] There you are.
A little inscription for you. You need the microphone. - Oh, you want me to read it? Okay. To the RI Demo Team,
the most amazing people at the most amazing place
keep inspiring us all. Professor Ricketts,
24th of the sixth, '23. You even did the date
the right way. Well done. - Thank you.
(audience laughing) (audience clapping)
- Thank you very much. (indistinct talking) That's Professor Ricketts, everybody. (audience applauding) (indistinct talking) - So we do need a little
bit of history for this. We got an email a couple of
years ago, Charlotte and I, from this guy in Harvard who
was a fan of Michael Faraday's. And although he was originally
electrical engineer, his day job is doing innovation. But he decided to come here
and do a bunch of experiments to lead to the end of the journey, which culminated in the electric motor. And if you've been to
the museum downstairs, you'll see the world's
first electric motor was made by Michael Faraday. And we thought that would
be a fun thing to do. And David came towards
the end of the COVID time. And over the last couple of years, he's demonstrated the most extraordinary generosity to the RI, not least
because he's given a bunch of sweatshirts and lab
coats with his own initials or the first two letters
of his name to the RI. But also, he's developed,
again, as his own instigation with his own funding, many of the things that you've seen here, which
I think is fair to say, David, you will not see anywhere
else in the world. Most of these demos do not exist. - You will not, there is
not the cup and the toroid you will see nowhere else. Correct.
- I don't think the cup's been shown for 50 or 100 years. - So there are things
that you'll see here, which are practised and easy. And there are things at the very edge, both of technology,
safety and practicality. And this evening, you've been taken to the very edge of that. But in a way, which as David has said, since 1799 has been
happening in this theatre, and a lot of the discoveries
and the technology that he's shown are from this very place. The Wimshurst machine, for example, you can see when you go outside, is in the painting at the back there, which is normally in the display case. But what he's done for us, and I think for us as individuals,
for us as a community, and for the people in the demo team, is to take stuff out of their
cases and put them to use, which is like, we like them to
be at The Royal Institution. So with that historical context and at the very cutting
edge of science and safety, we've had an extraordinary evening. Please join me once again in thanking your lecturer this evening,
Dr. David Ricketts. (audience applauding)
