Long hair vs. Van de Graaff generator

- Hello everyone, today I am here at the University of Sydney. I have a familiar face, Petr, around. - How is it going? - And this is Gabe and Liam. - Hey. - I guess everyone here is interested in physics, physical education and we have some experiments prepared for you. So the first one we have here, you may hear it booting up in the background, is the Van de Graaff

generator

. So I guess this all has to do with static charge and electricity. A small discharge of electricity can be seen between these two poles. Maybe Petr or someone else created this.

Tell me what your explanation is. - Well, so the basic idea is that, remember that experiment that you did hopefully in elementary school, maybe in high school where you take a plastic rod or a ruler and you rub it with a piece of cloth, a piece of felt and then put it next to some water or next to uh, like a tissue or paper or whatever and that stream of water is slightly attracted to that ruler... That's basically, it's separating the charges, right? TRUE? To create a pull, right? So that's what's happening here. There is one part of this contraption that is charging very strongly and the other part is not so strongly charged and then it sparks in the air. - Yes, it's like an electrical potential. - Yes, there is a gap.

As a rule of thumb, every inch that a spark goes through the air is between 15,000 and 30,000 volts, depending on the type of humidity and all that kind of stuff. So that's – - About 10 or 15 centimeters of space. - I would say 10. - Yes, I would say 10. - So, yes, that's a lot of volts. Someone do the math quickly, I'm not good at this. - Around 3000 or so. Three hundred thousand, sorry. - Three hundred thousand volts. - On a good day, this can generate about 30 centimeters of spark. Today is not a good day, but we had to do 30 centimeters earlier, which is... - It's scary. 900 - 900 kilovolts.

So, Liam, you're saying there's 300,000 volts and there's this thing here and there's a bunch of us around and there's this foam thing on the floor. - It's almost like it's hot here. - Yes, I'm worried. - So the way is it insulates you for what we'll probably end up doing. So you can play this safely and build up a lot of charge and hopefully we should see some interesting things happen with that. - So, this is so I can stand up and touch it safely. What if I touch it right now? What would happen to me? - It would hurt, yes, yes.

Instead of discharging into the ball of earth that is well connected to that earth so that it doesn't hurt. - Would they grind me? - You would be upset, yes. - Okay, so this is so that it stops being the floor? - Indeed. - OK. - Ideally. - Okay, I guess we should try it. - Should we try it? - OK, so, it was an idea that came up around the fact, I know that when you hold one of these, your

hair

starts to stand up on the end because I guess each strand of your

hair

has the same charge and they start to repel each other. with each of the strands of hair.

I guess I have pretty

long

hair so I might try removing mine and see if it does anything to the

generator

. My suspicion is that it's like my hair is too heavy, like each individual strand. I could, maybe the science witness here, maybe you guys can try it today, but I've never tried one of these on since I had it on my own. - Well, you could have tried to take science, it would be better to leave. - Let's go back to my classic

long

hair science series. - Yes, possibly 15 at the moment, so it's probably around 400,000. - In fact I have a wooden rod that they change.

I found it amazing, but... You can feel the attraction when you see the bouncing spark that the charges are throwing off. It's a nice little bounce effect, I'm not moving it at all. - No, I think it does have a good rebound. - Yeah. - That's so cool. - OK. - Alright. - Does anyone want to do a demonstration or should I go up first? - You go up first. - Okay, I'm standing here. - Stand on it. - Yes. - Maybe you take off your watch. - Normally it's totally safe, but I don't want to worry about breaking and not hurting you. - Okay, are you downloading it? - I'm downloading it right now, so what you need to do now is go ahead and ground yourself, to generate charge, let's get to work. - At hand now? - Both hands - Both hands.

Is better. Is he okay right now? Now I'm going to remove the dirt. - Yes. - So, you should feel something somewhere? - I do not feel anything. - OK. - But I can see the threads starting. - Yes, I think you can start to see her hair moving. - Can you shake your hair? - Yes. - Shake it. - Oh Lord! That is incredible! - How does it look? - That's so cool! - Cameraman, how are you? Are any of the longer strands affected? - They act like these longer strands should stick out a little. - And I didn't comb my hair. - These shouldn't hurt you. - Well... - "Shouldn't I"? - I might have to convince someone to move if you don't mind. - Okay, so John, can you see that? - Yes, yes, I can see it a little. - Is that a loaded rod? - No, this is just methacrylate, so it could be completely safe. - So, it shouldn't be – - You don't have it otherwise, there would be – - I mean, this one!

You can see this one here. - Oh Lord! That's so cool. - Let's take a look at the back. - That lock of hair there, that one is flying, from behind. - No, it's so amazing! My God! - So, you know, this is not the largest Van de Graaff generator, I did the same thing, but there are much larger ones where the charge accumulation would be much greater. - Yes absolutely. - So, I mean, I don't think I can go all out on this one. But maybe with a bigger one. - But seriously, so impressive. - I mean, that's still pretty - I had to take your picture. - Yes, that's amazing! - And you can see, it's clearly affecting the top of the hair.

All the hair on top is absolutely... - The first impression I have now, which is a little scary, is how conductive is the hair? If I touch one of your hair strands... - It's something like that, right? - Will this download? Will there be a spark between...? I don't believe it. But if you touch the ones in the back. - Yes, these ones here. - OK. Oh! It's a little... it's pulling towards me. Oh, that's walking away. That is approaching, that is moving away. - So, you're exchanging charges there, yes. - Yes Yes Yes. - Wow! - You're removing electrons from there. - Can I free myself from this without achieving it? - Toby, do you feel that? - I can feel that.

We have a spark. - That is incredible. - So, just hands up. - Hands up? - And then get off. Do not touch anything or anyone and you must ground yourself, your hair must fall downwards while the entire charge goes directly to the earth. - Okay, I'm going to take my hands off me. - And immediately, and then take a step back. You fall back to the ground without touching it and your hair falls out. And maybe bang your hands on the table a little before moving on. -Yes, he touches the table. - before touching the metal. - Oh Lord!

That was amazing! - Very good. - Great, hey. - Getting a spark. - Yeah, okay, well, my hair is pretty long, how about someone with short hair try it? Petr, you should go. - This should be being discharged or something. - Yes. - Fresh. Every time there is still a little spark. - Come on. - Alright. - I mean, there's always going to be something - - So, I think, Toby, this might be your experience too, every time I do this, there's this um, like I know the physics and I know it's safe and I trust. the team and I trust Liam and I trust the amount of years of education I have, but it still feels strange, and this still scares me and a little bad. - Yes.

I remember this was like one of those physics classes. But here I am like, yeah, now I was telling them I was scared. - Yes it is. - And it's like this... - Well, we have the only one we have here, around here. You can see the bottom is styrofoam and no one would be left empty until I show you it's safe. But I wasn't really sure because it had metal on it, how safe it would be when we loaded this. Sorry, I had to go up there. - Okay, so, Petr's hair, I don't know but I can see it. - Yours was good. - Yes, yours was really impressive. - But yours is going very well, yes. - I can not see it. - I know, I know, here I will show you. - Yours is definitely standing now.

Your hair was down here before. - You can see it? - Oh, wow! - It's pretty good. - Yes. Oh, wait, wait, as soon as I let you go... - No, as soon as you have a hand, it'll be fine. - No, but I feel... I feel... So, you can remove your hand and put it back. - Wait wait wait! Oh! Why does it make that noise? - That? The crunch? - The download. - Wow, you will have a different potential between there and there. - Yes, because you move there instead of your head. - So you can actually, don't do it yet, but you can take your hands off a little bit and then put them back on for a few seconds.

Look at that, I just saw your hair fall. - You're doing that. - Yes. - Because the charge goes to you and not to me. - Yes. Well, you see, now I'm acting like a lightning rod. - I can hear them still charging. - God, that feels so weird! - Yes. - Okay, so what I'll do now is let my hands go and then I'll put them back in a couple of seconds. - Yes, in three seconds. - And it should store the charge... - Because your charge should be the same. - Good. - So the reason you're not surprised is because you're under the same position as him.

When you remove your hands, you should maintain relatively the same charge because you are isolated from the ground and that will not accumulate much more charge. So you'll take it off and put it back on and you shouldn't get an electric shock. - That's all with the electrical potential. - Sure, I understand the theories. - You just want to hope that it's like, you know... - So, a year ago, there was a show with Todd Sampson called Life On The Line and I thought the premise was originally a bit boring and then, genuinely, when he made a jump on bungee with - with a phone book like connecting the two bungee cords, I thought "man, this guy gets it." This is really crazy.

It's one thing to know, you know, the theory and the tests and the other is to bungee jump with a phone book. - You have to have a lot of faith in mathematics, right? - Yes Yes. Okay, so three, two, one. One two three. Oooh! - Look, the hair doesn't fall back because you're still in the... - Yeah. - Oh, Oh, I just shot it across the table. - He will jump onto the table, yes, because that is land. - So, I'll get off, I'll unload and then we'll bomb again. - OK we will. - Alright. - Here we go. - You still have some charges. - I can still see your hair standing up. - Yes.

Just hit the table and you'll stop a bit. - Oh very good! Physics, right? - Good science guys, good science. - Good science. - I mean, I'm not sure if that was the spark or the actual wire. - That was perfectly timed with the spark. - Shouldn't we turn off the lights? - Well no, no. There was absolutely no time. It takes some time. Like we knew we'd done too much when that clock in the back turned into gibberish and... well, if they go down, they go back up to the ceiling. - You've done too much physics when the clock - Yes, the clock does that's great, it's been real down here. - We have decided to leave physics for today. - Yeah. - Okay, so we're rummaging through this cabinet looking for more experiments to use and Petr pointed out this strangely molten piece of metal and told me it's a lightning rod. - Yeah, it's a lightning rod that was actually at the University of Sydney and it was hit by lightning and then all the current around it basically created a strong magnetic field that basically came together.

So, it deformed like a solid, like the tube it is with a hollow opening as you can see and like the tube it shot up and closed there. He pinched himself. It's actually called the pinch effect and there's a demonstration of this here and we're not going to do it because one of the transformers is broken and we don't want to blow anything up. But if you put current here, it basically does that. - Yeah, and that's what happened to this little thing. - Yes. - Very well, let's go and do some more experiments. - Yeah.