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Should a Person Touch 200,000 Volts? A Van de Graaff generator experiment!

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08:19   |   May 17, 2010

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Should a Person Touch 200,000 Volts? A Van de Graaff generator experiment!
Should a Person Touch 200,000 Volts? A Van de Graaff generator experiment! thumb Should a Person Touch 200,000 Volts? A Van de Graaff generator experiment! thumb Should a Person Touch 200,000 Volts? A Van de Graaff generator experiment! thumb

Transcription

  • Frostbite Theater presents...
  • Cold Cuts! No baloney!
  • Just science!
  • Now, what'll happen if a person were to touch it?
  • Or, maybe a better question is, "Should a person touch it?"
  • [Audience] Yes!
  • Well, maybe yes, maybe no.
  • Do you guys know what voltage is?
  • What does voltage measure?
  • It's actually a measurement of energy per charge.
  • Do you know how many volts are in a flashlight battery? One of those D-cells?
  • [Someone in the Audience] One point five!
  • One point five! Very good!
  • How many volts in a nine volt battery?
  • [Audience] Nine!
  • Nine! That's why they call it a nine volt battery!
  • How many volts come out of the wall?
  • [Someone in the Audience] One hundred twenty!
  • About a hundred and twenty.
  • How many volts on that?
  • When that thing's running well, it's about two hundred thousand.
  • Okay, so think about this for a second.
  • Can you safely touch a flashlight battery?
  • [Audience] Yes.
  • Yeah! Can you safely touch a nine volt battery?
  • [Audience] Yes.
  • Yeah! Can you safely stick your finger in the outlet?
  • [Audience] No!
  • No! So if you can't touch a hundred and twenty volts, should a person touch two hundred thousand?
  • [Audience] Yes/no!
  • Probably not. But, do you want to see it anyway?
  • [Audience] Yes!
  • That's what I was afraid of...
  • [Audience] It's not on!
  • I know it's not on.
  • But there is something I am on that I don't want to be.
  • The ground.
  • What's this?
  • [Audience] A stool.
  • A stool made from...
  • [Audience] Plastic!
  • Which is an...
  • [Audience] Insulator!
  • I'm going to get on the stool.
  • Not because I'm short, but because I want to get away from the ground.
  • If I'm down here, the only insulation I have is whatever's in my shoe.
  • Not that much.
  • If I'm up here I've got my shoe, and I have nine inches of plastic?
  • Something like that.
  • Hopefully, hopefully it's enough insulation the electrons won't flow through me and into the ground.
  • They'll just gather on me.
  • If they just gather on me, what should happen?
  • What hair I have left should stand up.
  • Three... Two... One...
  • Argh!
  • Doesn't hurt.
  • Anything happening?
  • I'm hoping hair is doing something.
  • But, at any rate, I'm not dead, which is a good start.
  • Now, how many volts are on my left hand.
  • [Someone in the Audience] A bunch.
  • How much is a bunch?
  • [Someone in the Audience] Two hundred thousand.
  • About two hundred thousand.
  • What'll happen if I touch the dome with my right hand at the same time?
  • Argh!
  • Nothing! Why does nothing happen?
  • How many volts on my left hand?
  • [Audience] Two hundred thousand.
  • Two hundred thousand. How many volts on my right hand?
  • [Audience] Two hundred thousand.
  • Two hundred thousand. What's the difference?
  • [Someone in the Audience] Nothing.
  • There's no difference. Electricity flows from high voltage down to low voltage.
  • If it's the same voltage, it doesn't move around.
  • It's like having a bathtub full of water.
  • If all the water's at one level, the water stays put.
  • Have you ever seen birds land on the power lines?
  • They don't get killed?
  • Same reason. Both their feet are at one voltage.
  • They might get a little bit puffy, but they don't get killed.
  • Now, what would happen instead of this dome,
  • I touch the grounding dome with my right hand.
  • How many volts would be on my left hand?
  • [Audience] Two hundred thousand.
  • Two hundred thousand. How many volts would be on my right hand?
  • [Someone in the Audience] Two hundred thousand.
  • Uh, ground is zero. Defined as zero. What's the difference?
  • [Someone in the Audience] Two hundred thousand.
  • Two hundred thousand. That's like a waterfall.
  • The electrons will flow from a high voltage down to a low voltage.
  • In fact, if you listen carefully when I point at the dome...
  • What's that sound?
  • [Someone in the Audience] Electrons!
  • Yeah, those are electrons flying off my finger.
  • You'll notice... Watch my hair when I point.
  • Why does my hair go down?
  • Yeah, if the electrons are flying off my finger,
  • they're not on my head to make my hair stand up.
  • And you'll notice that also it doesn't do it when I make a fist, but it does when I point.
  • It turns out charges jump off of points easier than they jump off of rounded things.
  • That why these things are round, so they can gather the charge.
  • Know what a lightning rod is?
  • [Audience] Yes.
  • What's a lightning rod?
  • Pointy piece of metal.
  • People think it's there to attract lightning.
  • It's actually there to bleed charge away so lightning doesn't strike.
  • In my pocket, I have that nail.
  • It's like a lightning rod.
  • If I let go of the point, if your ears are good, you can hear it whistle.
  • If your eyes are good, you can see when I cover the point, and I let go of the point, my hair moves up and down.
  • I don't know if you can see it, but I can feel it. I can feel it moving.
  • It's more obvious, though, instead of pointing at the audience, if I point here.
  • Okay, so again, why is my hair going down?
  • [Audience] Losing electrons.
  • I'm losing electrons! The electrons are flying off the nail to the dome.
  • And, if I get it close enough, we can actually make a little spark that we can see better if Mr. Dave turns the lights off.
  • A little spark.
  • Lights back on.
  • So that little spark tells you something.
  • For there to be a spark there, the electrons have to come from the dome,
  • through me, out the nail to that dome.
  • If electricity's flowing through me, why am I not dead?
  • [Someone in the Audience] You're insulated from the ground.
  • I'm not insulated. That's the ground. I'm touching the ground.
  • I'm not disappointed, I'm just confused. Why an I not dead?
  • Well, I mean, if you like, I can come down here.
  • What's my hair doing?
  • [Someone in the Audience] Nothing.
  • Nothing! Where're the electrons going?
  • [Someone in the Audience] To the ground.
  • Through my feet into the ground.
  • If I get up here, I block them.
  • So if electricity was flowing through me, why am I not dead?
  • Again, this is not a major disappointment on my part. But, why am I not dead?
  • Do you know what current is? Like in a river? What does current tell you?
  • Yeah, which way and how much.
  • Which way is the water flowing and how much water is flowing.
  • For electricity, what does current tell you?
  • Which way and how much.
  • Right, is this a high current or a low current?
  • It's low. That's why I'm not dead.
  • There's just not that much electricity flowing through me.
  • If this were a high current, what would happen?
  • [Audience] You'd die.
  • Yeah, I'd die, and in kind of a gross way.
  • Have you ever cooked a hot dog in a microwave?
  • [Audience] Yes.
  • Ever forget to poke holes? What happens if you don't poke holes?
  • [Someone in the Audience] It blows up.
  • It blows up.
  • Right, because the water inside changes to steam and it needs to get out somehow.
  • Well, if this were a high current, the same thing would happen to me.
  • My blood would boil and I'd blow up all over the room.
  • It would be an experiment you do only one time.
  • That's also why you don't stick your finger in the outlet.
  • Even though the outlet is only a hundred and twenty volts, it's a high current.
  • It's really the current that gets you and not really the voltage.
  • Now then, what'll happen to my hair if I let go of the dome?
  • [Audience] It goes down.
  • Stay up, mostly. How come?
  • I'm insulated! I'm insulated and there's nowhere for the electrons to go
  • except from the water vapor in the air.
  • If I want to get rid of it quickly, what do I need to do?
  • [Audience] Step down.
  • I need to step off.
  • And as soon as I step off, I get a shock through my foot and the electrons leave me that way.
  • By the way, this is how a lightning rod works.
  • Here's your thunderstorm.
  • You have a lightning rod.
  • You bleed off the charge, lightning doesn't strike.
  • Your neighbor doesn't have a lightning rod.
  • They get fried.
  • You're fine. They're not.
  • You're fine. They're not.
  • So, that's a little bit about charges and electricity and, again, it's why our machine works in the first place.
  • Our machine...

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Description

What happens if a person touches 200,000 volts? Should a person even be touching 200,000 volts in the first place? Find out in this live Van de Graaff generator experiment!

Other segments from this presentation are available!

- Liquid Nitrogen and Fire! - /watch?v=ANdt8LuPaEg
- Liquid Nitrogen and the Tea Kettle Mystery - /watch?v=L0q3uWuqjYE

A more complete liquid nitrogen show, shot during one of Jefferson Lab's Open Houses, can be seen here:

- Liquid Nitrogen Show! - /watch?v=enEtTV-FyCU

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