Hi! After the pain-staking process of
pain-staking...pains-taking
Fine! After the pains-taking process of explaining and putting the Van de Graaff machine together in my last video.
I can freely experiment with it now.
Basically this machine creates super high DC voltages that's charged in its capacitance.
Which is basically between its top dome and the earth or surrounding conductors or this ground ball for example.
I'm holding the ground ball in one hand and from the size of the arcs...jump (ouch)...from... over
(OWW)
four inches away
I can say that the voltage of the dome can be over
200
Ouch!
thousand volts
and that's just the voltage when it
SH@#!...oww!
Guess it's a capacitor and can hold charge for a while
If the tower was taller and further from any conductor and in vacuum, the voltage would rise much higher
But with the belt constantly putting charge in the dome you would expect the voltage to keep climbing, but that's not true
See, at any voltage - even one volt - charges to start to fly off a charged surface into air molecules or just as single electrons
But at higher voltages much more charges run away and leak due to the stronger repelling force between similar charges
so the voltage can only rise to a point where the amount of charges running away
is equal to the amount of charges being put in by the belt.
And the charges
accumulate much more in sharp edges like this nail and run away much faster from it
creating a wind like this.
Although it seems like half of the flame is getting attracted to the nail and the other half is being pushed away
Well a flame is the plasma or ionized gas
Which means is positively AND negatively charged
so some of them get attracted and some of them repelled from the point
Well, this napkin shows the charged wind better
in any case
having a spike or sharp edge result in
charges running away and so the voltage drops
and that's why the arcs are much smaller now
and that's why we try to avoid sharp edges in the dome
Similarly, if I bring a sharp object close
it quickly sucks away the charges from the dome without any visible arch
Although, in the dark, you might see some glow on the tip.
The voltage significantly drops and that's why you don't see any discharges between the gap
This is how lightning rods attract the charges toward themselves and prevent them from jumping elsewhere
You saw me in much pain when I was struck with only five kilo-volt in my Leyden jar video
Aaouuw!
Shii...**BEEP**
Oww!
So, why is it that I don't get hurt as much
being zapped by hundred to two hundred kilo-volts?
If electricity is flowing through me, why am I not dead?
It is really the current that gets you
and
not really the voltage.
NOOO!
Now then..
Besides that it's a pretty good presentation though
Go watch it, link in the description.
The current through my body would be very high, if my body resistance is around five
kilo-ohms under high voltage for two hundred kilo-volts
There would be a 40 amp
spike of current through my body.
See when the capacitance of the machine shorts to my body through the arc
The entire voltage of the capacitance falls across my body
But it drops quickly to zero with a time constant of R times C
and for the same reason, there will be a huge spike of current that quickly goes away.
But why do I say 5 kilo-ohm of body resistance only?
When we measure it using a meter we read somewhere around hundred kilo-ohm to a mega-ohm
The reason is that most of the body resistance is made of the thin dry skin
As you have seen, high voltage has no problem breaking through inches of air
so thin dry skin is like a bad joke against high voltage
The arcs short from the dome directly
to the low resistance tissue under the skin and spread through the body
If I measure the capacitance between the two domes
with the zero of my meter being around twenty to thirty Picofarad
I'll see an increase of 10 to 20 Picofarad
so let's say there is 15 Picofarad between them and my Leyden jars capacitance
I measured was around one-and-a-half nanofarads
So here the capacity is hundred times smaller than the Leyden jar which means those large arcs, although they might contain more energy
they discharge hundred times faster.
So I don't feel as much pain as I do from the Leyden jar.
Of course, it doesn't mean it's not damaging. My skin is already getting red and I can see some burn spots
It's like their stuff. They use for hair removal, of course all this is like kids play for me because I've seen worse
Now if I hang a piece of paper from this string and bring it close
Shii!...**BEEP**
Oww!
You see the ball keeps
bouncing between the two domes because it is neutral at the beginning and gets attracted to the big dome fix up the same charge and
Gets repelled to the ground dome where it becomes neutral and it goes back and forth
Something starts to smell around here
The top dome keeps its charge until a pointy object gets too close
Which reminds me, i taped a wire to the center contact of my Leyden jar with the end strands poking out and I connected the outer
Contact to ground and brought another wire from the outer
Contact close to the center contact with a centimeter gap
So if the voltage on the jar is too much there will be an arc between them
Let's leave it on the table and see what happens
It seems like it's wirelessly being charged
Although it's not Wireless our wire here is air because the charges from the dome are
Directed right through the air to the spiky wire than charging the capacitor
OAUW! SHI..*BEEP*
Seems like the capacitor wasn't the only thing being charged my floating body being too close to the dome was charging too now
Of course, we have the obligatory
Hair-raising tests, but unfortunately, I don't have much to offer. So I guess we will be using electroCUTE
Where is she? Now we have electroCUTE
Charging up it's slowly going up
Very nice
Remove your hand and put your foot on the ground suddenly
She is discharged
Let's touch fingers
OOW!
That was strong
Hey, I may not have much hair on my head to offer. *Ouch*
But I have a whole bunch of
glorious knuckle hair to offer. *Ouch*
You see my hair rises when I bring my grounded body close and the voltage of the dome rises. *Ouch*
But when there is a discharge.*Ouch*
The voltage of the dome drops and so the attraction goes away and my *Ouch* hair drops back to zero
So the dome might be originally at 300 or 400 thousand volts
But as I bring my hand close it sucks the charges from the dome and the voltage of the dome dro*Ouch*
drops
Lower and lower and *Ouch* at this point
The voltage across it is 0 because the amount of available charges is so low that even my body can short it out
now for my last trick I have this cupcake paper cups that if I put on top of the dome
flat face up
They fly away like this
But the interesting thing is that if I put them
flat face down
They get *Ouch*
attracted to the dome
And there are no arcs isn't that amazing I give you three monetized seconds to figure out why
The reason is that the edge of the paper is good at getting rid of the charges and so it can attract more
Charges in and the top dome keeps attracting them the voltage of the top dome drops and that's why you don't see any arcs there
but if I *Ouch*
Put the paper
flat face up
the flat face is not good at
Getting rid of the charges so it gets overcharged and it out flies away
Oh, by the way when you see the ground ball is bouncing back and forth it's not because the arcs have some special force
It's because when the two domes are charged oppositely they get attracted to each other and the ground dome leans
Towards the big dome and when there is a discharge that attraction goes away because the charges go away and the dome just falls back
The amount of noise this damn motor is making is
Awfully high if you want to make it make it with an AC motor
And I suppose you can add a dimmer to adjust the speed if needed
See ya
(UNIBROW DANCE)