so today we are gonna learn about
electrostatic shielding and Faraday
cages and why it's not such a bad thing
if you're in a lightning storm as long
as you're inside a car and I don't want
to do that with me so we're gonna do
with then June here we have Benjamin
Franklin wearing a nice little Hawaiian
hula skirt made of tinsel and he is
about to be in a thunderstorm we are
going to make our thunderstorm with our
Van de Graaff generator you can think of
the belt in the Van de Graaff generator
going around like this as analogous to
the air circulation underneath the
Thunder head as the Thunder head builds
up and then you can think of this up
here is the analog of the cloud so soon
as i ungrounded art charging up and you
see mr. franklin they're getting a
little bit uncomfortable you see his
hula skirt streaming out behind him as
he is in right now in quite a large
electric field and as you can get a
sense there he's not so happy at this
point maybe I'll turn it up even higher
there you see well I've got a lightning
bolt going to my grounding rod and as
you can look at what's happening to
Benjamin as the lightning bolt hits the
grounding rod there you go Benjamin is
not happy so now what we're gonna do is
we are going to have the same
thunderstorm the same electric field but
we are gonna put Benjamin in a Faraday
cage so to put him in the cage I'm going
to start by turning this off and we'll
ground him and here's my Faraday cage
right here I'm gonna put Benjamin in the
cage there we go okay Benjamin's gonna
be in the same spot that he was before
same tinsel skirt that he has but had
before but this time he is in a cage
like for example if you're in a
thunderstorm but you are safely in a car
so let's see whether it is indeed safe
and here we go let's turn on the Thunder
or the Lightning rather let's turn on
the lightning
now if you look you can see that there's
lightning hitting the cage there is that
lightning bolt going from the
vandegraaff right to the cage here and
you can see that the cage has a very
considerable electric field on it by
looking at the tinsel over here on the
far side which is streaming out behind
it just like the tinsel on Benjamin was
before but now I'll look inside at
Benjamin in there and I have to be
careful not to touch the cage but now
look inside at Benjamin in there and his
tinsel is completely motionless Benjamin
is completely comfortable in there calm
at rest while the lightning storm rages
around him literally around him and I
just got me if I touch that I get
shocked ok that's what that's what I
just got shocked but Benjamin is
completely safe this is the phenomenon
of electrostatic shielding and this kind
of a cage is often called a Faraday cage
and will now turn the Lightning off
