Hi! I'm going to show you how to make an electroscope out of various
bits and pieces that you can find around the house.
This is a glass jar.
I have 2 little pieces of aluminum foil that I cut the same way
into little round shapes like this.
And I put a little hole in one end right here.
So 2 of those... 1, 2.
Some copper wire. This is 14 gauge (AWG),
the thicker the better.
This seems to work fine. I've soldered this end right here and I've soldered this end right here.
That's just to get rid of the sharp edges.
And then I
spiralled this end right here like this, just to make a large surface area. I'll show you
why we do that in a minute.
Just some black tape right here...
electrical tape. And right here this is actually taken from a lid
like this. This is a container from a health food store. It's a plastic lid. So any piece of plastic will do.
I've taken a plastic tube
and shoved it through the lid
and hot glued it right here so it's solid with the lid. A piece of straw will do. This
is some tube that I got from a hobby shop.
Okay, now to assemble it. The first thing I'll do is take the copper wire
and stick it through the tube here.
One thing that you'll have to make sure of is that it'll fit through the tube.
There we go.
That should be a good distance right there.
And at this end right here, just form it into a little hook.
Make it into a little round hook like that.
Then I'll take one peice of aluminum foil
and I'll put it on the hook. Remember, I've made a little hole in one side here so
just carefully slip it on there.
Take the other piece of aluminum foil, it doesn't matter which side's shiny and which
side's flat,
and carefully put that through without breaking the hole.
Smooth them out.
You can see that they're now touching together at the end of the hook.
I have some black electoral tape which I've already cut and put on here.
I'll take the jar now,
slip this over the top,
bend down the electrical tape,
and I'll take this last piece electrical tape
just to reinforce the other tape to make sure that is holds on
well
and last a good, long time.
And just for
convenience sake I'll just bend this
down right here
like that. It's easy to use that way.
And it's done!
Okay, now the next step is to test it.
That's what this piece of vinyl is for. It's just a piece of vinyl that's taken from
window blinds.
Watch what happens down here
when I move this piece close to this edge.
Watch what happens to the aluminum.
You can see the aluminum spreads apart.
Let's take something a little better. Here I have an old vinyl record. That should have a bigger charge on it.
There you go. You can see the two pieces of aluminum foil really spread apart.
So it works. Now my favorite question, why does it work?
The reason it works is
when you rub
your hand against a piece of vinyl like this,
electrons from your hand are transferred to the vinyl.
You can't just touch it. You actually have to have physical motion like that.
Rubbing.
Because the electrons are going to the vinyl, the vinyl becomes more negative
and your
hand becomes more positive.
When you move the vinyl close to the electroscope,
the big surface here,
... get a good charge on there...
Because there's a lot of electrons right here, it's more negative than
positive,
that causes the electrons that are on this piece of copper to move down the
copper, away from the electrons that are on the vinyl. Like-charges repel
each other so if we have a negative charge here, that's going to repel electrons, which are
negatively charged here, down into the jar to the hook and then to the almunium foil.
Now both pieces of aluminum foil are going to become negatively charged. Both of them.
And negative charges repel negative charges. So the aluminum foils
repel each other.
And that's how it works.
Your air has to be very dry in order for this to work.
I've had an air conditioner running, so my air is dry.