How to make an electroscope (DIY)

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.