Hey, I'm David from the Ontario Science Centre and today I'll show you some cool
tricks you can try at home use it static electricity. Here's another challenge you
can try at home. See if you can move a pop-can off of the table without
touching it. Go ahead pause here and give it a try.
All matter, from basketballs to books, is made up of charges: positive protons
and negative electrons. When you rub two different materials together, like say
cotton and rubber, electrons from one will get transferred
to the other, building up the static charge and we call this charging by
friction. Once you've generated a static charge, you can use it to do a whole
bunch of things, like move a can without even touching it.
These challenges are a lot more challenging if you try them yourself.
When I tried that last challenge at my house I ended up using a rubber balloon
and a cotton towel, but honestly I have no idea what materials you have at your
place, so try a bunch of different things. Do metal and styrofoam, do fleece and glass, even do plastic and cat fur. Some combinations work great, others not so
much. Find whatever combination works best for
you. Don't worry, I'll wait.
Oh, welcome back. Now that you've perfected your charging technique, you
can challenge your family and friends. When I'm at the Ontario Science Centre,
we have a huge static electricity generator to make people's hair stand up.
Here at home this is the best I can do.
This balloon is made of rubber, which means it's good for rubbing. It's also
good at taking and holding onto electrons. When I rub the balloon on my
head, electrons are transferred from my hair to the balloon. These extra negative
charges give the balloon an overall negative charge and because my hair lost
some of its negative electrons it's left with a positive charge. As you can see,
the negative charge on the balloon and the positive charge on my hair are
attracted to each other, or you could say opposite charges
attract. Here's another challenge you can try with your family. See if you can
balance a plate on top of a cup. Seems easy, right? There, no problem. But what
if I charge them first. The plate and the cup, they're made of the same material,
polystyrene or styrofoam, which means when I rub them on the same thing, this
case my hair, they should pick up the same charge and as we will see things
with the same charge repel each other. We've seen that opposite charges attract
and like charges repel, but what happens when you have a charged object and a
neutral one. Welcome to my bathroom. This water is statically neutral because, try
as I might, it just can't seem to charge it by friction. What do you think will
happen when I bring a negatively charged hairbrush near the neutral water? I'll
wash my hands while I let you think about it.
Happy birthday to you, happy birthday to you, happy birthday
dear Science Centre. As you can see, the neutral water is attracted to the
negatively charged airbrush. Is that what you guessed?
We actually saw the same effect before when I moved the pop can with the balloon.
The water contains roughly the same number of positive charges as negative
charges making it neutral overall. When I bring the negatively charged hairbrush
near the water, the electrons are repelled, leaving a positive region near
the brush. The positive charges in the water are then attracted to the negative
hair brush, causing the stream to bend. The negatively charged hairbrush
repelled the water's electrons and bent the stream towards it, but what would
happen with a positively charged object. The glass has a pretty weak hold on its
electrons, so when you rub it on something like silk or polyester, it will
give up its electrons leaving it with a positive charge. You may have noticed by
now that it always seems to be the electrons that move around and never the
positive protons. That's because electrons are about a thousand times
smaller than protons and they're in shells on the outside of the atom making
it easier for them to move around and transfer between materials. That's
probably why it's called electricity and not protonicity. If the negative hairbrush
bent the water what will the positive glass bottle do? I'm not going to show
you the answer to this one, you'll have to try it in your own bathroom.
Now that I've shown you how to charge an object, I guess I should show you how to
discharge them too. After all, I don't want you stuck like this forever. Objects
are naturally neutral with the same number of positive and negative charges.
When an object has more of one than the other,
we say that it's charged. The hairbrush has more negative charges than positive
ones, while the bottle has more positive the negative. To discharge them, we need
something really big, with so many charges that it's able to accept a few
extra, while also giving up some of its own. For that we use the ground, because
it's pretty much the biggest thing on earth and we call it grounding because
scientists aren't always very creative with their names. When I rub a balloon on
my head, my hair develops a positive charge. To get back to neutral,
I need some negative charges from the ground. I can do this by touching
something connected to the ground, like this metal tap and my hair should fall
back down to normal of course you can also discharge yourself by touching
someone who's touching the ground. Ow! Just don't be surprised when they get
annoyed with you. Today we used friction to charge objects,
saw that opposite charges attract while like charges repel and grounded
ourselves back to neutral. Watching this video is a start. The next step is to try
some of these static tricks for yourself.