Physics: Electrical Charge Transfer

What is electrical charge transfer? Y'know that shock you get shuffling your feet along the carpet and then touching an electrical socket? Yeah, don't do that.

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Transcript

00:31

watch this video right here. Without electricity we'd probably be

00:35

broadcasting this physics lesson via, smoke signals. All right well what is

00:39

electricity anyway? Don't worry we're not gonna go all the way back to Ben [Ben Franklin flying kite in storm]

00:43

Franklin flying a kite in a storm or anything. But, we need to understand

00:47

what's actually going on when you plug in your hairdryer. I mean we know that

00:51

the end result will be incredible sexiness. But, how does electricity move

00:55

from the wall, to that wire, to the actual motor, fan thingy, there. Well let's take a

01:00

look at an atom. We'll go super basic, the hydrogen atom. Almost all hydrogen has

01:05

one proton and one electron. Well the proton has a positive charge, it's all [hydrogen atom drawing]

01:09

about smiles and motivational posters and the electron here is a real debbie

01:14

downer, because well it has a negative charge. That positive and negative

01:18

difference is called polarity. And the amount of charge in a proton and in an

01:22

electron is equal, even though their polarity is opposite. That amount is

01:26

called the elementary charge. You can't get any smaller than the elementary

01:31

charge and that's as low as it goes. There's never going to be a time when

01:34

just half an electron shows up, or where we'll have to deal with one quarter

01:38

proton. The elementary charge is written as just a little e, like that.[atom with e above] These

01:43

electrical charges either positive or negative are fundamental properties of

01:47

matter, kind of like mass. And you might be wondering where does charge really

01:51

come from and yeah that's a really good question. I hope you come up with an

01:54

answer soon because so far science doesn't have a good explanation. There

01:58

are some ideas out there that are pretty complicated and involve mind-bending

02:02

aspects of quantum mechanics and honestly, just thinking about that stuff [construction man wearing helmet]

02:06

makes me want to find a darkroom and rock gently back and forth. So we're not

02:09

gonna dig into that right now. And just like mass charge is conserved,

02:13

meaning it can't just disappear. It can move from one object to another,

02:17

but, you can't spontaneously create a charge out of thin air.

02:21

Now in our hydrogen atom here, we've got one negative particle and one positive

02:25

one. Everything is nice and balanced, that's not always case. Some molecules

02:30

have more protons than electrons. And well you know vice versa. It's pretty [two atoms working next to each other]

02:34

common for electrons to only be loosely attached to the nucleus of an atom. They

02:39

don't want to get tied down, so they're playing the field.

02:42

Well these electrons can become completely free, just waiting for some

02:46

new positively charged atom to come and sweep them off their feet. And it would

02:50

have to be a positively charged atom, because like charges repel and opposite

02:55

charges attract. It's like magnets, in fact it is magnets.[red magnet]

02:59

Electricity and magnetism are closely related. So closely related in fact, that

03:03

there's a whole field of study, within physics, called electromagnetism. Magnets

03:08

have two poles, one positive and one negative, one north and one south. Maybe

03:12

you've tried to push the positive poles of two magnets together and felt a

03:15

strong resistance pushing your hands back. It's the whole like charges repel

03:20

thing. And of course if you bring the positive side of a magnet, near the

03:24

negative side of a different magnet, you're gonna have an instant attraction.[boy and girl holding magnets]

03:27

All right you guys get a room. Any particle that has an electric charge,

03:30

creates an electric field. An electric fields can be a little bit tricky

03:35

because we can't see them. It's a lot easier to do physics with things you can

03:38

actually look at. But electromagnetic fields are similar to gravitational

03:41

fields. They do their work without requiring any movement from their source.

03:45

If I want to make something move, I have to go over and make contact with it. So

03:48

if a Girl Scout comes to my front door trying to sell me cookies, I have to make[girl scout at door]

03:52

direct contact with the door to slam it in her face. Sorry, but, Thin Mints are

03:57

addictive and I don't need to go down that road again. But an electromagnetic

04:01

field, can push, or pull, something towards an object, without any contact at all.

04:05

We're gonna prove this in just a minute. There's another way gravity and

04:08

electricity are similar. They can both create potential energy. Gravitational

04:13

potential energy is created when something is lifted off the ground. If I

04:17

pick up a hammer, gravitational potential energy is stored, because the Earth's [man holding hammer]

04:21

gravitational field is pulling on that hammer. You've learned that the hard way, if

04:25

you've ever accidentally dropped a hammer on your toesies. Result? Potential

04:29

energy, is converted into kinetic energy. It also results in the chemical

04:33

energy in my body, being converted to sound energy, as I scream like a baby.

04:38

With electricity, we have both electric potential and electric potential energy.

04:43

Yep they're very similar sounding, but no, they're not the same thing.

04:46

Electrical potential, is also called electrical potential difference. You can

04:51

also call it voltage, which you've probably heard before. Electrical [chalkboard with facts]

04:55

potential, is the potential energy that a theoretical charge would have, if placed

04:59

in an existing field and it's what causes electricity, to go from point A, to

05:04

point B, in a circuit. Electoral potential energy, is potential energy to charge

05:08

your concern with, actually possesses. That might sound confusing, but

05:12

electrical potential and electoral potential energy, will be the topic of a

05:15

future video with equations and all sorts fun stuff. So, you know, don't sweat

05:19

it for now. Nope, right now we're gonna go to the

05:21

experiment with electricity. Normally I'd recommend leaving electricity to the

05:25

professionals, like me. You shouldn't be messing around too much with electrical

05:29

stuff. Because well, it doesn't always end well and no one likes the smell of [2 boys in school lab]

05:33

burning hair. But in this case all we need is some tape, scotch tape, to be

05:36

precise. Yeah there aren't gonna be bolts of electricity flying around, but this is

05:40

still gonna be pretty cool. We need four strips of tape, each about five inches

05:43

long. That's about 12 centimeters, if you don't speak, you know, American. Fold over

05:48

a little bit at one end, so you've got a non sticky handle to work with. Okay now

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take two strips of tape. We'll get super creative and call them piece 1 and piece

05:55

2. Stick them to your desk, or your table, or countertop, or whatever and pull [2 pieces of tape]

05:59

each piece off of your chosen surface and keep them separated. Alright, job calls for

06:03

two hands people. Okay now bring the non sticky sides, of each piece of tape,

06:08

toward each other. The two pieces should repel each other just like that. Now

06:12

bring one of the pieces near your hand, it should be attracted to you and of

06:15

course it is. You're a total hottie right. But it's also due to electric charge.

06:19

When you stick tape to your desk, it actually forms molecular bonds and when

06:24

you pull the tape off those molecular bonds are broken and some electrons come

06:28

along for the ride. Yeah, who know that, when you use scotch tape you're actually

06:32

splitting up molecules. It's not quite the reaction you get from splitting atoms, and

06:37

no that's a good thing. [nuclear bomb going off] Crafting should never go nuclear. All

06:40

right well since there are extra electrons, sticking to the tape, well it

06:43

now has a negative charge. And since we did the same thing with each piece, they

06:47

both have the same kind of charge. Like charges repel, so they don't want

06:51

anything to do with each other. But you and your hand? Well turns out your, a ray

06:55

of positivity, in this cruel world, so the tape wants to snuggle up with you. [hand attracting tape]

07:00

Because opposite charges attract. All right, now let's play with last two

07:04

pieces of tape. Keeping with our awesome naming system, we'll call them

07:08

3 and 4. Stick piece 3, to the non sticky side a piece 4. Before you pull them

07:14

apart, you should know, that we're gonna be doing the same kind of thing. Holding

07:17

the pieces close to each other and seeing what happens. All right any

07:20

guesses? Will they repel each other, maybe attract each other, or maybe they'll just

07:24

chill out and do nothing and this whole experiment will be a bust. Okay let's get

07:28

to it. Pull piece three off piece four and hold

07:30

them close to each other. Aw, now we've got attraction going on. In this case where [2 pieces of tape connecting]

07:35

we had some hot tape, on tape action, piece three snagged some electrons from

07:39

piece 4. Which means piece 3 is negatively charged and piece 4 is given

07:44

off positive vibrations. Because well it lost electrons, giving it an imbalance of

07:49

protons. When we've got opposite charges, we've got attraction. This experiments an

07:55

example of static electricity. Static electricity is an imbalance of charges

07:59

on the surface of an object. That imbalance can build and build, but [chalkboard with facts]

08:02

eventually it will discharge. Alright we've dealt with static electricity

08:07

before, ever grabbed a doorknob and felt a jolt? Well unless your parents have grounded

08:12

you and wired your doorknob, so you can't leave. What you experienced was static

08:16

electricity and static electricity is why you hear a wool sweater crackling on

08:21

a dry winter day. We tend to think of static electricity as a small little zap,

08:26

but it can get huge. In a thunderstorm there are a whole lot of little pieces[thunder cloud with ice]

08:30

of ice moving around in the clouds, bumping into each other and swapping

08:33

electrons. This creates an imbalance of charges and when you get a bunch of

08:37

positively charged particles at the top of a cloud and negatively charged

08:42

particles at the bottom, well then boom, lightning. Same basic thing happens

08:46

between clouds and the ground. It's a huge [thunderstorm] amount of energy, but it's static

08:50

electricity. Just like we created, with the tape experiment. And you can

08:54

weaponize static electricity too. If you've got thick socks and carpet and

08:59

you can shuffle your feet around and build up a static charge. Then find [socks on carpet]

09:03

someone, who's been annoying you and reenact that scene from, Return of the

09:07

Jedi. You know feel the force flow through your fingers and ouch yeah it's

09:11

gonna hurt you too, but at least you're ready for it. That'll teach Bob to stop

09:14

stealing your lunch. When you rub your feet on the carpet you're picking up

09:18

electrons, giving yourself a negative charge. When you touch some filthy lunch

09:22

thief, well those extra electrons go from you to him. [boy shocking other boy]

09:26

It's kind of weird that there are these extra electrons all over the place. We

09:29

tend to think of electrons, as part of atoms and they are. But there are lots of

09:33

them, that are unattached and zooming all over the place and that's why

09:37

electricity is able to move around. An imbalance of charges creates the

09:40

attraction, that those negative electrons, just can't resist. And without

09:44

electricity you wouldn't be able to watch this video or see your friends

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stupid snapchat videos. That she thinks are so funny, or you know, read about politics

09:53

on Twitter. Well maybe this electricity thing isn't so great after all. [man looking at phone]