Electricity and Electric Circuits

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Mr. Andersen introduces the topic of electricity. He differentiates between static electricity and current electricity. An introduction to electric circuits is also included.
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Transcript Provided by YouTube:

00:04
Hi. It’s Mr. Andersen and today I’m going to be talking about electricity
00:08
and electric circuits. Scientists have known about electricity for a long time. In fact
00:13
the word actually comes from the word amber. Because they realized that you could rub amber,
00:18
which is essentially dried out sap with fur and you could generate a static charge. If
00:23
you’ve ever gone down one of these new plastic slides, you’ve come out with a lot of static
00:28
electricity. And what is static electricity? Well let me show you. Here I’ve got a, I don’t
00:33
have a balloon but I have a rubber glove. And so I’ve blown it up. And if I rub this
00:38
on my head over and over and over you can actually start to hear static electricity
00:43
building up. And what it’s doing is it’s actually pulling electrons off of my hair. And it’s
00:50
putting those electrons on this balloon. What’s left in my hair? Well there’s less electrons.
00:56
And so my hair now has a positive charge. And this has a negative charge. But it’s not
01:00
going anywhere. It’s sitting there so we call that static electricity. And so the reason
01:05
that this kids hair is standing up on end is that all of these strands have positive
01:09
charges on it because they’re missing their electrons. And like charges repel. So they’re
01:14
all pushing on each other. And that’s why they’re all pulled apart. That’s why you could
01:17
touch the end and get a shock. What is that? It’s simply a flow of electrons. And so static
01:22
electricity is where it stays in one place. But the real revolution took place when we
01:26
could actually make circuits and we could control and use that electricity to do things.
01:31
Before that it was mostly steam power. And once we had the arrival of electricity then
01:37
we really had the next revolution or this digital revolution. You probably don’t think
01:42
about it all the time but our whole society now is run by electricity. So if you search
01:47
something in Google, you don’t realize this, but you’re consuming energy at that point.
01:52
Because you’re making a search and so Google has to go search through their database for
01:56
that quote unquote answer. And so they use a huge amount of energy. It’s one of their
02:01
big costs. And so they try and make their data centers as efficient as they can. They’l
02:04
try to put them towards areas where they can get cheap and available energy. So how does
02:10
electricity work? Well this is not a great analogy but it’s an analogy that works fairly
02:15
well. And I stick with it. And so if we have a battery like this. How does that store energy?
02:22
Well a way to think about it would be the same way that we store and move water around.
02:27
And so this is a giant water tower in Finland. And so if we break apart how that works, they
02:32
have underneath the ground they have a pump. And that pump pumps water all the way up into
02:38
the top. And that water is just sitting there. And so that water sitting there has a certain
02:42
amount of potential energy. And in a battery the electrons have an amount of potential
02:47
energy as well. And so we call that push or that stored energy a voltage. Okay. So let’s
02:53
say I want to use some of that. Let’s say I turn my faucet on here in my house or I
02:58
flush the toilet here in my house, well we’ve got all that energy and so it’s going to flow
03:03
in this direction. And so the flow of water through this water circuit is similar to the
03:07
flow of electrons in an electric circuit. Now this diagram is not quite complete. Because
03:12
what happens after that water is done? Well we first of all have to clean it. But after
03:17
we’ve done that it goes right back here so that we can pump it up again. And if there’s
03:22
any break in that circuit we call that an open circuit. This whole system wouldn’t work.
03:27
And likewise if we ever have a break in an electric circuit, we can’t move that electricity
03:32
as well. And so today I just briefly want to talk about simple electric circuits. And
03:36
show you how electric diagrams work. There are a few symbols that you should know. The
03:42
first one is the idea of a battery. On a battery there’s going to be a positive side. And so
03:48
on this battery right here the positive side is going to have that little bump on it. And
03:52
then it’s going to have a negative side. And so the symbol in an electric circuit for a
03:56
battery, we’re going to have a top and then we’re going to have a bottom like that. And
04:03
then it’s going to be connected with lead or wires that go out the other side. And so
04:07
this is the symbol for a battery. And on a battery this is the positive end. So the wider
04:12
side is going to be the positive end. And then this would be the negative end. Okay.
04:16
What about a wire? Well a wire is really simple. A wire is simply going to be a line in a circuit.
04:21
Let me try to make it a little straighter than that. Sometimes lines will pass each
04:26
other. And so we want to make sure we understand if those wires are connected or not. And so
04:32
we usually put a dot here that represents that those two wires are connected. And so
04:37
this right here would be two wires connected. So electricity could flow through it. But
04:41
if you just have wires crossing each other inadvertently we don’t usually don’t draw
04:45
that dot to connect them. Okay. Next thing. There are things that actually slow down the
04:50
movement of electricity and we call those resistors. And here are some resistors right
04:54
here. I’ll talk in a little bit more detail later. You can actually look at the color
04:58
bands on it. And you can tell how much resistance there is. But a resistor is going to be anything
05:03
that slows down the movement of those electrons. Or impedes their movement. And so the symbol
05:10
for a resistor is this. It’s just up and down lines. And then we have leads on either side.
05:17
Okay. Next we have a light bulb. A light bulb is connected. So you can actually see that
05:22
electricity will flow in the bottom. So there’s a little bit of metal on the bottom. And then
05:26
it’s going to flow out on the side. And so it’s connected all the way through the lightbulb
05:31
through a filament. And then it goes all the way down to the bottom. And so the wire goes
05:35
through it. It’s high resistance wire that goes through right here. And so it gives off
05:39
a lot of heat and light. And so the way that I’ll draw a light bulb to show that it’s connected
05:45
all the way through is to draw a loop. And then I draw the bulb around the outside. Next
05:51
we’ve got a switch. A switch is simply an opening in the circuit. And so this would
05:55
be like a light switch. And so a light switch is drawn like this. We just have a switch
05:59
like that. And then if it was a closed switch, we would just have it like this. And so this
06:08
would be an opened switch. I’ll try to make that a little straighter. And this would be
06:12
a closed switch right here. So electricity can flow here. But it couldn’t flow through
06:19
here. And the reason it can’t flow through here is that water or excuse me, electricity
06:24
is not able to move through the air. And so we almost call that an infinite amount of
06:28
resistance. And then the last thing we have is a potentiometer. So I said that wrong but
06:34
a potentiometer works like this. We’ve got a variable amount of resistance. And so we’ve
06:41
got an arrow. And then we’ve got a wire going out the other direction like that. And so
06:47
electrify comes through this direction. And then it goes out this direction. But we can
06:50
move this back and forth. So we can vary the amount of electricity that moves through it.
06:55
If you’ve ever used a dimmer switch in your house you’ve seens that a dimmer switch just
06:59
looks like this. So how does that work? We’re turning the amount of electricity that can
07:03
move through the potentiometer and so we’re letting either more electricity or current
07:08
flow or less. And so we can get more light or less. So those are the circuits. Now all
07:13
I want to do is just do a little bit of practice. And I’ve got some pictures here. I think I’ve
07:18
got just three of them. So if you want to pause and then try to sketch out what that
07:22
circuit would look like, you could do that. So here we’ve got a simple battery. And then
07:28
we’ve got a light bulb. So if I were to draw this, I tend to draw my circuits on the left
07:32
side or my batteries on the left side. So I’m going to draw my battery first. So this
07:39
right here is the positive end. And so I’m going to draw my battery like that. Now I’m
07:43
boing to draw a light bulb. And then it’s going to go right back to the battery. And
07:48
then we put a bulb on it like that. And so this is what the electric circuit would look
07:56
like. It’s simply has a battery here. So this would be the positive end and then this is
08:00
going to be the negative end. Electricity is going to flow through this loop and it’s
08:05
going to light the bulb. And that’s a closed circuit because it goes all the way in a loop.
08:09
And so it can return. Next one. If we try this. This gets a little bit more complex.
08:16
We’ve got a battery. And then we’ve got a series of lights. So let’s try that. I’m going
08:22
to draw my battery here on the side. So this is my battery. And I like to kind of make
08:28
this as simple as I can. So this is a wire here. A wire here. And a wire here. And so
08:33
what we have is three loops. And so I’m going to draw one loop, so I’m going to go from
08:38
the top to the bottom. And so this would be my first loop. That’s got a switch that’s
08:44
actually closed. So I’m going to draw it like that. It then has a light bulb. And then it
08:52
goes back to the battery. My next loop over here. We’ve got the same thing. So it’s got
08:58
a switch. It goes through the light bulb. And then it goes back. And then we’ve got
09:07
my third loop. So my third loop goes like this. It’s got an open switch. It’s got a
09:14
light bulb. And then it’s going to go back to the battery. And so this would be a circuit
09:21
diagram for that. Electricity can go all the way around. There’s actually three pathways
09:27
that it can go. You can see right here that since it’s open, so since we’ve got an open
09:33
loop right here, electricity can’t go through that. So we can’t have electricity going through
09:37
here. So we call that a high amount of resistance. So where’s the electricity have to go? It
09:42
has to go through the other loops. And so let’s go look if that’s right. Yep. You can
09:45
see that these two lights are lit because electricity is going to move through it. But
09:49
no electricity can pass through here. So there’s no light on at that point. But we have a continuous
09:54
loop to this. And a continuous loop to that. Okay. Let’s do the last one. Last one. This
10:02
is a picture of the Arduinos which we are actually going to use in class. This has a
10:10
processor over here on the side. It’s got electricity coming out of here. This would
10:16
be the positive end. And then this is going to be the negative end. This is called a breadboard.
10:21
And so the way breadboards are connected is that there are connections horizontally. So
10:25
there’s a wire that connects all of these lines. And then on the side there’s going
10:29
to be a wire that connects them all vertically. And so there’s a wire connecting through there.
10:34
And so that maybe helps to trace it. I’m going to start by drawing my battery again. So we’ve
10:39
got our battery here. I’m going to go from the negative side. So I’m going to go from
10:42
this negative side. So you can see right here it’s going to connect to a light bulb. So
10:47
I’m going to do that first. So we’ve got a light bulb. I’ll try to make that light bulb
10:52
a little bit bigger. So now we have a light bulb. You can see that that goes through the
10:57
light bulb. It goes down to the next level where we’ve got a resistor. So my resistor
11:03
is going to look like this. Like that. And then it’s looks like the next thing we have
11:11
is a potentiometer. And so if I go like that it’s going to be a variable resistor. So it’s
11:17
going to be a variable resistor. And then we’ve got the other side with that arrow.
11:24
And then it’s going to connect back to my battery. So how does this circuit work? Well
11:30
you can vary the amount of resistance here. And so I would imagine in this circuit when
11:35
you turn this dial back and forth, it’s going to vary the amount of electricity. And so
11:39
this light is either going to get bright or it’s going to get very dim. And this resistor
11:43
right here is probably the role of that is to decrease the amount of current so that
11:48
we don’t have too much electricity going through the light bulb. And so that would be the circuit
11:51
diagram for that. So again electricity is simply the movement of electrons. And in the
11:56
next few podcasts I’m going to talk in a little bit more detail about what is voltage, what
12:00
is resistance, what is current. How do we quantify all of those things. But the first
12:04
thing you should understand is that electricity has to have a loop. It has to make it all
12:09
the way back. If it’s not and it’s just sitting there, it’s static electricity. Like in this
12:14
balloon. Like in my hair. And like in lightning as well. So I hope that’s helpful.