What is engineering circuit analysis?

Engineering circuit analysis involves evaluating electrical circuits by understanding their components, energy flow, current paths, and their functionality in a practical way.

What topics are covered in this circuit analysis course?

The course covers fundamentals like current, voltage, resistance, circuit analysis techniques, and also practical circuit design.

What math is required for understanding circuit analysis?

Knowing algebra is sufficient to understand circuit analysis, although some calculus and complex numbers will be touched upon later.

What is the difference between DC and AC?

DC (Direct Current) is a steady flow of electricity in one direction, while AC (Alternating Current) changes direction periodically.

What defines a circuit in electrical terms?

A circuit is a closed loop that allows electricity to flow and perform work; if there's a break, no electrical flow occurs.

How do voltage and current differ?

Voltage is the push that causes electric current to flow, whereas current is the movement of electrons within the circuit.

What does resistance do in a circuit?

Resistance measures how much a circuit component opposes current flow, often changing based on the material and size of the conductor.

What is a short circuit?

A short circuit occurs when a low-resistance connection bypasses part of the circuit, leading to excessive current flow.

Why do different materials have different resistances?

Electrical components display different resistances; smaller wires have higher resistance, affecting the circuit flow.

How does this course approach teaching circuit analysis?

It goes into depth about fundamental concepts of electricity in simple terms before delving into circuit complexities.

Lesson 1 - Voltage, Current, Resistance (Engineering Circuit Analysis)

00:41:24

https://www.youtube.com/watch?v=OGa_b26eK2c

Summary

TLDRIn this engineering circuit analysis course introduction, the instructor, an electrical engineer, explains the study of circuits, the flow of electricity, and the fundamental components involved. The course begins with basics before moving to more complex circuit evaluations. Essential concepts like voltage, current, and resistance are explained, emphasizing their role in circuit operation. The instructor clarifies direct current (DC) vs. alternating current (AC) and introduces terms like open and short circuits. The approach focuses on accessibility, making it understandable for both engineering students and enthusiasts with basic algebra knowledge, avoiding intimidation by breaking down complex ideas into simpler ones.

Takeaways

📘 Introduction to circuit analysis by an electrical engineer.
🔧 Focus on understanding electricity and circuit components.
📏 Basics: Voltage, current, and resistance explained.
🔄 DC vs AC: Understanding different types of currents.
🛠️ Practice is essential for mastering circuit analysis.
🔍 Holistic approach to analyzing what happens in circuits.
🔋 Voltage pushes current through a resistance.
⚡ Current is electron flow, critical for circuit functionality.
🔌 Circuits must be closed loops for electricity to flow.
🔍 Understand circuit fundamentals before complex topics.
🔥 Short circuit: Result from unintentional low-resistance paths.
🔋 Discusses applications and practical circuit designs.

Timeline

00:00:00 - 00:05:00
The lecture introduces the basics of circuit analysis for engineering students and enthusiasts, emphasizing the importance of understanding electrical circuits. The instructor is excited and aims to make the complex content accessible. Key components to be studied include basic concepts like voltage, current, and resistance, and how to analyze circuits. The approach will start with fundamentals and progress to more complex ideas, preparing students to tackle real-world circuit analysis.
00:05:00 - 00:10:00
A basic definition of an electric circuit is provided: a circuit is a closed loop that allows electricity to flow. This concept is illustrated using a battery and wire analogy. The concept of electric current is then introduced as the flow of electrons in a circuit, akin to water flowing in a stream. The electrons' movement is critical to circuit functionality, and understanding this flow is foundational for analyzing how circuits work.
00:10:00 - 00:15:00
The discussion continues with an explanation of electric current, emphasizing that electrons move within the circuit, flowing from negative to positive ends. This movement is like a chain reaction at nearly light speed. For engineering purposes, current is often conceptualized as positive charges moving in the opposite direction of electron flow, simplifying calculations and avoiding negative signs in equations.
00:15:00 - 00:20:00
The concept of electric current is explored further with a distinction between electron flow and the convention used in circuit engineering, known as "hole current," which describes positive charge movement opposite to electrons. This convention helps simplify circuit equations. The unit of current is the ampere (amp), measuring charge flow over time. The concept of amps is linked to everyday applications, indicating power levels in electrical devices.
00:20:00 - 00:25:00
The concept of voltage is introduced as the "push" that causes currents to flow, measured in volts. Voltage is crucial for overcoming resistance and enabling current flow in circuits, analogous to air pressure moving through a straw. The potency of voltage relates to its ability to move electrons through conductors. Higher voltage implies more potential for current flow, distinguishing it from current, which is the actual movement of electrons.
00:25:00 - 00:30:00
Resistance is explained as the opposition to current flow in an electrical circuit, measured in ohms. The analogy of blowing air through different sized tubes helps illustrate how resistance affects current flow — the larger the tube, the less resistance. The discussion highlights the importance of resistance in controlling current flow and its role in circuit functionality. Resistance, voltage, and current are interconnected concepts critical for understanding circuitry.
00:30:00 - 00:35:00
Metric prefixes like milli, micro, kilo, and mega are applied to all units (voltage, current, resistance) to accommodate various magnitudes encountered in circuits. The lecture covers the concepts of direct current (DC) and alternating current (AC), explaining their differences, usages, and implications. DC is constant, typically from batteries, while AC varies, like household electricity, highlighting the historical and practical reasons for these differences.
00:35:00 - 00:41:24
The session concludes with definitions of critical terms such as open circuits (breaks in the circuit path) and short circuits (unintended low-resistance paths causing high current flow), both impacting circuit functionality. The importance of understanding these basics is emphasized, laying the groundwork for more advanced topics like circuit components and Ohm's Law, which connects voltage, current, and resistance. Practical applications and the potential for hands-on learning in electronics are also encouraged.

Mind Map

Video Q&A

What is engineering circuit analysis?
Engineering circuit analysis involves evaluating electrical circuits by understanding their components, energy flow, current paths, and their functionality in a practical way.
What topics are covered in this circuit analysis course?
The course covers fundamentals like current, voltage, resistance, circuit analysis techniques, and also practical circuit design.
What math is required for understanding circuit analysis?
Knowing algebra is sufficient to understand circuit analysis, although some calculus and complex numbers will be touched upon later.
What is the difference between DC and AC?
DC (Direct Current) is a steady flow of electricity in one direction, while AC (Alternating Current) changes direction periodically.
What defines a circuit in electrical terms?
A circuit is a closed loop that allows electricity to flow and perform work; if there's a break, no electrical flow occurs.
How do voltage and current differ?
Voltage is the push that causes electric current to flow, whereas current is the movement of electrons within the circuit.
What does resistance do in a circuit?
Resistance measures how much a circuit component opposes current flow, often changing based on the material and size of the conductor.
What is a short circuit?
A short circuit occurs when a low-resistance connection bypasses part of the circuit, leading to excessive current flow.
Why do different materials have different resistances?
Electrical components display different resistances; smaller wires have higher resistance, affecting the circuit flow.
How does this course approach teaching circuit analysis?
It goes into depth about fundamental concepts of electricity in simple terms before delving into circuit complexities.

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Subtitles

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00:00:00
hello and welcome to the engineering
00:00:02
circuit analysis tutor uh I'm very
00:00:05
excited to teach this course because I'm
00:00:07
an electrical engineer myself so I was
00:00:09
always very interested in electricity
00:00:11
and electric circuits uh things like
00:00:13
that so what we're going to do in this
00:00:15
class is exactly what the title is we're
00:00:17
going to learn all about circuits we're
00:00:19
going to learn about electricity we're
00:00:21
going to learn about the components that
00:00:22
go into circuits but mostly what you do
00:00:25
in engineering courses is learn how to
00:00:27
analyze them given a circuit what is
00:00:29
going on where is the current going what
00:00:31
is the purpose of the circuit uh and so
00:00:33
there's a lot of details there and a lot
00:00:35
of techniques that have been developed
00:00:37
over the years to pull those things off
00:00:39
you know 100 years ago circuits and and
00:00:42
all of the things that we take for
00:00:43
granted today would be super theoretical
00:00:45
but they're all basically physics
00:00:47
they're taking energy out of a battery
00:00:48
or energy out of a wall and letting it
00:00:51
run around in a loop and doing some
00:00:53
useful work with it that work might be
00:00:55
spinning a motor right to spin a fan or
00:00:58
that work might be shooting a radio wave
00:01:01
out across the world to talk to somebody
00:01:03
else or that work might be to go into a
00:01:06
microprocessor and you know flip a bunch
00:01:08
of bits around and add a bunch of
00:01:09
numbers together basically create what
00:01:11
we call a computer but there's basically
00:01:14
infinite number of ways that you can
00:01:16
create circuits to do what we want them
00:01:18
to do but before you can understand a
00:01:20
microchip before you can understand an
00:01:21
amplifier before you can understand a
00:01:23
nuclear power plant you have to start at
00:01:25
the basics you have to start at the
00:01:27
really really simple questions the
00:01:29
things that that are so fundamental and
00:01:31
that's what we're going to do in this
00:01:32
course we're going to start with
00:01:33
fundamentals and then we're going to go
00:01:35
on and talk about circuits and the
00:01:36
different kinds of circuits how to
00:01:38
analyze circuits figure out what's
00:01:39
happening in inside these circuits and
00:01:42
you'll find there's a broad array of
00:01:43
tools that you learn in your classes to
00:01:46
help you with that now I'll say right
00:01:48
away the title of this guy is
00:01:49
engineering circuit analysis but my goal
00:01:52
is uh to really try to make it as
00:01:54
accessible as possible to anybody out
00:01:56
here who wants to learn it right uh
00:01:58
don't let the word engineering SK area
00:02:00
too much engineering is a big word makes
00:02:02
it sound really hard but I'm going to
00:02:03
try to break things down uh so that
00:02:05
everyone can get it now I will say the
00:02:07
good news is and this is true with
00:02:10
circuits in general there really aren't
00:02:12
that many uh big picture Concepts to
00:02:15
understand we in this section we're
00:02:17
going to talk about voltage current and
00:02:19
resistance because they're so important
00:02:20
but really once you get past that
00:02:22
there's a few other big picture Concepts
00:02:24
and then you understand really the
00:02:25
basics the challenge with circuits comes
00:02:28
is that I can uh draw a circuit on board
00:02:30
and you might know how to analyze it and
00:02:32
figure out what's going on uh and then I
00:02:34
might change one little line one little
00:02:36
branch of the circuit might completely
00:02:38
change how the thing operates right so
00:02:40
there's an infinite Variety in how they
00:02:41
can be constructed that's what really
00:02:43
requires you to get a lot of practice
00:02:46
and that's what this course is going to
00:02:48
be it's centered around practice
00:02:49
practice practice practice and to be
00:02:51
honest with you you don't need to know
00:02:53
much more than algebra to do very very
00:02:55
well in this class yes we are going to
00:02:57
use complex numbers a little bit later
00:02:59
on on later later in the course not and
00:03:01
not in the beginning we are going to use
00:03:03
uh some calculus some integration later
00:03:05
later later on in the course uh but by
00:03:07
and large you can do a ton of circuit
00:03:09
analysis with just some basic algebra
00:03:12
and that's the way I'm going to try to
00:03:13
teach it to you so that you know
00:03:15
everybody it can be accessible to
00:03:16
everybody while also catering to the
00:03:18
engineering student which is really the
00:03:20
focus of the class all right so I had I
00:03:22
had to figure out where to start I think
00:03:25
the most important thing for everyone
00:03:27
watching this to understand is the
00:03:30
concepts of voltage current and
00:03:33
resistance because those three things
00:03:35
we're going to end up zooming in on and
00:03:37
talking about for the next many many
00:03:40
hours uh and you really have to
00:03:42
understand what they are a lot of
00:03:44
students if they haven't already had an
00:03:45
interest in circuits uh they get very
00:03:47
confused at what the difference between
00:03:49
voltage current is and how does
00:03:51
resistance play into that so what we're
00:03:53
going to do in this particular section
00:03:54
is zoom in on that and I want you to
00:03:56
really make sure you internalize and
00:03:58
understand what they mean because as go
00:03:59
and solve a circuit and I'm asking you
00:04:01
what the voltage is you need to kind of
00:04:03
have a internal picture of what what
00:04:05
that means even before you do any math
00:04:08
so there's no math in this section you
00:04:10
know this is all definitions I try to
00:04:11
make it as interesting as I can but it's
00:04:13
so incredibly important make sure you
00:04:15
understand this first things first I
00:04:18
think we all know this what is an
00:04:20
electric circuit what is a circuit I
00:04:22
mean a lot of people um a lot of people
00:04:26
think they know what a circuit is and
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most people probably do but what is a
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circuit
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uh the simplest one sentence definition
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is it's a
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closed it's a closed
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loop that
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carries what does it carry what do you
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think
00:04:51
electricity you know like I say I have
00:04:53
to start somewhere and start I start I
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never never never assume that you know
00:04:57
anything about what I'm talking about so
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a Circ
00:05:00
uh you think about a circuit of a
00:05:01
racetrack or a circuit an the nd500 it
00:05:04
has to go all the way around if you
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don't have it going all the way back
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around to the starting point then you
00:05:08
don't have a circuit and no electricity
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can flow in such a situation unless it
00:05:13
goes all the way back around to where
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you start from so in order to have a
00:05:17
circuit it has to come back to where it
00:05:18
starts from so a simple example of that
00:05:21
without really getting to any kind of
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detail is um you know here's a source
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I'm going to put a plus minus to
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different to to denote it as a source
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this could a battery you know this could
00:05:31
be a battery that you pull out of you
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know you go buy it at the store and
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we're not going to put anything in the
00:05:35
circuit with it we're just going to draw
00:05:36
these lines here these lines are wires
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so it would be just like you might think
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you get a battery You' hook a wire up
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that goes all the way back around to the
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other side this can completes a circuit
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the electricity can circle around and
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around and around here coming from one
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terminal back around to the other one
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that means it's a
00:05:53
circuit super super important but you
00:05:56
know also very simple as well now let's
00:05:58
get to something that's it's not quite
00:06:00
so simple but you know a lot of people
00:06:01
still May understand this what is
00:06:04
current and when I say current I mean
00:06:07
electric got to learn how to spell
00:06:09
current first of all current electric
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current what is electric current okay
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the simplest definition to write down
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for what electric current is it is the
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flow of
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electrons in a circuit
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it's the flow of electrons in a circuit
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so everybody's heard heard of current
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electric current um an analogy to
00:06:36
electric current would be current in a
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stream we all know what a current is in
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a stream right it's when the stream is
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moving there's a current it's pushing
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your boat right it's the movement of
00:06:46
something don't confuse that because a
00:06:48
lot of people get confused with voltage
00:06:50
and current if you're not really
00:06:51
familiar with these terms voltage has
00:06:54
really nothing to do with anything
00:06:56
moving we'll talk about what voltage is
00:06:57
in a minute the current the electric
00:06:59
current think of a stream think of
00:07:01
something moving that is what's moving
00:07:03
so in real life if you have a piece of
00:07:05
wire which is metal the electrons are
00:07:08
really and truly what's moving around in
00:07:10
that wire so if you wanted to kind of
00:07:12
zoom in and draw a little picture of
00:07:14
that um we could draw another little
00:07:17
circuit here little simple one
00:07:19
anyway like this goes up connect it all
00:07:22
the way back around to the beginning so
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there's going to be current circulating
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around and around and around but if I
00:07:27
zoomed in let's say this is a piece of
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wire right
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if I zoom in this wire and get a
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microscope up on top of it and zoom in
00:07:35
on it really really tight if I could see
00:07:38
that what I would see inside is a bunch
00:07:40
of atoms right so this atom is going to
00:07:43
have a positive nucleus and this atom is
00:07:45
going to have a negative electron
00:07:47
orbiting around this atom now in real
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life this might be you know copper wire
00:07:52
so there'll be lots of protons in the
00:07:53
nucleus and lots of electrons but for
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the purpose of this drawing just pretend
00:07:57
that there's a positive Center and
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there's a NE
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things orbiting now here's another atom
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here it's got a positive Center and it's
00:08:04
got a negative thing orbiting this one's
00:08:06
got a positive and a negative every atom
00:08:08
has this positive Center and negative
00:08:10
surroundings now in metals like copper
00:08:12
and gold and silver that conduct
00:08:13
electricity well these electrons they're
00:08:16
not really tightly held to the atom
00:08:19
they're there but they can be coerced so
00:08:21
to speak to move they can be you know
00:08:24
you can talk them into moving if you if
00:08:25
you try hard enough the object that
00:08:27
actually talks them into moving moving
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is the battery right is the battery or
00:08:33
the source coming from your wall for
00:08:34
instance and when that happens when you
00:08:36
hook a battery up to this wire like this
00:08:39
since these electrons are not really
00:08:41
really held on terribly tightly what
00:08:43
happens is this electron you know down
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here this electron is going to jump
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literally it's going to jump over and
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grab and go into the orbit of the next
00:08:53
atom and at that moment the same time
00:08:55
that happens it's a chain reaction this
00:08:57
guys goes to the next guy this electron
00:09:00
moves to this guy and this electron
00:09:02
moves to its Jason atom and this process
00:09:04
happens at almost at the speed of light
00:09:06
so you can't see this electron movement
00:09:09
but that's what's in fact happening so
00:09:11
it's a chain reaction and they're almost
00:09:12
like in lock step moving from one atom
00:09:15
to the next and this movement is really
00:09:18
you know you can think of it as as
00:09:20
energy of motion is the energy that the
00:09:23
circuit uses to do whatever it's going
00:09:24
to do you know turn a fan turn a light
00:09:26
bulb on whatever that's where the energy
00:09:28
from the battery is going it's going
00:09:29
into pushing these electrons around
00:09:31
which is electric current so when I uh
00:09:35
draw this here I'm drawing these um
00:09:38
these negative electrons moving so this
00:09:41
is what we call
00:09:44
electron
00:09:47
current or electric current there's
00:09:49
another way to say that so the electrons
00:09:52
uh if you want to think of it this way
00:09:53
we'll go draw it down here this is the
00:09:55
negative terminal of the battery this is
00:09:57
where the negative charges are sort of
00:09:58
piled up so here this is called the
00:10:03
electric
00:10:06
current so the electrons literally bleed
00:10:09
out of this negative terminal they go
00:10:10
all the way around and they go back and
00:10:13
they enter it back into the positive
00:10:14
terminal because this is positive so
00:10:16
it's going to attract the negative
00:10:17
electrons and this process goes on on
00:10:19
and on and on until the battery
00:10:20
basically dies out if it's a battery and
00:10:22
it can't Supply any more electrons or if
00:10:24
it's a wall it just keeps going and
00:10:26
going forever and you get charged for it
00:10:28
right it comes from the power plant
00:10:29
but the electrons are really and truly
00:10:31
what's
00:10:32
moving now let me blow your mind a
00:10:35
little bit here uh in a basic basic
00:10:37
circuits course like a hobby book like
00:10:39
you know go to Barnes & Noble or
00:10:41
somewhere and just get a book on
00:10:43
electricity they'll talk about the
00:10:45
electrons moving but when you get into
00:10:47
engineering and you really start trying
00:10:48
to analyze how a circuit's going to
00:10:50
really behave it's a little bit
00:10:52
cumbersome to talk about the electrons
00:10:54
moving even though that's really what's
00:10:55
happening in real life the reason that
00:10:57
it's a little bit cumbersome is because
00:10:59
really one reason electrons have a
00:11:02
negative charge they have a negative
00:11:03
charge and what we're going to do later
00:11:05
on is we're going to have a circuit and
00:11:07
we're going to write equations simple
00:11:09
algebra equations so don't get too
00:11:10
worried about them but they're going to
00:11:12
be equations and they're going to
00:11:13
describe how the current is moving if we
00:11:16
do that for a bunch of negative
00:11:19
electrons then we're going to have
00:11:20
negative signs running around all of our
00:11:22
equations for our electric circuits and
00:11:25
that would totally work totally work
00:11:28
however it's a little to have negative
00:11:30
signs running around all of our
00:11:31
equations so in real life from from this
00:11:34
moment on I'm just teaching you this to
00:11:36
give you background but From This Moment
00:11:37
On We're not really going to talk about
00:11:39
electron current flow or electric
00:11:42
current flow we're not really going to
00:11:43
be talking about the direction that the
00:11:45
electrons are moving let me show you
00:11:47
what we are going to talk about in this
00:11:49
very same wire you may have to stare at
00:11:52
this a little while to realize this but
00:11:54
I think you should be able to convince
00:11:55
yourself that since this charge is
00:11:58
jumping this dire direction for a
00:12:00
temporary moment like it's we're talking
00:12:02
about a chain reaction right this one
00:12:04
moves here then this one moves here and
00:12:05
this one moves here but at the very
00:12:07
moment that this um negative charge
00:12:10
jumps away for a split second this atom
00:12:13
has lost an electron right so it's an
00:12:16
electrically neutral atom it's zero
00:12:18
charge altogether because the electrons
00:12:21
and the protons cancel out they're the
00:12:22
same number but as soon as I lose one of
00:12:24
these electrons I have sort of a
00:12:26
positive charge left
00:12:27
over right same thing happens here when
00:12:30
I lose this guy for a split moment I
00:12:32
have a positive charge here so as these
00:12:34
negative charges jump this direction
00:12:37
mathematically it's the same thing as
00:12:39
pretending that I have positive charges
00:12:42
jumping this direction the opposite
00:12:44
direction because this guy's lost an
00:12:47
electron and then the guy before it
00:12:49
loses one and before it so as these guys
00:12:51
move this way it's the same as saying
00:12:53
mathematically a positive charge goes
00:12:55
the other direction um I hope that makes
00:12:58
sense to you qual aely um based on my
00:13:01
drawing here but if it doesn't all you
00:13:03
really have to remember is
00:13:06
that the real current that we talk about
00:13:09
in engineering is called the whole
00:13:13
current and it goes in an opposite
00:13:16
direction from the electric current
00:13:17
which is the real life thing that's
00:13:19
happening and it's a mathematical
00:13:20
convenience because since now instead of
00:13:22
talking about negative electrons moving
00:13:25
this way we talk about positive charges
00:13:27
moving this way now we have positive
00:13:29
charges in all of our equations and all
00:13:31
of our equations are have rid themselves
00:13:33
of all these negative signs or at least
00:13:35
a lot of the negative signs right and it
00:13:37
makes it a lot easier to deal with so
00:13:39
it's really saving you time if you think
00:13:41
about it that way it's saving you
00:13:42
thought process
00:13:45
so uh the real electrons are going this
00:13:47
way but we pretend that we have an equal
00:13:49
and opposite number of positive charges
00:13:51
going the same direction we call it a
00:13:52
whole current the reason it's called a
00:13:54
whole current is because for a split
00:13:55
second when this electron leaves it's
00:13:57
left like a hole behind on this atom
00:14:00
which is making it that guy positive so
00:14:04
the whole current actually comes out of
00:14:06
the positive terminal like this right
00:14:09
and we say we denote that current I in
00:14:13
electrical engineering or in engineering
00:14:15
and it's the whole
00:14:20
current this is such an important
00:14:22
concept that you really should not go on
00:14:24
until you truly internalize and make
00:14:25
sure basically all you need to remember
00:14:28
in the big picture is that anytime you
00:14:30
have a circuit the source is going to
00:14:32
always have a positive and a negative
00:14:34
terminal always just like any battery if
00:14:35
you pull a battery out of the box you'll
00:14:37
see one side's labeled positive one
00:14:38
side's label negative in real life if
00:14:40
you hook the battery up to something
00:14:42
electrons are the really the objects
00:14:44
that come around from the negative
00:14:45
terminal back to the positive but in in
00:14:48
electrical or in any kind of an
00:14:49
engineering course when you're taking a
00:14:51
circuits class you never ever ever talk
00:14:53
about the electron flow in this this
00:14:56
direction this way you always instead
00:14:58
talk about the positive current flow
00:14:59
it's the same value going in opposite
00:15:03
directions and it makes the equations
00:15:05
much much simpler and in fact all the
00:15:07
power calculations the the function of
00:15:10
the circuit the energy all everything is
00:15:13
completely and totally described by
00:15:15
talking about this sort of like this
00:15:16
pretend current that's going in the
00:15:18
opposite way so just get used to seeing
00:15:20
that you're always going to pretend that
00:15:21
your current's coming out of the
00:15:22
positive terminal even though in reality
00:15:24
the electrons are bleeding out the other
00:15:25
side now the units of uh electric
00:15:30
current uh I talked I told you briefly
00:15:32
current is denoted I right I it probably
00:15:36
is some history to it you could go look
00:15:38
it up you would think current would be
00:15:39
called C but it's not it's called I um
00:15:42
so anytime you see I labeled in a
00:15:44
circuit that is the electric or that's
00:15:47
the current flowing through that branch
00:15:48
of the circuit or something of that
00:15:50
nature now what are the units of current
00:15:53
a lot of you have already heard this uh
00:15:55
units let's go and change colors a
00:15:57
little bit the units for
00:16:02
current is the
00:16:06
Ampere which is also called an amp right
00:16:11
um or you can call it simply
00:16:15
a right the higher the number of of amps
00:16:19
the um you know the higher the the
00:16:22
current going through the circuit
00:16:23
basically an ampere is telling you how
00:16:25
many charges are moving through your
00:16:27
circuit per second and there's a a
00:16:29
definition in physics that you could go
00:16:30
look up for that and that's fine it's
00:16:32
not terribly important because you know
00:16:34
really we're always talking in circuits
00:16:36
you know in in a physics class you'd be
00:16:38
talking about an individual charge
00:16:39
moving there's so many coolum on a
00:16:41
charge moving right but in a circuit you
00:16:43
got billions of charges in this in the
00:16:45
guy so you don't talk about coolum and
00:16:47
and how many kums of charge are crossing
00:16:49
through a boundary you just look at the
00:16:51
aggregate which is how many ampers which
00:16:53
is a coolum per second how many kums per
00:16:55
second really are going through that guy
00:16:58
so an amp here represents how many kums
00:17:00
of charge are passing if you were to
00:17:02
slice this wire and watch how many go
00:17:04
through there that would be how many
00:17:05
coolum of charge go through there per
00:17:07
second but really you don't have to deal
00:17:09
with that too much in in a circuits
00:17:10
class we're always going to be talking
00:17:11
about amps or ampers so bringing it back
00:17:14
to the everyday language that everybody
00:17:16
already knows you you've heard of amps
00:17:18
right everybody's heard of amps um that
00:17:20
is the current flow the higher the
00:17:22
number of amps in that circuit is the
00:17:24
the more it can potentially kill you
00:17:26
right it doesn't take much current to
00:17:27
kill a person actually uh believe it or
00:17:29
not so you might have a car stereo that
00:17:32
has you know a 10 amp amplifier right it
00:17:34
means 10 amps of current are flowing
00:17:36
around that amplifier because to push
00:17:38
the sound into those speakers and get
00:17:39
them to move really loud um you need a
00:17:41
lot of physical electricity to do that
00:17:44
right to actually get it to move like
00:17:45
that but in a computer inside of a
00:17:47
microchip you might have a teeny tiny
00:17:50
amount of current going around because
00:17:51
those are very delicate circuits you
00:17:52
might have a milliamp or a micro amp
00:17:55
inside of those guys but the base unit
00:17:57
of current is always going to be the the
00:17:59
Ampere which is which is what we have
00:18:00
right here all right so to sum it up uh
00:18:05
which is really so important I keep
00:18:07
talking about it current uh in general
00:18:09
in real life is the flow of electrons
00:18:11
however in all circuits from henceforth
00:18:13
that we're going to talk about we're not
00:18:14
even going to talk about this we're just
00:18:15
going to say the current comes out of
00:18:17
the positive terminal and the unit is
00:18:19
ampere that's really the bottom line all
00:18:22
right now the next thing we have is the
00:18:24
concept of
00:18:26
voltage which many many many people get
00:18:29
confused with current because it's kind
00:18:31
of used interchangeably voltage is the
00:18:34
push I'm going I put in quotes the
00:18:38
push that
00:18:44
causes the current to
00:18:52
flow so in other words it's the source
00:18:55
right it's the source so when you look
00:18:57
at a n Vol battery that battery comes in
00:19:00
a physical size it has 9 volts 9 volts
00:19:03
mean is a relative indicator to tell you
00:19:06
how much oomph for lack of a better word
00:19:08
um that battery can push in a circuit so
00:19:11
the um current and the voltage are very
00:19:14
very closely related you cannot have any
00:19:16
current flowing without something
00:19:18
pushing it and so you have to have some
00:19:20
Source there to push it which is usually
00:19:22
a battery or a wall socket or something
00:19:24
like that and that's always measured in
00:19:26
volts so when you when you see on TV you
00:19:29
know oh boy you could be killed by
00:19:31
10,000 volts well 10,000 volts is not
00:19:34
really how much current is flowing
00:19:35
through you that's just how much push
00:19:37
there is so to kind of bring it down to
00:19:40
to layman's terms think about a straw
00:19:43
Pretend This Were a soda straw that you
00:19:44
get at a restaurant right and let's say
00:19:47
it's a pretty narrow straw like a almost
00:19:50
like a straw that you use to stir your
00:19:51
coffee okay now if I blow on it like
00:19:54
this then I'm going to be pushing air
00:19:56
through that straw the current
00:19:59
is the air that's actually moving
00:20:01
through the straw right that's what the
00:20:03
current is that's what's actually doing
00:20:04
the movement and doing the work all
00:20:06
right now I'm actually blowing on it so
00:20:09
I'm pushing I'm actually increasing the
00:20:10
pressure at the at the end of that thing
00:20:13
that's causing the current to move
00:20:15
that's the voltage the push that I give
00:20:17
it the pressure that I give it is what's
00:20:19
actually causing the current to move or
00:20:22
the in this case the air to move through
00:20:24
the straw if I don't blow and I don't
00:20:26
give any pressure then there's no
00:20:28
current there's no flow of air through
00:20:29
the straw same thing in a circuit if the
00:20:32
voltage is zero you know coming out of
00:20:34
the source here then there's no current
00:20:36
so the two are very closely related it's
00:20:38
just that the voltage is the push and
00:20:40
the current is actually what's moving
00:20:42
that's really the the main thing to take
00:20:44
away from this guy um so it usually
00:20:47
comes from a where it always comes from
00:20:48
a battery or some kind of other source
00:20:50
that you might get uh that's generated
00:20:52
out of the wall now for the units of
00:20:55
voltage the units
00:20:59
is the
00:21:01
Volt or simply call it
00:21:04
V uh so that's just that's the uh the
00:21:08
same thing as the current the more the
00:21:10
more volts you have the higher the
00:21:11
voltage you have the more potential to
00:21:14
move current through a circuit you have
00:21:16
so that's why 10,000 volts is so much
00:21:18
more dangerous than one volt um it's not
00:21:20
because it's measuring how much current
00:21:21
is going through your body it's just
00:21:23
that if I grab on to a 10,000 volt fence
00:21:26
it has the potential to push a ton of
00:21:28
current through my body right whereas a
00:21:30
1vt source since it's so much less of a
00:21:32
push so to speak um it's not really
00:21:34
going to do very much to me uh right so
00:21:36
that's really the main difference so
00:21:38
current and voltage tied at the hip but
00:21:39
two different things U the biggest faux
00:21:42
paw you can kind of get into is saying
00:21:43
boy that was a really impressive circuit
00:21:45
that had 39,000 volts of electricity
00:21:47
flowing through your body that sentence
00:21:49
makes no sense voltage does not flow
00:21:52
through your body only current does
00:21:54
voltage is what actually pushes the
00:21:55
current through your body that's really
00:21:57
the main distinction
00:21:59
now tied to all of this is it the uh
00:22:02
very very important concept of
00:22:07
resistance all right
00:22:09
resistance resistance is very very
00:22:11
simple to understand it
00:22:15
opposes the current
00:22:20
flow in a
00:22:25
circuit this might be a little bit
00:22:27
confusing at first but think about our
00:22:29
soda straw all right for a second
00:22:31
pretend for a second we didn't have
00:22:32
actually a soda straw let's say we had
00:22:34
something really big like a paper towel
00:22:35
tube like you have you get the paper
00:22:37
towels at the grocery store and there's
00:22:38
a giant cardboard tube in the middle I
00:22:41
stick that to my mouth and I blow it's
00:22:43
pretty easy to blow through a paper
00:22:45
towel tube because it's so big right so
00:22:47
I can blow all day as long as my lungs
00:22:49
can do it I can blow lots and lots and
00:22:51
lots of air through there right with
00:22:53
really not much effort I don't really
00:22:54
have to push that hard to to actually
00:22:57
make that air move because it's just so
00:22:59
big so we say that the resistance for
00:23:02
lack of a better word of this guy to air
00:23:04
flow is not very big it's got a low
00:23:06
resistance right now let's compare and
00:23:08
contrast that let's go back to our
00:23:10
coffee stirring straw very very tiny
00:23:14
diameter so for that one to get any kind
00:23:17
of air movement through it I've got to
00:23:18
blow pretty hard and I can feel it in my
00:23:20
lips I'm I'm really blowing because we
00:23:23
say that the resistance of that smaller
00:23:25
straw is much higher the resistance to
00:23:28
air flow higher because it's physically
00:23:29
constrained you cannot force that much
00:23:31
air through that straw very easily I
00:23:34
mean you can do it but you have to blow
00:23:36
really hard so we say the resistance is
00:23:38
much higher for that guy and actually
00:23:40
that analogy directly translates to uh
00:23:43
to electric circuits as well if I
00:23:45
literally have a wire a uh you know a
00:23:48
copper wire as big around as my as I'm
00:23:50
demonstrating here this big around it
00:23:52
has a very very very low resistance the
00:23:55
cross-section mean is so big that tons
00:23:58
of electrons can move through there tons
00:24:00
of electricity can move through there
00:24:01
without really much resistance because
00:24:03
it's so big but if I go get a wire
00:24:06
thinner than my hair or maybe I go get a
00:24:09
tiny wire etched onto a computer circuit
00:24:12
chip which are so small that you have to
00:24:14
have a microscope to see them then the
00:24:16
cross-section of a teeny tiny wire like
00:24:18
that is going to be so small it's going
00:24:20
to actually resist the current the
00:24:22
electricity is going to get to move
00:24:23
through there but it's going to cause
00:24:24
friction there's just not as many atoms
00:24:27
there for it to move so the resistance
00:24:29
is going to be higher so for the smaller
00:24:31
the object the resistance is always
00:24:32
going to be higher the bigger the object
00:24:34
the resistance is going to be smaller so
00:24:37
think of it that way it's resisting and
00:24:39
it's opposing current flow not because
00:24:41
something intelligent is in charge of it
00:24:43
it's just because of the size of it
00:24:44
usually or the way it's constructed so
00:24:47
current voltage resistance they're all
00:24:49
so intertwined because of of the analogy
00:24:52
with the soda straw really the
00:24:54
resistance when the resistance is
00:24:55
smaller like the big paper towel tube
00:24:58
right then I can move a lot of air a lot
00:25:00
of current without much effort with a a
00:25:03
lower voltage right and and when I go to
00:25:05
a smaller straw I can still move current
00:25:08
but it's going to take more effort More
00:25:09
Voltage to get the same amount of
00:25:11
current flow or to get the same amount
00:25:13
of current flow through that resistance
00:25:14
so current voltage resistance are really
00:25:16
all tight at the hip really as as far as
00:25:18
being interrelated now the units of
00:25:22
resistance the
00:25:24
units is called the
00:25:26
ohm ohm but you never actually write ohm
00:25:29
in a circuit you always use this Omega
00:25:32
this Capital Omega and so when you have
00:25:35
a a five Ohm resistor has more
00:25:38
resistance than a 1 ohm resistor a
00:25:41
resistor we'll talk about in the next
00:25:42
section but they actually have a circuit
00:25:44
component called a resistor whose job is
00:25:46
to resist current flow seems weird why
00:25:49
you would ever need that we'll get to
00:25:50
the reasons why you would need that
00:25:51
later but that little guy is going to
00:25:54
try to stop the current flow to a up to
00:25:56
a certain point and so the higher the
00:25:57
value the more it's trying to resist the
00:26:00
current flow right just like the the
00:26:01
little examples that we were given
00:26:03
before so very very important topics
00:26:06
current is the flow of electricity
00:26:07
voltage is how much push you are pushing
00:26:09
to make this current flow and you're
00:26:11
always flowing through something that
00:26:13
something is always going to have a
00:26:14
resistance different size wire different
00:26:17
resistors uh different circuit
00:26:18
components are going to manifest
00:26:20
themselves as different uh values of of
00:26:22
however many ohms now for all of these
00:26:25
guys I've kind of hinted here but I'll
00:26:27
just spell it out
00:26:29
we can use the
00:26:32
metric
00:26:34
prefixes for all of these guys right
00:26:38
because these are standard units we can
00:26:39
use the metric prefixes so for instance
00:26:42
if you're talking about amps which is
00:26:44
current flow it may not make sense to
00:26:46
talk about amps you might need to talk
00:26:48
about
00:26:49
milliamps right milliamps just like a
00:26:51
millimeter that's one 1,000th of an amp
00:26:54
right or you might talk about micro amps
00:26:57
right 10 Theus 6 amps Etc something like
00:27:01
this right so the base unit is always
00:27:03
amps it's just you have a metric
00:27:05
modifier on the front you might have
00:27:07
resistance how many ohms you're talking
00:27:10
about in the circuit but it might make
00:27:11
more sense to talk about milliohms if
00:27:13
it's a very small resistance or even if
00:27:16
it's tiny tiny micro ohms right that's
00:27:19
10us 6 ohms right or if it's a large
00:27:23
value maybe you have kiloohms or maybe
00:27:25
you even have mega ohms which is
00:27:27
millions of ohms right or here kilohms
00:27:30
is thousands of ohms so the the metric
00:27:32
system applies here there's nothing
00:27:33
special and for voltage maybe you have
00:27:35
Mill volts you know maybe you have
00:27:38
kilovolts you know maybe you have mega
00:27:40
volts maybe a nuclear power plant is
00:27:42
operating at so many megga volts or
00:27:43
something like that very very important
00:27:45
Concepts I can't stress them enough so
00:27:48
uh we've talked about current we've
00:27:51
talked about voltage we've talked about
00:27:53
resistance in detail uh because it's so
00:27:56
important for you to understand what
00:27:57
that stuff is it'll make my job easier
00:27:59
whenever we start talking about circuits
00:28:01
that you're not scratching your head
00:28:02
what's the voltage again I can't
00:28:03
remember I mean I really need you to
00:28:05
understand that before we get to
00:28:05
anything else now let's talk about some
00:28:08
uh General things that you probably
00:28:10
heard growing up uh General uh
00:28:12
definitions so to speak that you
00:28:14
probably heard first one is DC and AC uh
00:28:17
DC versus AC let's talk about that for
00:28:19
just a second uh because it's you know
00:28:22
it's something that we need to make sure
00:28:23
you understand DC this stands for direct
00:28:26
current
00:28:31
right and uh basically what it means is
00:28:37
constant current
00:28:43
flow basically all of the batteries
00:28:46
you've ever used in your life the aaa's
00:28:48
the doublea's the 9 volts watch
00:28:51
batteries I mean anything that anything
00:28:53
built into a little device that we
00:28:55
called battery always generates a direct
00:28:56
current it means that when you hook it
00:28:58
up to the Circuit it's giving you a
00:29:00
constant voltage at the source location
00:29:03
right that's pushing current around and
00:29:05
because it's a constant voltage it's
00:29:07
providing the current that comes out is
00:29:08
constant never changes now in reality
00:29:11
the battery is going to die down and
00:29:12
it's going to get weaker and weaker so
00:29:14
the current does eventually bleed off
00:29:15
but I mean if you take a snapshot and
00:29:17
look at it the current is a constant
00:29:19
it's called direct current all right now
00:29:21
let me contrast that to AC which I know
00:29:25
you've heard of and that's called
00:29:27
alternating
00:29:33
current alternating current uh and this
00:29:37
means um well exactly what it sounds
00:29:39
like it's it's a wall
00:29:45
socket and it means the
00:29:48
current for lack of a better word
00:29:51
moves
00:29:54
back and forth
00:29:58
and this is really uh actually much
00:30:00
easier to understand what the what the
00:30:01
purpose of uh with the a drawing here so
00:30:03
let's draw a quick little circuit like
00:30:06
this now normally we've been putting
00:30:08
plus minus but here I'm just going to
00:30:10
kind of put a little wave in here to
00:30:12
kind of indicate to you that this is a
00:30:14
alternating current and we'll get into
00:30:16
all these symbols later you know in
00:30:19
detail I'm just trying to get the idea
00:30:21
uh out to you what this means and this
00:30:23
is a a great a great model for what's
00:30:24
happening in your wall socket when you
00:30:26
plug something in you know into the wall
00:30:28
what happens is at first the current
00:30:30
comes out this direction and flows this
00:30:32
way and then it starts to slow down and
00:30:34
then it goes back the other way like
00:30:36
this and then it goes back the other way
00:30:39
and it goes back the other way it
00:30:40
literally alternates the direction of
00:30:42
the current if you could actually see
00:30:44
the electricity coming out of your wall
00:30:46
like if you could if you I'm looking at
00:30:47
a plug right now over there in the wall
00:30:49
if you can visualize a plug you know
00:30:51
everybody kind of thinks and realizes
00:30:53
there's electricity coming out but if
00:30:55
you could see the electricity you would
00:30:56
see the electricity racing out and then
00:30:59
slowing down and then going right back
00:31:01
into the wall and coming out the other
00:31:02
way and then racing back into the wall
00:31:04
and coming back the other way and it
00:31:05
alternates back and forth back and forth
00:31:07
back and forth back and forth how many
00:31:08
times does it do that well in the United
00:31:11
States it's 60 times a second 60 UH 60
00:31:14
hertz that's a unit of frequency that's
00:31:16
how fast it's coming back and forth 60
00:31:18
times every second that electricity is
00:31:20
switching directions right now you might
00:31:23
say I should say the the number one
00:31:25
question you get when you explain
00:31:26
alternating current direct current is
00:31:28
why do we have a difference why do we
00:31:29
have a difference well the reason mainly
00:31:32
is um is a lot of history actually but
00:31:35
truthfully whenever you generate
00:31:36
electricity at a power plant to feed
00:31:39
houses it's much easier to generate it
00:31:41
as alternating current and uh it's much
00:31:44
easier to transmit it out to the homes
00:31:46
as alternating current and that goes
00:31:48
into a lot of theory that I can't get
00:31:49
into right now but just trust me on that
00:31:51
it's a little bit easier um you know
00:31:53
really all of our power plants whether
00:31:55
they're gas or nuclear or or coal or
00:31:59
anything all they do is generate a lot
00:32:01
of heat and that heat heats up steam
00:32:04
usually and that steam turns a generator
00:32:06
so all of our power plants no matter how
00:32:08
fancy even the wind farms out there
00:32:10
they're just turning a generator so
00:32:13
since they're moving like this the
00:32:15
current that's generated actually
00:32:16
alternates back and forth and it comes
00:32:18
directly because every time we generate
00:32:20
electricity the only way we really know
00:32:21
how except for solar panels we're doing
00:32:24
it by rotating a wire inside of a
00:32:26
magnetic field which is what's inside of
00:32:28
a generator because of that motion of
00:32:30
rotation is is a direct result of how we
00:32:32
get alternating current and that's the
00:32:33
really the reason why the power plants
00:32:35
do that when we build a battery it's a
00:32:37
chemical reaction you it's either on or
00:32:39
it's off there's no motion inside of a
00:32:41
battery right so it's just going to give
00:32:43
you that constant deal the constant
00:32:45
current the constant voltage so that's
00:32:47
the difference between DC and AC in this
00:32:49
class we're going to focus on DC first
00:32:51
we're going to learn all the techniques
00:32:52
of analyzing DC circuits um because
00:32:56
really when you get to AC it's what once
00:32:58
I show you the method it's really not
00:33:00
that different so we're we're going to
00:33:02
do DC first get really good at it and
00:33:04
then we're going to introduce the
00:33:04
Alterna and current uh mechanism just a
00:33:08
couple of other definitions I want to
00:33:09
get to real quick before we call a day
00:33:11
everybody's heard of this what is an
00:33:13
open
00:33:16
circuit what do you think an open
00:33:18
circuit is uh well if you have a circuit
00:33:21
right if you have a circuit um it's
00:33:23
supposed to come all the way back to
00:33:25
where it started if you have an open
00:33:27
circuit it means somewhere along that
00:33:29
path it's broken basically so an open
00:33:32
circuit would be if I had some kind of
00:33:34
source here like here and then I had a
00:33:37
break in it make this break a little
00:33:39
bigger uh then there's no more current
00:33:41
flow you cannot have current flow in an
00:33:44
open circuit by definition so this open
00:33:46
here this is what your wall switch does
00:33:48
when you flip the wall switch it just
00:33:50
breaks open the circuit so no
00:33:52
electricity can flow anymore that's what
00:33:53
we call an open circuit now let's also
00:33:56
take a moment to talk about a a short
00:33:59
circuit
00:34:04
short lots of people have heard of short
00:34:06
circuit most people know that short
00:34:08
circuit is not really good thing but a
00:34:10
lot of people don't know what a short
00:34:11
circuit really means um when you think
00:34:13
about it if you have a circuit you've
00:34:15
got a source and you're supplying energy
00:34:17
or electricity to some load over here we
00:34:19
call it could be a light bulb could be a
00:34:21
fan could be a anything uh right so in
00:34:25
general for every circuit
00:34:27
that's operating we're going to have
00:34:29
something over here that we're supplying
00:34:31
power to right this could be anything at
00:34:32
all I'm going to put a giant box here
00:34:34
this could be you know a fan for
00:34:36
instance right and this electricity is
00:34:39
coming out this current is coming out
00:34:41
into the fan causing the fan to turn and
00:34:43
I'm leaving a lot of details out but
00:34:44
that's basically it now inside of your
00:34:47
circuit let's say I somehow a piece of
00:34:50
wire kind of accidentally connects from
00:34:54
here to here maybe you're working in a
00:34:56
building let's say you're building the
00:34:58
building you're pulling the wire through
00:34:59
the building and somehow a stray piece
00:35:01
of wire gets connected to two terminals
00:35:04
like this or maybe inside of your lamp
00:35:07
you uh develop a short circuit because
00:35:08
the two wires that that are supposed to
00:35:10
go to the light bulb maybe they start to
00:35:12
touch on accident what happens is the
00:35:15
electricity is coming out here and when
00:35:17
it gets to this Junction right here it
00:35:19
has a choice to go this way through the
00:35:21
fan or this way now let me ask you a
00:35:23
question what do you think is going to
00:35:24
be the lower resistance do you think
00:35:26
it's going to be lower resistance for
00:35:27
the electricity to go through this giant
00:35:29
fan and spin something around or do you
00:35:31
think it's going to be a lower
00:35:32
resistance for this electricity to try
00:35:34
to go through this little piece of wire
00:35:35
that you put there it's going to be much
00:35:37
much easier for the electricity to Go
00:35:39
Through the Wire and so electricity is
00:35:42
always going to do that it always tries
00:35:43
to go through the path of least
00:35:45
resistance just like you do when you're
00:35:47
in traffic right you try to go the path
00:35:48
of least resistance so because of that
00:35:50
the electricity never even gets to the
00:35:52
fan so that's called a short circuit
00:35:54
it's called short because it kind of
00:35:56
truncates the circuit or it shortens off
00:35:58
the circuit uh and it's very bad uh for
00:36:01
lots of reason because whenever you
00:36:03
start to get current going through a
00:36:05
wire like this with no resistance or
00:36:07
very low resistance you can actually
00:36:10
generate a lot of heat and you can
00:36:11
actually cause a fire actually and
00:36:13
that's why you have those circuit
00:36:14
breakers outside of your home those are
00:36:16
there to detect if any short circuits
00:36:19
happen to detect the extra current The
00:36:21
increased current that comes from it and
00:36:23
to shut them off if you get any kind of
00:36:25
a short circuit in your washer or your
00:36:27
dryer maybe some wies start to touch the
00:36:29
current is going to start to go up
00:36:31
really really fast through this tiny
00:36:32
little leg and your circuit breaker is
00:36:35
in is in the circuit with that it
00:36:36
detects that and then it shuts the
00:36:38
circuit down so that's basically how
00:36:40
that how that works that is uh about how
00:36:45
all I want to talk about in this lesson
00:36:46
we've covered a lot of things we haven't
00:36:49
done any math that's okay because you
00:36:51
know sometimes in the beginning you
00:36:53
really need to take some time to
00:36:54
understand the fundamentals so we
00:36:56
learned about the Circ you always have
00:36:58
to have a complete circuit to have any
00:36:59
electricity flowing we learned about
00:37:02
current it's the flow of electrons in
00:37:04
real life but in in a circuit analysis
00:37:06
we don't talk about that we talk about
00:37:07
the positive current going in the other
00:37:09
direction has a symbol of I all right uh
00:37:12
in in terms of our equations right the
00:37:15
unit is amp or or a of course we can
00:37:17
talk about milliamps microamps uh
00:37:19
kiloamps things like that as well uh and
00:37:22
then we talked about the voltage which
00:37:23
is related the voltage is the push that
00:37:25
pushes the electric current around in
00:37:27
the circuit the higher the voltage then
00:37:29
the more push you have the more current
00:37:30
you're going to end up getting because
00:37:31
you're pushing you're pushing through
00:37:33
with more Force for lack of a better
00:37:34
word right the units is a voltage that
00:37:37
we talk about or of course you have Mill
00:37:39
volts microvolts
00:37:41
Etc uh and then we talked about
00:37:43
resistance which is integral to all that
00:37:44
that is sort of a property of the
00:37:46
circuit or the property of the wire the
00:37:48
property of the components and it
00:37:49
literally tries to oppose the electric
00:37:52
current the unit is the ohm which is the
00:37:55
capital Omega here of course you could
00:37:56
have million microohms kiloohms with
00:37:59
that guy just like you have for the
00:38:00
others and then we talked about some
00:38:02
other random definitions that people
00:38:04
have heard over the years of growing up
00:38:05
direct current DC alternating current AC
00:38:08
this guy is usually coming from a
00:38:10
battery some constant current Source
00:38:11
usually a chemical reaction is giving
00:38:13
you a constant voltage constant current
00:38:15
coming out all the time alternating
00:38:18
current comes out of your wall the
00:38:19
reason it's alternating is because it's
00:38:21
easier to generate because you have
00:38:22
rotating generators and you have easier
00:38:25
transmission to the homes there's a lot
00:38:26
of theory in that but that's basically
00:38:28
the the deal and both are you know both
00:38:31
are electricity the fact that it
00:38:32
alternates doesn't really mean much I
00:38:35
mean you're your light bulb you don't
00:38:36
see it flickering but the electricity is
00:38:38
actually going through your light bulb
00:38:39
back and forth 60 times every second you
00:38:41
don't see it because it's so fast so I
00:38:43
don't get too wrapped up or hung up on
00:38:45
the difference here they're both
00:38:46
electricity they both deliver energy and
00:38:48
then we talked about open circuit you
00:38:50
have a circuit where you literally take
00:38:52
a piece of scissors and cut it open no
00:38:54
electricity can flow anymore and a short
00:38:56
circuit is when you have an operat ating
00:38:57
circuit that you that you um
00:38:59
accidentally Bridge or connect two
00:39:01
pieces across together and it basically
00:39:04
causes the electricity to not even go
00:39:06
into the load at all so the load stops
00:39:08
working you get tons of current built up
00:39:11
here and it can actually lead to smoke
00:39:13
and fire if you let it go and that's why
00:39:14
we have those circuit breakers in our
00:39:16
homes so that's what we want to cover in
00:39:18
this section the title was voltage
00:39:20
current and resistance it's so important
00:39:22
to understand so make sure and watch
00:39:23
this until you feel pretty comfortable
00:39:25
with it the next few sections I want do
00:39:27
some more background stuff we'll talk
00:39:29
about taking an overview of of the
00:39:31
circuit components out there and then
00:39:33
we'll do another lesson on on what we
00:39:36
call ohms law which in mathematical
00:39:38
terms relates uh resistance current and
00:39:42
voltage together and I promise you Ohm's
00:39:44
law is so simple that you know you'll
00:39:46
you it'll just Boggle your mind it's
00:39:48
very very simple to understand and then
00:39:50
once we get those Foundation things
00:39:51
going going on then we can really start
00:39:54
diving into some real real circuits and
00:39:56
looking at the current is going to move
00:39:58
through the branches how they're going
00:40:00
to sum together what's going to be the
00:40:01
value of the voltage here the voltage
00:40:03
there and then we can get into some more
00:40:05
complicated circuit components like
00:40:06
capacitors and inductors and much later
00:40:09
even what we call transistors and dodes
00:40:11
and things like that and you'll be
00:40:13
introduced slowly but surely over time
00:40:15
to this beautiful thing I think that we
00:40:17
have in the 21st century called you know
00:40:20
electric circuit so the nice thing about
00:40:22
it is you can learn this stuff you can
00:40:24
you know academically understand it it's
00:40:27
good for your career and things if
00:40:28
that's what you plan to go into but also
00:40:31
you can take a trip to the store buy a
00:40:32
few components once you know what you're
00:40:34
doing and you can build a radio if you
00:40:36
want to you can build a blinking light
00:40:38
if you want to you can build an alpha
00:40:40
numeric display if you want to so it's
00:40:42
one of the few things that you can
00:40:43
really learn that once you understand it
00:40:45
you can really go out there and build it
00:40:47
if you learn about nuclear power plants
00:40:49
they're amazing but you're not going to
00:40:50
be able to go build a nuclear power
00:40:51
plant if you learn about Einstein's
00:40:53
theory of relativity it's amazing I love
00:40:55
that stuff but I'm not going to be able
00:40:57
to really test it myself but with
00:40:58
circuits once you understand it and
00:41:00
learn it you can actually play around
00:41:02
with it and that's what I find so
00:41:03
fascinating about it so I hope I've
00:41:05
kindled your interest a little bit stay
00:41:07
with me we're going to go through the
00:41:08
sections and and dive into all of these
00:41:10
circuit analysis techniques I'll try to
00:41:12
make them as simple as possible but you
00:41:14
do need to practice your problems
00:41:16
practice the problems that we present
00:41:17
here and also the extra problems that
00:41:20
are in your textbook