History of Electricity Part One

Did you know that engineers were harnessing electricity long before they even knew what it was? We take a look at the history and tech behind electricity.

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Episode Transcript

Speaker 1 (00:04):
Get technology with tech Stuff from how stuff works dot com.
Hey there, and welcome to tech Stuff. I'm your host,
Jonathan Strickland. I'm a senior writer for how stuff works
dot com, and today we're gonna take a look at
the history of electricity, from the earliest experiments all the

(00:27):
way up to the formation of today's power grid and
how it all works. Well, at least in this part,
we're gonna explore the first section of that history. But
as it turns out, the history of our experimentation and
knowledge of electricity is exhaustive and I would really need
to do more than one episode. So this is part
one of what is likely to be a two part

(00:49):
episode about the history of electricity. I'll try to limit
the number of electricity based puns I will drop in
this episode, but don't be shocked if you hear a
few of them. So first, let's define what electricity is,
or rather, instead of letting me define it, let's use
Miriam Webster, because that's kind of their job. Electricity is

(01:12):
a fundamental form of energy, observable in positive and negative forms,
that occurs naturally as in lightening, or is produced as
in a generator, and that is expressed in terms of
the movement and interaction of electrons. That's actually kind of
a little simplistic. It's talking about the move of electrons.
It's really more about the move of electric charge and

(01:33):
not of electrons. Specifically, if you had some other carrier
that was carrying electric charge, it would be more about
the movement of that carrier. As it turns out, electrons
are the naturally occurring negatively charged particles sub atomic particles
that are concerned, especially with electronics. So it's understandable, but

(01:55):
I just want to point that out that it's really
more about electric charge and less about the actual sub
stomic particles. Uh, don't worry, even though we'll be talking
a lot about electrons. I promise this show won't be
too negative. And I'm seriously done with puns for just
a bit now. To further define electricity, it helps if
we get some basic ideas established. Now, keep in mind

(02:18):
these aspects of electricity were not understood for centuries. So
when I go into the history of electricity, remember that
for the vast majority of our experience working with and
trying to understand electricity, we did not have any knowledge
of the underpinning foundational physics. Right. We were making observations

(02:41):
and we were even building things that could take advantage
of this stuff, but we didn't actually understand what it
was doing or how it was working, which I always
find really fascinating, this idea that we can harness something
without fully understanding what it is and how it works.
But it's good for us, as in myself and you
guys the audience, to understand some of these basics before

(03:04):
we get too far into the discussion. Otherwise I have
to keep interrupting the history lesson for science lessons, and
then it gets kind of a little complicated. Some of
that's gonna happen anyway, but I want to get the
foundation out of the way. So the most important thing
to remember here is that we're talking electric charge, and

(03:27):
we want to make sure we can make sense of this.
It's time to get current on our terms. So I
guess that really wasn't the last pun I'll be talking about.
So electric charge comes in two flavors, positive and negative,
positive charge and negative charge. You're probably very familiar with
us on the sub atomic particle level. Pot you know,

(03:47):
we have we have our our protons those are positively charged.
We have our electrons, those are negatively charged. Now, opposite
charges attract one another in circuits. A carrier moves negative
charges to a source of positive charge. So some sort
of subatomic particle needs to carry that negative charge throughout

(04:07):
the circuit until it can get to the source of
a positive charge. Because negative quote unquote wants to be
with positive. It doesn't really want anything, it's just that's
the natural tendency, right these for these two different charges
to attract one another. Now, in practical terms, the carrier
is an electron. So that's why we talk about electricity.

(04:29):
It's when we talk about electronics. Um it's the subatomic
particle that possesses negative charge. So if we do a
basic electrostatic experiment where we take a block of wax
and we rub that block of wax with some wool,
we will build up an electrostatic charge. So what's happening
is we are imparting a negative charge to the wax

(04:52):
and creating a positive charge to the wool. So, in
practical terms, that means the wax has a surplus of
electrons and the wool has a efficiency of electrons. Effectively,
you are rubbing some of the electrons from the wool
onto the wax. That makes the overall charge of the
surface of the wax negative. It makes the overall charge
of the surface of the wool positive. And if we

(05:13):
create a pathway that electrons can follow from the wax
to the wool, then electrons will take that pathway, pop
back over to the wool and sort of repair that
deficiency where that that deficiency of electrons will be balanced out,
where electrons will journey back over and rejoin, and they'll

(05:35):
probably be a big party, you know, or at least
a subatomic one. And that's that's the basics for electric charge.
So now we have to build on this foundation. There
are three other basic concepts that we need to understand,
and those are voltage, current, and resistance. Now these will

(05:56):
be important throughout the discussion of electricity, particularly as people
begin to get a deeper understanding of what was actually
happening with electricity. Voltage is probably the trickiest one for
people who aren't inclined toward electronics and electricity. It's all
about potential energy, specifically the potential energy represented by a
pair of different electric charges. So voltage is sort of

(06:20):
like pressure. You can imagine it as a force that
pushes electrons through a conductor, which is oversimplifying, but it's
helpful when you imagine it that way. So voltage is
the pressure in the system. The higher the voltage, the
greater the pressure, the stronger that push is. A low
voltage has very little push, while high voltage has a

(06:41):
whole lot of push, And we need voltage to make
electronics work. Otherwise nothing is going to cause a current
to flow through a circuit. You can also kind of
think of it as like potential energy in the form
of as an analogy of kinetic energy. So let's say
that you have a level surface pond which you've got
a two little corrals of marbles. They don't really have

(07:05):
any potential energy with respect to one another. They're on
the same level. But let's say you raise one of
those up, you tilt it, and you raise it up,
so the corral is still holding the marble's in. But
now the marbles have potential energy because they're at a
higher level than the lower marbles. And then let's say
you were to connect a little slide between the top
corral and the bottom corral and allow the marbles to

(07:26):
roll down the hill. Well, this would be sort of
like a copper wire connecting an area that has a
surplus of electrons to an area that has a deficiency
of electrons. It's allowing for the movement of those electrons. Now,
in the case of voltage, we're really talking about electric

(07:48):
potential here. We're not talking about kinetic energy or potential
energy that can be converted into kinetic energy. Is really
just meant as an analogy. So when we talk about
volta age, we talk about it with respect of two
points on a circuit. So a voltage difference between two
points on a single circuit and their potential difference really

(08:09):
which we may also call a voltage drop. The potential
difference between two points is measured in a unit called volts.
No big surprise there. A volt is the amount of
energy needed to force an electrical current of one ampier
more on that in a second, through a resistance of
one ohm more on that in a second, to at
a particular temperature. Now, you can have a voltage between

(08:32):
two points without having any connection between them. So you
can have a voltage between two things that do not
have an active pathway between the two. If the distance
between the two points is decreased, then that electrostatic field
that the voltage difference creates will intensify. If you increase

(08:56):
the space between those two points, the electrostatic yield will diminish.
So distance plays a factor, not just the difference in voltage.
So that covers voltage. But now let's talk about current.
So technically the current is a flow of electrical charge,
and we commonly think of it as the movement of electrons,

(09:17):
but again that's an oversimplification. You can actually have a
flow of positive charge and that would still be a current.
If you add a flow of positive charge, that's technically
a current. But when we're talking about circuits and electronics,
were really talking about electrons, not positively charged electrical charges.
So we tend to simplify it and say it's the

(09:39):
flow of electrons. Just keep in mind that that is
an oversimplification, uh, because electrons are the charge carriers of
negative charge. Now, in a way, you could think of
it as electrons are the messengers and the electric charge
they carry is the message, and that's what's really important.
But in practical terms, we can just so aplify it

(10:00):
to electrons. We measure current in ampiers, uh, and that
gives us a sense of the intensity or quantity of
a charge. So voltage is the force behind moving a charge,
and amperage tells you how much charge is actually moving.
And this can help if you start to imagine voltage

(10:20):
as being a locomotive engine and the amperage as being
a series of train cars. So a low amperage current
you might think of as just being two or three
train cars being pushed by a locomotive engine, but you
might think of high amperage as being a series of
train cars like fifteen or twenty being pushed by that

(10:42):
same locomotive engine. In both cases, the locomotive engine is
putting out the same amount of force. It's just that
in one case it's pushing a relatively small number of
train cars and the other one that's pushing a larger number.
But the amount of force it's using for both is
the same. So that's the difference between current and voltage,

(11:03):
or if you prefer amperage and volts. Uh. Now, current
will get a bit more confusing when we start talking
about the direction of flow. And that's thanks to a
certain founding father of the United States. But I don't
want to jump ahead. We'll get there when we get there.
I'll save that for a little bit later in this episode. Finally,

(11:23):
we have the concept of resistance, and as the name suggests,
this is the property of a material to resist the
flow of electric charge. A material with a very high
resistance is an insulator. It does not allow electric charge
to pass through it very easily. You would have to
use a great deal of energy to move an electric
charge through that kind of material. A material with very

(11:44):
low resistance is a conductor. It will allow electric charge
to flow through relatively easily. Now, even conductors have resistance.
You have to get to very low temperatures, like super
frozen temperatures almost close to absolute zero to get to
super conductivity, where you have zero resistance and a conductor

(12:05):
becomes an ideal or perfect conductor. But at other temperatures
there's some resistance. You can get around that by making
a cable thicker. Thin cables have a higher resistance than
thicker cables. But that's kind of beyond what we're talking
about here. We measure resistance in Ohms and Ohm. George Home,

(12:26):
who is a physician who kind of figured all this
stuff out, uh, developed Ohm's law. Now that tells us
that voltage is equal to current times resistance, or you
could say current is equal to voltage divided by resistance,
or that resistance is equal to voltage divided by current.
It's this relationship between current, resistance and voltage that is

(12:49):
inherent in electricity and electronics. Now, those basic concepts are
the very foundation for all electronics. Now, obviously it gets
more comp located. Uh, and you can add in all
sorts of different elements besides that, with like diodes and
things of that nature. But I just wanted to get
that covered as the basis for the conversation that follows.

(13:12):
And now we're going to dive into a history lesson.
So humans have known about electricity in some form for millennia.
Fails of melitas, and I know I mispronouncing that, So
to all my my Greek historians out there, I deeply apologize,
but I have little Latin and less Greek. Along with

(13:33):
my my buddy Shakespeare. Anyway, he had noted that amber,
the material amber, would attract light materials to its surface
after being rubbed. So if you rubbed amber with a
cloth and then held it towards feathers, for example, you
would notice that feathers would have a tendency to be
attracted to the amber. Now, later on we would understand

(13:55):
that this is static electricity, this is building an electrostatic
charge using amber. But this was more of an observation
back in those times and and this centuries before uh
the common era. And in fact, the word electricity comes
from the Latin electron, which in turn comes from the
Greek electron, which means amber. So when we talked about electrons,

(14:19):
that means that's the Greek word for amber. And it's
because of this initial well not even initial, but this
early observation. I just thought that was kind of interesting,
and you would eventually learned that a future engineer. Scientists
named this whole process electricity in honor of this early observation.

(14:43):
Now in nineteen thirty six, we're jumping ahead just to
talk about another discovery about ancient civilizations. There was a
railroad project that ended up excavating some um some ruins
southeast to Baghdad, and they revealed what we have commonly
referred to as the Baghdad batteries. These were vessels that

(15:07):
appeared to have been designed specifically to generate electricity, at
least that's one of the hypotheses about these uh, these vessels.
Some people disagree, but it's a very popular one. Now
you probably have heard about this in some form of
another or another. You may have even seen the MythBusters
episode where they talked about this. The team and MythBusters

(15:29):
talked about the possible applications for these so called batteries,
which could include a thing that you would use in
religious ceremonies where you would have these metal coded vessels
that if you were to touch them, you would create
a circuit and you would allow electricity to flow through
you and that would create a tingling or numbing sensation

(15:49):
in your hands, thus akin to some sort of mystical
experience and thus being part of a religious experience. Or
it could be that it was more of a practical
approach toward something like electro plating, and I thought that
was really cool. So let's talk about what electroplating is,
because otherwise, you know, it doesn't really mean anything to you.

(16:12):
As the name implies, electroplating involves using electricity to cover
or plate one material with another material. Typically you are
plating one type of metal, not necessarily metal, but the
early version of electro plating was metal, but one type
of metal with a more precious metal. So the reason

(16:34):
you might do this is to make really pretty expensive
looking stuff without using too much of the actual precious material.
So you might gold plate a copper bowl, for example,
because you want the gold bowl. Gold is more precious
than copper, but you don't want to actually have to
go out and dig as much gold as you would
need to build a gold bowl, so you want to

(16:56):
plate the copper bowl with gold. That way, it looks
exactly the way you wanted to, but you didn't have
to spend all that time and effort getting all that gold.
In other words, we can thank the laziness and greed
of human beings for some of the early advances as
far as electricity is concerned, So you might want to

(17:16):
use electroplating to do that. We also use electroplating for
other purposes, like putting rust resistant coatings onto stuff that
otherwise would corrode. Uh. You can also use it to
produce alloys like bronze and brass. But let's go back
to electroplating. So let's say these ancient people were using
the so called Bagdad batteries in order to electroplate gold

(17:39):
onto copper. How would you do this well, First you
have to make sure that the copper is totally clean,
because if it has any Schmutz on it, the gold
will not properly adhere to the copper and it'll flake off.
So you typically would clean copper this way by dipping
it in a solution that either is a really powerful

(18:01):
alkaline solution or a very powerful acidic solution to to
truly clean it. Once you did that, you would then
attach a conductor from the battery to the copper that
you're playing on on electroplating. So if it's a bowl,
then you would want to make sure that the terminal,
the proper terminal from the Baghdad battery is in contact

(18:23):
with that copper bowl. Then you would put that whole thing,
the copper bowl with the um the terminal into an
electro light solution, which is in this case a gold
based electro light, so you have gold particles within the
electrolyte itself. Now electrolytes, by the way, our materials that

(18:44):
dissociate into ions when dissolved in a suitable medium and
become a conductor of electricity. So ions, of course, are
are our variations of atoms that have a net charge
on them. They're not neutral. They have either a net
negative or a net positive charge. So when you do this,
you've got your gold ions in this electrolyte solution. You

(19:07):
then put the electrodes together so that not together, but
within the solution, so that a current can pass through
the electrodes. Allow the current to go through the electrolight
into the other terminal or the other electrode, and you've
got a negative in a positive electrode. So when the
current passes through the electro light, the electrolyte splits up

(19:28):
and some of the metal atoms contained within the electrolyte
are deposited on one of the two electrodes that you
inserted into the electrolyte. So what's really happening is the
metal atoms are ions. They hold that charge. They're attracted
to the electrode that has the opposite charge, and they
attached to it. So if you have a negatively charged
terminal and you have positively charged gold ions, that opposite

(19:52):
attract rule still takes place and the gold will plate
onto the copper electrode or bowl in this case, and
then you've got your gold plated copper thing of a
jig which is kind of cool. Now there's some who
put forth the hypothesis that perhaps ancient people has made
other uses of electricity, all the way up to even

(20:14):
powering lights in ancient Egypt, but most scholars that I
have consulted dismiss this as unrealistic. I haven't really seen
much evidence to support this apart from some circumstantial evidence.
Some supporters cite a hieroglyphic relief that shows what to

(20:37):
our modern eyes appears to be an enormous lightbulb, but
the accepted interpretation of that hieroglyph seems to be that
it's a lotus leaf with the figure of a snake
on it, not a huge ancient lightbulb. Still, it seems
that there was at least some knowledge of the existence
of electricity, if not what it actually could do or

(20:57):
what it was. Now that's a trend that would last
for centuries. In fact, we were making use of electricity
well before anyone really knew what was going on with it.
And again, to me, that is one of the phenomenal
things about human history is when we come across these
moments where people have figured out something or how to
use something without really fully understanding why it is that

(21:20):
could be dangerous. Clearly, there were plenty of cases of
that in the nineteen fifties with radiation, where people thought
that radiation didn't have any particular harmful effects. You might
have seen things about like using X rays in shoe
stores so that people could see their feet through the
shoes that they were trying on. And then only later

(21:42):
did we realize that X rays are an ionizing form
of radiation and that we probably should not or definitely
should not have been doing that. Um same sort of
thing with electricity. We were putting it to use before
we ever really understood what was going on there. Uh.
But of course electricity isn't ionizing radiation, so it does
have very different effects then radiation does. But what follows

(22:05):
is a brief history of the developments that unfolded as
very very smart people figured out what the heck electricity is.
So in the fifteen hundreds you had an English physician
and proto scientist named William Gilbert who began to experiment
with magnets and static electricity. So he used loadstone, which
is naturally magnetic iron ore, and he published his work

(22:27):
in sixteen hundred under the title De magnete or a
de magnet magneti. It's magneto but with a knee. He
was able to describe magnetism and static electricity as distinct phenomena,
though he wasn't really sure what was actually causing it.
His hypothesis was that there was some sort of fluid

(22:48):
or humor, as in the various humors of the body.
There was another prevailing physical theory at the time, and
that this was the cause of attraction with static electricity,
and that if you rubbed amber, what you were actually
doing was removing some of that fluid from the amber,
which created a hole or like a vacuum around it,

(23:09):
and this is why light objects would become attracted to
the amber. He called it a fluvium and described it
as an electric effect. In sixteen sixty an inventor named
Otto von Gerrika built a machine using a globe made
of sulfur, and if you rubbed the globe as it turned,

(23:29):
you could build up a charge, an electrostatic charge, causing
it to attract small light objects such as feathers or
scraps of paper. Garrika also observed that his invention would
cause a spark if you rubbed the globe for long enough.
You could then touch something metal like a brass knob
and see a spark fly between the electrostatically charged object

(23:51):
and the grounded piece of metal. Stephen Gray, another English scientist,
observed in seventeen twenty nine that some stuff doesn't can
duct electricity at all. So he thought some materials would
allow the fluid of electricity to flow through and other
materials would hamper the flow of this fluid electricity, which

(24:11):
is sort of true when you get to electrical resistance,
only we're not talking about a fluid really. Later that century,
Dutch inventor's Pietr von Musen book and evolved von Kleist
created what we now call the Layden jar, and there
are actually two variations on basic Layden jars, which store

(24:33):
electrostatic charges. They're essentially capacitors, So you build up an
electric static charge in this thing, and then when you
touch the the charged component, you allow that electro static
charge to discharge to spark um. So they release all
of that charged energy in an instant, unlike a battery,

(24:56):
which releases UH which which creates the voltage difference and
allows for electric electric current to flow over time. A
capacitor releases it in a in a a moment. There
are two basic versions of the Leyden jar, and the
first one uses a metal container inside which you have

(25:18):
a glass vessel nestled inside that metal container, and inside
the glass vessel you have a second metal container nestled
inside that. So it's kind of like a sandwich where
the bread is metal container and the and the meat
inside is glass. I don't recommend eating that sandwich, it
would not taste good and probably hurt you, but it

(25:43):
was that layer metal glass metal, and you would then
also have a rod of metal that would extend up
from the base of that interior lining. So imagine like
a column rising up from that internal metal cup inside
the glass vessel, which in turn is inside a larger
metal vessel. The second variation has a metal vessel filled

(26:07):
with a conductive fluid like water that's got a salt
dissolved in it. Water on in its own will conduct
electricity as long as it has some impurities in it,
but you can make it conduct electricity more effectively by
adding or doping the water with some of those impurities,
and it would have a metal rod sticking out from
the water. Now, both versions would allow you to do
essentially the same thing, which is store up that electro

(26:29):
static charge. And you do this by building up an
electric static charge in something else. So you might take
some amber, for example, and rub the amber. Then you
would bring that into contact with that metal bar that's
extending upward from the jar. That would introduce a charge
to one plate in this capacity, and that would create

(26:52):
the opposite charge in the opposing plate. Uh in this
case that exterior metal casing, you would need to ground
the outer metal case, which you could just do by
touching it yourself, or you could run a wire from
the exterior metal case to the ground or to a
metal pipe. And when you create a pathway between the
two plates by touching the charged rod, it creates a

(27:14):
spark as the charge is able to equalize, and that
could be a significant shock, depending on how much you've
built up inside this laden jar, to the point where
it could really hurt or possibly do serious damage. Both
Klaised and Moose musten Brook had shocking experiences with the
respective laden jars, and neither was really sure exactly what

(27:35):
was happening. Now we've got a lot ward to talk
about with the early discoveries surrounding electricity. But before we
get a charge out of all that, let's take a
quick break to thank our sponsors. All right, we're up

(27:55):
to seventeen fifty two, and that's when we revisit the
the great founding father I had mentioned earlier, Benjamin Franklin.
That's when we got the legendary experiments that Franklin conducted um.
He was friends with a scientist named Peter Collinson over
in Europe, and Collinson had sent Franklin and electricity tube. Franklin,

(28:18):
like his predecessors, thought electricity was a type of fluid,
and he hypothesized that lightning itself was an electric spark,
very much like the kind a latent jar could produce
if you built up enough of an electrostatic charge, and
thus charged forces would cause a lightning strike. And he
further hypothesized that you could use a metal rod to

(28:41):
draw lightning to a specific location, which could end up
saving structures from being struck by lightning. So if you
had a house and it got hit by lightning back
in those days, your house would very much be damaged,
possibly burned down as a result. So he thought, well,
maybe you could draw lightning away using long metal rods.
But problem was he couldn't build a metal rod tall

(29:03):
enough to dwarf the structures. He thought that he was
gonna have to build something that could almost reach the
skies themselves, which made it too big of a challenge.
Uh So he came up with this idea of using
a kite instead. Meanwhile, over in France, Thomas Francois d'allebard

(29:23):
decided to put Franklin's ideas to the test. He actually
constructed a large metal pole to try and conduct electricity
and declared that Franklin was absolutely right that in fact,
that metal rod does draw lightning. But this news didn't
travel back to America that fast. I mean, it took
a really long time for information to go from one
place to another, so Franklin was unaware that his hypothesis

(29:48):
had proven correct. So that same year, Franklin reportedly conducted
his experiment using a silk kite with a key tied
to the silk kite down to the string, and as
legend goes, he flew the kite up during a thunderstorm
until the key drew lightning to it, and then used
that key to charge a laden jar. So the electric

(30:11):
charge and the key was then transferred to a laden jar,
which again holds electrostatic charge. Now, I say reportedly because
Franklin's writings never outright said that that was what happened.
He never specifically said that he himself had performed the experiment. Now,
he did say that he did a simplified version of
this plan and that it happened in Philadelphia, But it's

(30:32):
unclear who was actually flying the kite at the time.
And according to modern scientists, if Franklin had conducted the
experiment as it has generally been reported, Franklin would have
been toasted. He would have been fried scientifically speaking. So
the general theory about this not scientific theory, but you know,
the general idea of what actually happened was that Franklin,

(30:55):
if he conducted the experiment at all, was able to
pick up an electrostatic charge by flying the kite near
a storm, but that the kite was never directly struck
by lightning. It just rather picked up a charge by
being lightning adjacent. I guess you could say, all quibbling aside.
By this time, it became established that lightning was in
fact a really big spark. Therefore, part of this concept

(31:19):
of electricity. Franklin made practical use out of this knowledge
by inventing the lightning rod. Now, the purpose of a
lightning rod is to attract a bolt of lightning to
the rod and then channel the electricity down to the ground.
Uh This spares structures from being hit by lightning and
thus being damaged. So your lightning rod typically has a
metal cable that extends down from the rod and then

(31:42):
is bury. It has like a conductive steak as well
that's buried in the ground and that channels the the
the current from the lightning down into the ground. Or
really it just gives the current a different direction to travel, honestly,
but if you look at lightning, current goes from the
ground up to the sky. It doesn't matter. The point
being that he was able to figure out a way

(32:03):
of sparing houses by using lightning rods. So he also
established something about electricity that vexes folks when they're first
learning about it. Franklin established electricity is having two natures.
He called it the resinous electricity, which he viewed as
a dip in the electric fluid from the normal amount

(32:24):
and thus negative. So this is where the charge is
flowing too. This would be akin to that idea of
a vacuum. You have a lack of something a hole,
and thus something else goes to fill the whole. Then
there was what he called vitreous electricity, which was an
excess of electric fluid and thus a positive amount. So

(32:44):
Franklin said, the movement of electricity goes from positive to negative.
You have an overabundance of this electric fluid, and it
moves to where you have a deficiency of electric fluid.
So the this is somewhat confusing if you're looking at
the scientific description of what's happening with your basic electric circuit,

(33:08):
where you're having negatively charged particles, that is, electrons go
from an area of high concentration to an area of
low concentration. It's the it's going from negative to positive,
not positive to negative. But it's because you're looking at
two different definitions of what is positive and what is negative.
That's where the real confusion lies. Uh So, when we

(33:29):
talk about electronics and we talk about electron flow and
we're looking at it purely from a charge perspective, we're
looking at negative particles moving towards a positive side. But
let's make it even more confusing than that. There are
really two major ways to illustrate charge flow in circuits.

(33:49):
One of them is called conventional flow notation, which is
the way electrical engineers tend to describe electrical flow, and
this follows Franklin's approach. It goes from positive to negative,
so electricity flows from the positive terminal to the negative
terminal because we're talking about the surplus of electrons to

(34:10):
the deficiency of electrons. We're not talking about the the
electric charge, we're talking about the number. There's more electrons
over here than they're over there, so that's why this
is gonna be the positive terminal with more electrons and
the negative terminal has fewer electrons because we're talking about
surplus and deficiency. But there's also electron flow notation now

(34:32):
that one looks at the actual charges, not the numbers.
So in that case, the negative terminal is where the
electrons are and it flows to the positive terminal. Both
illustrations can describe the exact same circuit, but they're going
to show a difference in what is positive and negative terminals,
and so it can get really confusing. Uh. Engineers tend

(34:54):
to use that conventional flow notation. Professional scientists tend to
prefer the electron flow notation, and thus we're all left
scratching our heads. All that being said, an enlightened person
might argue that Franklin's description is perfectly suitable if we
look at other examples of electric charge moving across an area,
Because yes, in wires, we're talking about those negatively charged electrons,

(35:15):
but in other substances you might talk about protons or
positively charged ions moving due to a difference in charge.
And because you have these positively charged ions or even
sub atomic particles and their movement can also be described
as electricity. It it's perfectly valid. It's just not what
we see with electronic circuits. So there's that. Still a

(35:39):
lot of folks bemoan the fact that Franklin's decision to
name things as he did was kind of based on
a whim and it made things more complicated as we
learned more later on. But honestly, there was no way
for him to know at the time. It's not really
his fault. It just kind of turned out that way. Anyway,
back to the timeline, since we won't learn about electrons

(36:00):
or a couple of hundred years after Benjamin Franklin's work
with lightning, we should just go back to what people
were experimenting with and learning about. So a few decades
after Franklin's experiments, there was a guy named Charles Augustine
de Colombe who made some significant contributions to our understanding
of electricity. He published multiple papers on the subjects of

(36:23):
electricity and magnetism between seventeen eighty five and seventeen ninety one,
and he had done a lot of work leading up
to those publications. Among his discoveries was the relationship between
the strength of opposite charges and that distance between them.
He developed what we now call Coulomb's law. Now, this
law states the electrical or magnetic force depends upon the

(36:45):
strength and nature of the charges of the two objects
and the distance between those two objects. So, if you
have two similarly charged objects, like two positives, they repel
one another with a non contact force. To opposite charged
objects a negative and a positive will attract one another
with a non contact force. These forces are vector quantities,

(37:10):
which means they have both a magnitude and a direction,
and the distance between the two objects affects the amount
of force. The closer the objects are to one another,
the greater the force is between them, or in other words,
that the magnitude of the electrosthetic force of attraction between
two point charges is directly proportional to the product of

(37:31):
the magnitudes of charges and inversely proportional to the square
of the distance between them. That's the technical description of
Coulomb's law. There's also a constant that you have to
use when you're working with equations using Coulomb's law, but
we don't need to really dive into that, the point
being that he realized that distance definitely plays a factor

(37:54):
with these other forces that we still didn't fully understand
at that point. Then you have Alessandro Volta, from whom
we get the word volt He was an Italian physicist
who became interested in the study of electricity. Now we
normally credit Volta with the invention of the electric battery,
those Baghdad batteries set aside. He began by building on

(38:15):
the work of another physicist named Johann Carl Vilk, who
had invented the electro forests. The electro forest was a
simple capacitive generator that could build up an electrostatic charge
for use and experiments. So all these scientists really wanted
to study electricity. But to do that you had to
build up these electrostatic charges so that when you discharge them,

(38:37):
you had something to study. So this was a guy
who had developed the electro forests as a way of
making that easier to do. Um Volta's buddy Luigi Galvani
had observed something really unusual himself. He noted that when
he used two different types of metal to make contact
with the muscle of a frog, an electric current would

(38:58):
pass between the two, and so he thought the source
of the electricity was from the frog itself, and he
called it animal electricity. Volta disagreed, saying that the frog
was just a conductor, not the generator, and so he
was calling it metallic electricity. And this was a big
debate in circles at the time. So in Volta began

(39:19):
to experiment on metals used, often using his own tongue
as the laboratory. He would put two different discs of
metal on his tongue and feel the tingling on his
tongue and say, yep, there's there's an electric current passing there.
But he could also use other stuff as well, and
he was able to observe that in fact, it was
the metals that were important, not the creature. This also

(39:41):
inspired Volta to look into electricity further, which culminated with
the design of the first real battery as far as
modern science is concerned. It was an eighteen hundred that
Volta invented the voltaic pile, also known as the voltaic column.
This battery consisted of alternating layers of zinc and silver,

(40:02):
or of alternating layers of copper and pewter, with layers
of paper or cloth soaked in a salt solution in
between the different metal disks. This arrangement could create a
steady electric current that didn't need recharging like a Leyden
jar did, so this was a great solution for engineers
and scientists who wanted to be able to work with electricity,

(40:23):
but didn't want to have to stop every time they
discharged Leyden jar to build up another electrostatic charge. This
was a a steady source, so it was a huge boon.
Although he didn't really have any other practical applications for
electricity just yet. But six weeks after Volta published his findings,
English scientists William Nicholson and Anthony Carlyle experimented with a

(40:47):
voltaic pile and electrodes placed in water, and the electric
current that passed through the water caused the water to
decompose into hydrogen and oxygen, breaking the molecules of water
apart art. And this is a process that we call electrolysis,
specifically with water, but with other things as well, using
electrical electrical charges to break those molecular bonds. By eighteen

(41:11):
o two, William Crookshank had designed the first electric battery
for mass production, using copper and zinc in a wooden
box filled with an electrolyte of brine and sealed to
prevent leaking. So a big think of a big wooden
battery akin to something like a car battery would be
like this today. So Volta died in eighty seven, and

(41:34):
it was an eighty one that the scientific community decided
to name the unit of electromotive force the vault, after him,
so he was. He did not live to see his
name used to describe electromotive force, but he certainly was
the inspiration for it, and other inventors and scientists would
improve upon Volta's design, including chemist John F. Daniel and

(41:57):
later a physician from France named Gaston p Ande, who
designed the first rechargeable lead acid battery. So Plante's design
is the basis for modern lead acid batteries today, like
the kind you would find in internal combustion engine vehicles.
That has its roots back in the early, well early
to mid nineteenth century. It's kind of incredible. Later on

(42:20):
you would see other improvements with battery technology. Might as
well stick with that for right now. That would include
the nickel cadmium battery, which was first designed by Valdemar
Jongner from Sweden in eight and the nickel iron battery
designed by Thomas Edison, or at least Thomas Edison's team
of engineers and scientists. There's always a caveat whenever you

(42:43):
say Thomas Edison's invention, because he had a whole lot
of people working for him who were busy research in
developing all sorts of different technologies, and Edison's name gets
attached to a lot of it. Edison himself was a
brilliant guy, uh but he larged. He was brilliant in
bringing people to work on these cool ideas, um sometimes

(43:05):
contributing to him directly. Sometimes he wasn't, but he was
providing the space for that kind of work to happen anyway.
He helped develop the first nickel iron battery in nineteen
o one. But I've talked a lot about batteries, so
what I'll do in the next section is talk about
other developments in electricity. But before I jump into that,

(43:27):
let's take another quick break to thank our sponsor. So
one of Volta's contemporaries was Andre Marie Ampere. We talked
about amps and amperage. It comes from Ampaire, so his

(43:48):
name also serves as a type of scientific unit, basically
one describing current as opposed to voltage. And Pierre noted
in eighteen twenty that a wire carrying an electric cur
was sometimes attracted to and other times repelled by other
such wires. So he was starting to notice this magnetic
attraction along current carrying wires, and in eighteen thirty one,

(44:13):
another fellow, Michael Faraday, explored this idea further, and he
discovered that if he revolved a copper disc inside a
strong magnetic field, it would generate an electric current inside
the copper disk. Faraday and a guy named Humphrey Davy
would later build an early electric generator using this discovery.

(44:34):
The generator consisted of a coil of copper that would
be moved past a magnet. And this is the very
very rough basic idea for electric generators today. Moving a
conductor through a magnetic field induces electricity to flow through
the conductor. That's the simplified version. Now more specifically, the
greatest current flows through a conductor when the conductor is

(44:57):
moving through the most lines of magnetic flux at it
the fastest rate. So magnetic flux is a magnetic field
passing through a surface. You've probably seen illustrations of magnetic fields.
Imagine a bar magnet. It's just a simple rectangle. You
have a north pole of the bar magnet and a

(45:17):
south pole of the bar magnet. You would draw lines
extending outward from the north pole. These lines would start
to loop back down towards the south pole in ever
increasing but less strong uh magnetic lines that go further
out until you get a couple that don't even loop
back down to the south pole. They just go outward.

(45:40):
So lines extend out from the north pole and go
into the south pole, and you designate this by drawing
little arrows on the lines to show the direction of this.
The vector quality of this at the south pole you've
got all those incoming lines, including a couple from apparently
external sources. When you look at the illustrations of magnetic fields,

(46:04):
so if you move a conductor through these magnetic fields,
it sort of breaks those lines. It moves through those
those lines of magnetic force um and you do it quickly,
current will flow through the conductor. It induces current to flow,
and the most current will flow when the conductor moves
through the ninety degree perpendicular plane with respect to the

(46:28):
magnetic field. So again, if you've got let's imagine that
the conductor is a a square. We've got a square
of copper. It's it's not solid copper. It's just a
copper wire that's been shaped in the form of a square.
It's got two prongs at the base of it that
go down to where there's a crank. So I can

(46:49):
turn the crank and this will rotate the square. Right now,
let's say to either side of the square, I put
two very powerful magnets. One of them has the north
goal facing into the gap. The other one has its
south pole facing into the gap. The squares in the
center in between these two magnets. When I turned the

(47:11):
square so that it is perpendicular to the magnetic field
extending out from these magnets. That is the moment when
it's going to have the most current flowing through the
square as it as it moves. It has to be
moving for this to really work. When you get it
parallel with the magnetic fields, you will have the least

(47:33):
amount of current. In fact, you have no current at
all flowing through it at that moment. If you keep
it turning, then you will be able to generate current
h fairly consistently. It does actually pulse, it's not it's
not steady. If you were to measure it out, you
would actually see it pulsing. And only does it pulse,

(47:55):
the direction of current will change. Uh, so it's actually
alternating current. But we'll talk about that again in a
little bit more a little bit later to really get
into alternating current. Because in eighteen thirty two there was
a French inventor named Pixie p I x I I M.

(48:16):
Hippolyte Pixie or Hippolyta if you prefer, But he built
an electrical generator based off of Faraday's discoveries that was
very similar to what I just described. Had these permanent
magnets that had a rotating conductor, that would um actually
really had a spinning magnet and a steady conductor. But
same same principle. Right, you've got a spinning magnet and

(48:39):
a steady conductor. You could rearrange that as a spinning
conductor in a steady magnet. Doesn't really matter. He found
that the current direction changed each time the north pole
passed over the coil after the south pole had passed
over the coil. And this was an early alternating current generator,
but there was no real use for alternating current at

(48:59):
that time, so and Here advised Pixie to design a
generator with a device known as a commutator. Commutators are
meant to change alternating current to direct current. So the
difference between alternating current and direct current is alternating current
changes the direction of the current. So you have electrons

(49:19):
flowing through a circuit in one direction, and then they
will reverse and flow into the other direction with alternating current,
and they do this many times every second. Then you
have direct current, where the direction of flow is always
the same. It goes from if you're doing the conventional

(49:41):
flow diagram, it goes from the positive terminal to the
negative terminal and it's never gonna change. It's always gonna
follow that batteries give off direct current. Power plants that
use a C generators give off a C current. And
I'll talk more about that in part two. But why
do generators create alternating current? And how do commutators work? Well,
remember that example I just gave. You've got this square

(50:03):
rotating conductor copper wire. It's in between the two magnets. Uh.
Let's say that you've got your square position between the
south pole of one magnet the north pole of the
other magnet. And at the moment you're holding the square
steady between the two magnets, and you put put a
piece of blue tape on the side that's facing magnet

(50:23):
number one, which has the south pole facing into the gap,
and you put a piece of red tape on the
side facing magnet two, which is the north pole of
the other magnet. And then you rotate the square so
that it moves down or back with respect to magnet one,
and up or forward with respect to magnet two. So

(50:44):
if you're staring at this, you see that blue tape
start to move down. Let's say that we've got this
horizontally aligned. It appears to move down with respect to
the magnets. The red tape moves up with respect to
the magnets, and as it does, this induces current to
flow in one direction in the copper wire. But once

(51:04):
the square hits that parallel position with the magnetic fields
and then continues its turn, the side that was going
up is now going down through a magnetic field, and
the side that was going down through a magnetic field
is now going up through a magnetic field. So the
red tape takes this turn starts moving downward. The red
blue tape is making its turn and moving upward, and

(51:25):
at that moment, when the conductor breaks that parallel plane,
the current reverses direction. Turning the conductor quickly will induce
more current to flow and increase the number of cycles
the current flow reverses per given unit of time. Now,
as I said, this is alternating current, but the early
experiments for the day, they really needed direct current, not

(51:46):
alternating current, which means you have to find a way
to make the current flow stable in a single direction,
and that's where a commutator comes in. A simple commutator
is a split ring where the two sides of the
ring are made up of conductive material, but they're insulated
from each other with an insulating material in between them.

(52:06):
So imagine a ring that has one tiny sliver cut
out of the ring, so it's like two halves of
a ring, and then you have an insulator in between
the two halves. On either side of this uh split ring,
you have elements that we call brushes. These are just
conductive materials that are stationary contacts. They make contact with

(52:31):
this rotating split ring. So as the conductor turns, so
does the split ring. And while the direction of current
changes within the conductor, the nature of the split ring
makes the flow of current and the overall circuit unidirectional.
Now I realized this is really difficult to visualize without help,
so I actually recommend that you go look up videos

(52:51):
about d C generators to get a better idea of
what I'm talking about. Because a DC generator, and it's
most basic level, is really an a C generator with
a commutator attached to it. The important thing note is
that the basic generator makes al dre and current and
the commutator makes it into direct current. Now, at this stage,

(53:13):
electricity was still something scientists and engineers would experiment with
they still didn't have any real practical uses for electricity
right now, not on a massive scale at any rate.
But over the course of the nineteenth century, it became
clear that electricity had the potential. It's another electricity pun
for you to change the world. So in our next episode,

(53:35):
we're gonna look at the discovery of the actual electron,
which happened at the very tail end of the nineteenth century.
We'll talk about the atomic physics involved in electricity. We'll
also talk about d C versus a C as far
as the current wars were concerned, and Edison versus Tesla
and why Edison versus Tesla is really an oversimplification of

(53:55):
that actual battle. And we'll talk about the rise of
power grids and the various methods that we use to
actually generate electricity, from coal plants to nuclear reactors. In
the meantime, if you guys have any suggestions for future
episodes of tech Stuff, I recommend you get in touch
with me. My email address is text stuff at how
stuff Works dot com, or you can drop me a

(54:17):
line on Twitter or Facebook. The handle for the show
at both of those is text Stuff H s W.
As always, I'm happy to hear any suggestions you might have,
whether it's a topic for a show or a guest
I should have on the show, Get in touch with
me and let me know. Also, remember you can watch
me record these things live on Twitch. Just go to

(54:39):
twitch dot tv slash tech stuff to see the schedule.
And I hope I will see you guys in there
because it's a fun time and you get to talk
to me a lot while I record these things. And meanwhile,
I'll talk to you guys again really soon. For more

(54:59):
on us and thousands of other topics is at how
stuff works dot com.