Speaker 1: Welcome to Tech Stuff, a production of I Heart Radios
Speaker 1: How Stuff Works. Hey there, and welcome to tech Stuff.
Speaker 1: I'm your host, Jonathan Strickland. I'm an executive producer with
Speaker 1: I Heart Radio and I love all things tech and
Speaker 1: in a recent episode, I talked about how scientists, doctors,
Speaker 1: and philosophers had experimented with using the direct application of
Speaker 1: electricity in an effort to treat various medical conditions. In
Speaker 1: this episode, we're going to take a further step back
Speaker 1: to understand the basics behind electricity itself. A lot of
Speaker 1: this is going to be a refresher course from science classes,
Speaker 1: primarily in physics, but it's to cover stuff that often
Speaker 1: confuses people, and I'm including myself in that category. I
Speaker 1: often get confused to the point where I frequently have
Speaker 1: to do a quick refresher. So I'm not a scientist,
Speaker 1: I'm not an electrical engineer. I have to remind myself
Speaker 1: on the basics whenever I talk about electricity. Complicating matters
Speaker 1: is that many text books for younger students in particular,
Speaker 1: frame electricity in ways that can be misleading. They oversimplify
Speaker 1: ideas to the point where they're kind of, you know, wrong,
Speaker 1: and I know I've been guilty of doing the same
Speaker 1: thing on this show. After all, I am a product
Speaker 1: of the educational system that relies on such textbooks, and
Speaker 1: I didn't have a background and electrical engineering. I know
Speaker 1: I have on many occasions described electricity as the flow
Speaker 1: of electrons, and that's not really the case. Now. Electrons
Speaker 1: are charged sub atomic particles. They carry an electric charge.
Speaker 1: But electricity, a vague term at best, isn't about these
Speaker 1: carrier particles. It's more about the electric charge itself. So
Speaker 1: I have to actually unlearn what I had learned to
Speaker 1: talk about this more accurately. So if you're like me,
Speaker 1: then this episode is going to be great for you.
Speaker 1: And if you already know electricity inside and out, you'll
Speaker 1: probably find this episode a little too basic for your liking.
Speaker 1: Or in a worst case scenario, you might hear me
Speaker 1: get something totally wrong. I'm working hard to prevent that,
Speaker 1: but I am human. So if I say something totally wrong,
Speaker 1: feel free to call me out on it, but please
Speaker 1: just be nice about it. I am well intentioned, and
Speaker 1: if I make a mistake, I want to correct it.
Speaker 1: Just don't drag me under the bus for it, all right,
Speaker 1: So Let's assume some of you out there are like
Speaker 1: me and you don't have a background in working with electricity.
Speaker 1: Let's figure out why this is so confusing. I mean,
Speaker 1: we do have different units of measurement all to describe
Speaker 1: various components of electricity and the behavior of electrical phenomena.
Speaker 1: You know, we have whats, we have what hours or
Speaker 1: more frequently, actually, really we have kill a lot hours.
Speaker 1: We have volts, we have amps, we have ohms. It
Speaker 1: can get a little overwhelming, so I'm gonna do my
Speaker 1: best to try and clear stuff up a bit now.
Speaker 1: In that medical history episode, I talked about Greek philosophers
Speaker 1: who observed the effects of static electricity, what we call
Speaker 1: static electricity, where you build up an electric charge and
Speaker 1: it can be discharged when you come into contact with
Speaker 1: something else, and about how Benjamin Franklin proved that this
Speaker 1: was the same stuff as was found in lightning. But
Speaker 1: I mostly stayed away from the history of detecting and
Speaker 1: measuring electrical phenomena and the terminology that we associate with it.
Speaker 1: So that's really what this episode will end up being about.
Speaker 1: And in that previous episode, I mentioned that Benjamin Franklin
Speaker 1: thought of electricity as a sort of fluid. He was
Speaker 1: not alone in this. It was a prevalent thought at
Speaker 1: the time, and that's probably why he described the movement
Speaker 1: of electricity as current. But the way Franklin described current
Speaker 1: and the way we tiply talk about electricity has caused
Speaker 1: confusion for some folks like me. So I'll explain. Imagine
Speaker 1: you have two pools of water and they're connected by
Speaker 1: a hose. Now imagine that the ground is perfectly level
Speaker 1: between these two pools of water. You would expect the
Speaker 1: water in the hose to be pretty much in a
Speaker 1: state of equilibrium. It would be still. But imagine one
Speaker 1: pool is at a slightly higher elevation than the other. Well,
Speaker 1: then you would expect water to follow the force of
Speaker 1: gravity and flow down through the hose into the other pool.
Speaker 1: You would have a current, and you could think of
Speaker 1: the pool at the higher elevation as being positive, at
Speaker 1: least in terms of elevation. So in that context, you'd
Speaker 1: say that a current of water is flowing from positive
Speaker 1: to negative through the hose. Now I'm oversimplifying a bit,
Speaker 1: but that's kind of what Franklin was thinking. When it
Speaker 1: comes to the fluid. He observed with electricity. He described
Speaker 1: current as moving from positive to negative, and this has
Speaker 1: more to do with the electrostatic experiments he was doing
Speaker 1: and whether or not the surface that he was rubbing with,
Speaker 1: for for example, was the positive or whether it was
Speaker 1: the negative. You also have to remember that Franklin made
Speaker 1: his observations more than a century before we had discovered
Speaker 1: that electrons are even a thing that exists. I have
Speaker 1: often joked that Franklin really messed us all up with
Speaker 1: his description of current going from positive to negative, but
Speaker 1: turns out that's not really true. Now explain why that
Speaker 1: is in just a moment. Now, Later on after Benjamin
Speaker 1: Franklin's time, we would learn more about electricity and we
Speaker 1: began to learn about electric charges and electric potential. We
Speaker 1: began to understand that you can have different magnitudes of
Speaker 1: electric charge and it could be negative, it could be positive,
Speaker 1: and that you can create a connection between different things
Speaker 1: with different electric charges and observe of a flow of
Speaker 1: electric charge or an electric current. This was all stuff
Speaker 1: that we learned over time. And let's think back on
Speaker 1: our two pools connected by a hose analogy. If we
Speaker 1: had two pools that were on level ground and we
Speaker 1: equated that with a conductive pathway in an electrical circuit.
Speaker 1: Let's just say it's a it's a copper wire connecting
Speaker 1: two terminals. Then we would describe that wires having equal
Speaker 1: amounts of potential on either side. There's not a positive
Speaker 1: and a negative terminal, they're both neutral, and in other words,
Speaker 1: there's no difference in electrical potential. There's no difference in
Speaker 1: potential energy, there's no flow of electrical charge, and thus
Speaker 1: no electrical current. In the analogy in which we think
Speaker 1: of one pool being at a higher elevation than the other,
Speaker 1: we would describe the corresponding electrical system as the end
Speaker 1: of the wire representing the elevator pool, elevator pool having
Speaker 1: a higher potential energy or just higher potential, and the
Speaker 1: lower end having a lower potential energy or lower potential,
Speaker 1: And we call this difference an electric potential between the
Speaker 1: high and the low pools as the voltage. So the
Speaker 1: greater the difference between those two points in the analogy,
Speaker 1: the greater difference in an elevation would mean the greater
Speaker 1: the voltage. So if you have one that is one
Speaker 1: terminal that's extremely positively charged and one that's extremely negatively charged,
Speaker 1: you have an extreme voltage. The difference between those two.
Speaker 1: Sticking with the analogy of water, voltage is like water pressure.
Speaker 1: It's kind of how hard the electricity is being pushed
Speaker 1: through the conductive connection between the different terminals. So if
Speaker 1: the electric potential is of great magnitude, you get more pressure.
Speaker 1: It's like a water hose shooting out water at high force,
Speaker 1: like a fire hose connected to a fire hydrant. If
Speaker 1: the electric potential isn't that great, if if the difference
Speaker 1: isn't that great, then the voltage is lower, and in
Speaker 1: our analogy, the water pressure is lower, so water would
Speaker 1: come out and kind of a lazy arc as opposed
Speaker 1: to blasting out at full force. And it helps if
Speaker 1: we remember that opposite charges attract each other and like
Speaker 1: charges repel each other. So if there's a big difference
Speaker 1: in electrical potential between two connected points, the like charges
Speaker 1: are going to want to rush over to the opposite
Speaker 1: charges and get the heck away from the other like charges.
Speaker 1: If you listen to my previous episode, then you heard
Speaker 1: me talk about Alessandro Volta, the man who invented the
Speaker 1: voltaic pile, which was a precursor to the modern battery.
Speaker 1: He did that back in eighteen hundred. It's from his
Speaker 1: name that we get volts and voltage, and a volt
Speaker 1: is a unit of measurement to describe the difference in
Speaker 1: electric potential between two points. I'll get back to describing
Speaker 1: exactly how we define volts in a second, because unfortunately
Speaker 1: that definition depends upon us knowing what some of this
Speaker 1: other stuff is. First. It doesn't do you much good
Speaker 1: to give a definition if you realize that all the
Speaker 1: other terms in that definition are undefined. Okay, So if
Speaker 1: we assume voltage is pressure water amps, Now, amps are
Speaker 1: a measure of current, or how much electrical charge is
Speaker 1: flowing through a specific point in a circuit per unit
Speaker 1: of time. So let's go back to the water analogy
Speaker 1: and change things up a bit. Imagine that we have
Speaker 1: those sets of pools we've been talking about. We have
Speaker 1: one pool at a higher elevation and one pool at
Speaker 1: a lower elevation. Now let's say that we copy that.
Speaker 1: So now we've got to we've got two pools at
Speaker 1: high elevation, two pools at low elevation. With one of
Speaker 1: the high low sets, we connect the two pools with
Speaker 1: an ordinary garden hose, and with the other set, we
Speaker 1: connect the two with a concrete tube with a much
Speaker 1: greater diameter than the garden hose, more water will be
Speaker 1: able to flow through a given point, Let's say it's
Speaker 1: the midpoint of the concrete tube per unit of time
Speaker 1: than through the midpoint of the garden hose in that
Speaker 1: same unit of time. The concrete tube has a greater capacity,
Speaker 1: The tube can hold more volume, and thus we get
Speaker 1: more water coming out per unit of time than we
Speaker 1: would observe with the hose. Well, with electrical circuits, we
Speaker 1: described the same idea with amps. Amps tell us how
Speaker 1: much electrical charge passes a given point in a circuit
Speaker 1: per unit of time. So voltage is the pressure and
Speaker 1: amps or current is the amount of charge. Multiply those
Speaker 1: two together and you get what's now. Moving back to Franklin,
Speaker 1: we'll get back to Watson a second. He thought of
Speaker 1: electricity as a positive flow, that the direction of current
Speaker 1: was in the direction of an electrical field, and unfortunately
Speaker 1: we would later learn that it's the negatively charged electrons,
Speaker 1: not the positively charged protons, that really move around in
Speaker 1: a typical electric circuit. So if we follow the conventional
Speaker 1: explanation of current. The flow of current is in the
Speaker 1: opposite direction of the flow of electrons. In a circuit
Speaker 1: with a battery, we would see movement described as the
Speaker 1: electrons going from the negative terminal of the battery through
Speaker 1: a circuit doing whatever work was part of that circuit,
Speaker 1: like lighting a lamp or something before journeying to the
Speaker 1: positive terminal of the battery. But we would describe the
Speaker 1: current in that circuit as traveling from the positive end
Speaker 1: of the battery through the circuit until it got to
Speaker 1: the negative end. But what's more important here is not
Speaker 1: the carrier of the electric charge. It's the concept of
Speaker 1: electrical charge itself, not the movement of electrons, which again
Speaker 1: are just the carriers. Electricity ultimately is about the flow
Speaker 1: of electric charge, positive or negative. So in our day
Speaker 1: to day use of electricity, we're talking about of the
Speaker 1: type where electrons flow through circuits, so we typically are
Speaker 1: looking at negatively charged particles moving in a conductive pathway,
Speaker 1: pushing that negative charge in the opposite direction of what
Speaker 1: we would typically call the current. But electricity isn't the
Speaker 1: movement of electrons, even though that's often how it is simplified.
Speaker 1: It's really the movement of the charge itself we need
Speaker 1: to be concerned with. And if you have a flow
Speaker 1: of protons, you would still have a flow of charge,
Speaker 1: and thus you would still have electricity. So a particle accelerator,
Speaker 1: for example, the accelerates a beam of protons is creating
Speaker 1: a flow of electricity. Electrons are not even involved in that.
Speaker 1: It's the movement of positively charged particles. You're getting a
Speaker 1: movement of a positive charge that is technically electricity. So
Speaker 1: again we need to kind of divorce ourselves from the
Speaker 1: idea of electrons and think more about electrical charge. The
Speaker 1: electrons happen to be the carriers of that, but that's
Speaker 1: as far as their importance is concerned from this perspective.
Speaker 1: They get important again once we start talking about quantum effects,
Speaker 1: but that's a discussion for a different time. So I
Speaker 1: say all this in order to exonerate Benjamin Franklin a
Speaker 1: little bit. I give him a hard time, but it's
Speaker 1: largely because the way we harness electricity for most of
Speaker 1: the stuff we do means that we have an apparent
Speaker 1: contradiction in the sense of the flow of electrons and
Speaker 1: the flow of current. But to be fair, our lay
Speaker 1: understanding of electricity is based on a lot of misconceptions.
Speaker 1: In general, we focus a bit too much on those
Speaker 1: carrier particles and not the larger concept of electric charge.
Speaker 1: Another misconception has to do with the wires in a circuit.
Speaker 1: I'll explain more after we take a short break. Okay,
Speaker 1: so let's get another misconception out of the way. Many
Speaker 1: people take that analogy of water pipes or hoses or
Speaker 1: tubes as being a literal one to one with electricity,
Speaker 1: and thus the wires in a circuit they think of
Speaker 1: as empty conduits through which electrons can travel like. They're
Speaker 1: imagining the wires as being these hollow tubes, and electrons
Speaker 1: are just shooting down the tubes. They're coming out of
Speaker 1: the battery or out of the wall if you have
Speaker 1: something plugged in, shooting down the tube and getting to
Speaker 1: the other end. But if we think about that for
Speaker 1: even a moment, we realize that cannot possibly be true,
Speaker 1: because the wires themselves are made up of atoms, and
Speaker 1: atoms have electrons. So it's more like a tube or
Speaker 1: a hose or whatever that is already packed with water
Speaker 1: before you connected to the two pools. And even that
Speaker 1: is not a perfect analogy. So let's talk about conductivity.
Speaker 1: Some types of atoms have electrons in their outer energy
Speaker 1: levels that are more lucy goosey. If you have a
Speaker 1: single copper atom, then you've got a nucleus that contains
Speaker 1: twenty nine protons and thirty five neutrons. Now we're talking
Speaker 1: about a basic neutral copper atom, meaning the positive and
Speaker 1: negative charges cancel each other out. So we have twenty
Speaker 1: nine electrons paired up with that nucleus that has twenty
Speaker 1: nine protons. Electrons orbit the nucleus, but not in the
Speaker 1: same way that planets orbit stars or moons orbit planets.
Speaker 1: The electrons inhabit various orbitals, which in turn are in
Speaker 1: what we would call subshells, which are in shells around
Speaker 1: the nucleus. Now I'm not going to dive into all
Speaker 1: of that, because I'm sure most of you have a
Speaker 1: general handle on it. But the twenty nine electrons and
Speaker 1: copper add up to a point where one electron is
Speaker 1: left orbiting the outermost shell. There's no room for that
Speaker 1: last electron in any of the lower shells closer to
Speaker 1: the nucleus, so this electron is pushed out to the
Speaker 1: next lowest energy shell, and it's they're all by its lonesome.
Speaker 1: That means that electron is easier to push around than
Speaker 1: the ones that are locked in packed closer to the nucleus.
Speaker 1: So when you lump a bunch of copper atoms together,
Speaker 1: like that was just one copper atom, right, If we
Speaker 1: put a bunch of copper atoms together and we've got
Speaker 1: something like a copper wire that's made up of trillions
Speaker 1: of these atoms, you end up with a mass of
Speaker 1: copper atoms that all have these single free electrons, and
Speaker 1: you can almost think of those electrons as moving around
Speaker 1: the mass of copper atoms as opposed to being tied
Speaker 1: down to a single copper nucleus. If you then connect
Speaker 1: the wire into a circuit in which you have a
Speaker 1: battery or some sort of generator or something, that battery
Speaker 1: or generator acts as a pump that can push those
Speaker 1: free electrons around. The negative terminal has a charge that
Speaker 1: pushes against those electrons because remember like charge repels like,
Speaker 1: so each of those electrons has its own negative charge
Speaker 1: and pushes further down the path of the circuit. And
Speaker 1: since since the other end of the battery has a
Speaker 1: positive terminal, the negative charges get attracted to the positive side.
Speaker 1: It's not that electrons are shooting out of a battery
Speaker 1: down a pipe, doing some work, and then going into
Speaker 1: the other end of the battery. Is that the charge
Speaker 1: of the battery is pushing through this pathway and the
Speaker 1: electrons carry that charge. Likewise, the electrons are not moving
Speaker 1: at the speed of light. I know I've been guilty
Speaker 1: of saying that before too, but that's not correct. The
Speaker 1: electrons move much more slowly than the speed of light.
Speaker 1: You could even say the charge moves more slowly than that.
Speaker 1: But within the circuit, the charge is moving throughout all
Speaker 1: parts of the circuit at the same time. It's not
Speaker 1: like one electron moves and then the next one and
Speaker 1: then the next one. It's like they're all moving together
Speaker 1: in in lock step. And so you have this entire
Speaker 1: circuit that all goes into motion at the same time.
Speaker 1: And to us that means that we see practically instantaneous results.
Speaker 1: So if you flip on a light switch to an
Speaker 1: incandescent lamp, the light comes on immediately, it doesn't delay.
Speaker 1: That's why. It's because all of those electrons in the
Speaker 1: circuit are moving at the same time, so the effect
Speaker 1: is that it's moving at the speed of light. But
Speaker 1: in reality, what's actually happening is the electrons as a
Speaker 1: whole in this circuit are all moving together. So a
Speaker 1: battery connected to a circuit is not really a source
Speaker 1: of electrons. It's a source of energy. It's providing the
Speaker 1: energy or the pressure to move that charge through the circuit.
Speaker 1: It's the source of voltage. An electrochemical reaction in the
Speaker 1: battery acts as an internal circuit to create this voltage,
Speaker 1: which manifests as a difference in electrical potential shold between
Speaker 1: the positive and the negative terminals on the battery. Connecting
Speaker 1: that battery to a circuit is what gives the energy
Speaker 1: necessary to move this charge through the circuit and to
Speaker 1: do whatever work it is you need to do along
Speaker 1: the way, such as lighting up that light bulb. Within
Speaker 1: a battery, you've got an exothermic reaction that is working
Speaker 1: against the electric field. So it's kind of like pushing
Speaker 1: a boulder uphill. The force of gravity in that case
Speaker 1: would be working against you and you have to overcome it.
Speaker 1: You have to exert effort to work against the force
Speaker 1: of gravity to push the boulder up the hill. A
Speaker 1: battery likewise is exerting effort in the form of this
Speaker 1: exothermic reaction. The external circuit, that is, the larger circuit
Speaker 1: that you connect to the battery, is following the natural
Speaker 1: energy field. It isn't working uphill. It's got a high
Speaker 1: potential terminal and a low potential terminal, and the current
Speaker 1: flows according to the direct and of high to low
Speaker 1: as Franklin described, The actual electrons are going in the
Speaker 1: opposite direction. As the charge moves through the circuit, it
Speaker 1: encounters energy transforming devices. These would be things like light bulbs,
Speaker 1: heating elements, pretty much, you know, anything that you would
Speaker 1: connect to a circuit. At those points, some of the
Speaker 1: electrical potential energy of the charge gets transformed into some
Speaker 1: other form of energy, light, heat, whatever. The loss of
Speaker 1: electrical potential in a circuit after passing through one of
Speaker 1: these elements is often called a voltage drop. Now going
Speaker 1: to the water analogy again, imagine that you have a
Speaker 1: pool of water. You have a ramp set up above
Speaker 1: that pool of water, like maybe it's like a water slide,
Speaker 1: and the water slide is not turned on, uh, and
Speaker 1: it's smacked aub in the middle of the pool. You're
Speaker 1: also in the middle of the pool, and you grab
Speaker 1: a bucket and you fill it up with water from
Speaker 1: the pool. You lift the bucket up over your head
Speaker 1: to the top of the slide, and you tip the
Speaker 1: bucket out so that the water hits the slide, goes
Speaker 1: down the slide off the other end back into the pool. Well,
Speaker 1: you've just taken water from an area of low potential
Speaker 1: energy in this case, kinetic energy, and you moved it
Speaker 1: using work to an area of high potential energy. The
Speaker 1: water then flows down the ramp till it gets the end.
Speaker 1: And maybe you even put a water wheel at the
Speaker 1: base of this slide, so when the water hits the
Speaker 1: water wheel, it actually provides the work necessary to turn
Speaker 1: the wheel and you get the wheel turning. You have
Speaker 1: this display of mechanical energy from the water. So that's
Speaker 1: kind of what you would see with a battery in
Speaker 1: a circuit. In this example, you are fulfilling the same
Speaker 1: purpose of a battery. You are lifting some water using
Speaker 1: work from an area of low potential to an area
Speaker 1: of high potential. The battery is doing this but with
Speaker 1: electrical potential, not with you know, physical stuff. Okay, now
Speaker 1: it's time to define an actual vault. I alluded to
Speaker 1: this in the first segment of this podcast. We've got voltage,
Speaker 1: which is this difference in electrical potential between two points.
Speaker 1: And we understand that creating a conductive path between an
Speaker 1: area of high electrical potential and one of low electrical
Speaker 1: potential allows for the flow of current. So how do
Speaker 1: we define a vault. Well, there's actually a couple of ways.
Speaker 1: One is to say that one volt is equivalent to
Speaker 1: the energy consumption of one jewel per electric charge of
Speaker 1: one coolomb. But that just raises more questions, doesn't it.
Speaker 1: The dictionary definition of a jewel is a unit of
Speaker 1: work or energy equal to the work done by a
Speaker 1: force of one Newton acting through a distance of one meter,
Speaker 1: and a Newton is a unit of force. One Newton
Speaker 1: is the force required to impart an acceleration of one
Speaker 1: meter per second per second to a mass of one
Speaker 1: kim okay, So a jewel is the energy required to
Speaker 1: produce a Newton's worth of force through a distance of
Speaker 1: one meter. What's a coulomb. A coulomb is a unit
Speaker 1: of electrical charge equal to the quantity of a current
Speaker 1: of one ampier in one second. It's named after Charles
Speaker 1: Augustine de Coulomb, who in the late seventeen hundreds developed
Speaker 1: a description of the force that interacts between electrical charges.
Speaker 1: He had determined that like charges repel each other and
Speaker 1: that opposite charges attract each other, and his work led
Speaker 1: to further discoveries that the force of this repulsion or
Speaker 1: attraction is proportional to the products of the electrical charges
Speaker 1: and inversely proportional to the square of the distance between
Speaker 1: those two charges. And this is what we now call
Speaker 1: Coulomb's law and another way to define volt That was
Speaker 1: one way, but here's the other one. It's equivalent to
Speaker 1: one amp of current times the resistance of one ohm.
Speaker 1: And oh my goodness, looks like we're gonna have yet
Speaker 1: another thing to talk about here. And while you might
Speaker 1: hear that resistance is useless, I'm here to tell you
Speaker 1: it's pretty important in the case of circuitry. So I
Speaker 1: talked about how copper is a good conductor because of
Speaker 1: those free electrons, right well, the single electrons in the
Speaker 1: outermost energy shell around a copper nucleus make copper a
Speaker 1: great conductor of electricity. We describe this quality of copper
Speaker 1: as conductance, or the ease with which electrical current may
Speaker 1: pass through that substance. The opposite quality is called electrical resistance,
Speaker 1: the opposition of a material to the flow of current
Speaker 1: through it, And typically we talk about that with materials
Speaker 1: that have fewer or no free electrons, making it more
Speaker 1: difficult for electricity to pass through. Even copper has some
Speaker 1: electrical resistance. It's not a perfect conductor, at least not
Speaker 1: under conditions you and I would typically experience. Resistance is
Speaker 1: kind of like the concept of friction, right. We know
Speaker 1: that an object in motion tends to stay in motion.
Speaker 1: So if you were to roll a ball across a
Speaker 1: perfectly level surface, and both the ball and that surface
Speaker 1: were made of some magical material that ignored friction, there's
Speaker 1: no friction in this system, then that ball would roll
Speaker 1: forever unless it ran into something. But friction means that
Speaker 1: some of the energy of that rolling ball in a
Speaker 1: normal setting where we're using you know, a real ball
Speaker 1: and a real level surface, friction means that some of
Speaker 1: that energy gets converted into heat, and that means that
Speaker 1: there's less energy for that ball to continue to roll,
Speaker 1: and eventually the ball will slow down and stop rolling.
Speaker 1: Electrical resistance is kind of similar to that typically we
Speaker 1: see energy and electrical circuits convert into other forms like heat,
Speaker 1: which dissipate into the environment at large. Now I mentioned
Speaker 1: that one volt is equal to one amp of current
Speaker 1: running through one ohm of resistance. Resistance then is the
Speaker 1: ratio of voltage across whatever material we're talking about, divided
Speaker 1: by the current going through that material. So resistance is
Speaker 1: voltage divided by current, and conductance is the current running
Speaker 1: through an object divided by the voltage across it, So
Speaker 1: it's the reciprocal of resistance. Now we measure resistance in
Speaker 1: oms and ohm is the amount of electrical resistance between
Speaker 1: two points on a conductor when there's a constant potential
Speaker 1: difference of one volt applied to those points, producing one
Speaker 1: current or one amp here of current. I should say
Speaker 1: electrical resistance depends on a lot of stuff. Depends upon
Speaker 1: the atoms of the material itself, So the resistance of
Speaker 1: a copper wire will be different than the resistance of
Speaker 1: say a gold wire that's of the same thickness or gauge.
Speaker 1: It also depends upon the thickness or gauge of a wire,
Speaker 1: so a thicker copper cable will have less resistance than
Speaker 1: a thin copper wire. And it depends upon stuff like temperature.
Speaker 1: If you were to super cool some conductors, like get
Speaker 1: it near absolute zero, they would then have them perform
Speaker 1: as super conductors, which is material that can conduct current
Speaker 1: with no conversion into other types of energy like heat.
Speaker 1: You get no loss. In other words, likewise, there are
Speaker 1: some materials that have tightly packed electrons that resist this
Speaker 1: flow of current. I mentioned those earlier. We would call
Speaker 1: these insulators. So materials that insulate don't allow for the
Speaker 1: conduct conductivity of electricity or they severely restricted. Alright, so
Speaker 1: quick rundown voltage is akin to pressure. It's the difference
Speaker 1: in electrical potential between two points. Amperage is a measurement
Speaker 1: of current and explains how much charge passes a given
Speaker 1: point in a circuit within a unit of time. Ohms
Speaker 1: are a measure of resistance, or how much material resists
Speaker 1: the flow of charge through it. Now to define a what,
Speaker 1: so a what is the amount of electrical work performed
Speaker 1: when one ampere of current flows across one volt of
Speaker 1: electrical potential difference? So what is a unit of power?
Speaker 1: And this is where I find another stumbling block for myself,
Speaker 1: because in language we often swap out words that have
Speaker 1: similar meanings in other contexts, but very specific meanings in physics,
Speaker 1: and it causes confusion for people like me. So words
Speaker 1: like work, energy, power, and force they get thrown around
Speaker 1: a lot, and it's easy to forget what they all
Speaker 1: mean within the context of physics, and they mean different things.
Speaker 1: A force is something that causes an object to change
Speaker 1: its velocity in some way. Velocity is a vector quantity
Speaker 1: that means it has both a magnitude and a direction.
Speaker 1: So in our example of rolling a ball on a
Speaker 1: flat surface, that ball would tend to stay in motion
Speaker 1: at a constant speed and remain on a straight path
Speaker 1: on its own unless some other force were to act
Speaker 1: upon that ball and either speed it up or slow
Speaker 1: it down, or make it change its direction, or some
Speaker 1: combination of these things. That would be an external force
Speaker 1: acting upon this system. You can think of energy as
Speaker 1: the capacity for doing work, and it comes in lots
Speaker 1: of different forms. A moving object has kinetic energy. For example,
Speaker 1: work is a type of energy, specifically the amount of
Speaker 1: energy used to apply some force on some object over
Speaker 1: some distance. Now, as I mentioned earlier, the jewel is
Speaker 1: a unit of energy defined as being equal to the
Speaker 1: work done by a force of one newton across one
Speaker 1: meter in the direction of action of that force. We
Speaker 1: would describe the energy needed to lift a kilogram and
Speaker 1: move it a meter in a specific direction as work.
Speaker 1: Power is a description of the amount of energy used
Speaker 1: per unit of time. So if you expend twelve jewels
Speaker 1: of energy to do some sort of work, Let's say
Speaker 1: it's to to move a wheelbarrow a few feet. Uh,
Speaker 1: let's say that's that's how much energy you spent total
Speaker 1: moving that wheelbarrow. This is a totally hypothetical example. So
Speaker 1: you spent twelve jewels moving it. If you expended that
Speaker 1: energy those twelve jewels over the course of three seconds,
Speaker 1: your average output of power would be for watts. As
Speaker 1: you take the twelve jewels that you took to actually
Speaker 1: do this thing and the three seconds the amount of
Speaker 1: time it took you to do it, and you divide
Speaker 1: the twelve by the three, that's where you get the
Speaker 1: four watts. When we come back, I'll talk a little
Speaker 1: bit more about volts, amps, watts and how to read
Speaker 1: your power bill. But first let's take another quick break.
Speaker 1: I mentioned that one what is the same as one
Speaker 1: jewel of energy expended in one second. So what does
Speaker 1: it mean if your power bill is broken down by
Speaker 1: kill a watt hours. Well, it's kind of simple, and
Speaker 1: that a kill a watt hour is what it sounds like.
Speaker 1: It's the equivalent to one kill a watt of power
Speaker 1: sustained over the course of an hour of time. Since
Speaker 1: and this is a unit of energy, right, Since since
Speaker 1: one what is equivalent to a jewel per second? A
Speaker 1: kill a lot hour is equal to three point six
Speaker 1: mega jewels. Wait, how did I get that number? Well,
Speaker 1: jewel per two. Right, there are sixty seconds in a
Speaker 1: minute and sixty minutes in an hour, so we multiply
Speaker 1: sixty by sixty to get us three thousand, six hundred
Speaker 1: that's how many seconds there are in an hour. Then
Speaker 1: we multiply that by one thousand because we have one
Speaker 1: thousand watts because it's at kill a lot, So one
Speaker 1: thousand watts times three thousand, six hundred seconds we get
Speaker 1: three point six million. And remember a what is equivalent
Speaker 1: to one jewel per second? That means a jewel is
Speaker 1: equal to what's times seconds, So one thousand watts per
Speaker 1: hour three pint six mega jewels are equal. We use
Speaker 1: kill a wat hours to describe the amount of energy
Speaker 1: used to do work. So let's say you've got an
Speaker 1: appliance at home that requires a kill a lot in
Speaker 1: order for it to do its work. So it's gonna
Speaker 1: have a kill a lot of work in order to
Speaker 1: do whatever it's doing. Let's say it's an air conditioner.
Speaker 1: You gotta kill a what air conditioner. If you run
Speaker 1: that appliance for one hour, it consumes one kilowatt hour
Speaker 1: worth of energy to do that work. If you have
Speaker 1: a ten what device plugged in, it would take that
Speaker 1: device one hundred hours for it to use one kilowatt
Speaker 1: hour of energy. Power companies usually sell electrical energy in
Speaker 1: kilowatt hours, and it gets more confusing than that. Some
Speaker 1: regions have varying prices on kilowatt hours. Sometimes that price
Speaker 1: depends upon the time of day or the rate of consumption.
Speaker 1: So we're just going to leave it at that. But
Speaker 1: that's why we're talking about kilowatt hours as units, and
Speaker 1: you're really thinking about this is the amount of energy
Speaker 1: that is representative of doing a killer what worth of
Speaker 1: work within an hour. I haven't talked about direct current
Speaker 1: and alternating current yet, so I guess I should do that.
Speaker 1: A bit direct current is what you would find in
Speaker 1: a circuit connected to a battery. The direction of current
Speaker 1: is always going to stay the same because the positive
Speaker 1: and negative terminals on the battery are fixed. They can't swamp.
Speaker 1: The positive terminal is always positive. The negative terminal is
Speaker 1: always a drag guy. He's just always saying bad things
Speaker 1: about everybody. Alternating current switches the terminals in a circuit,
Speaker 1: and thus the direction of current switches back and forth,
Speaker 1: and it does this in cycles per second. So in
Speaker 1: Europe the standard is fifty times per second fifty cycles.
Speaker 1: In the United States it's sixty cycles per second. The
Speaker 1: reason we use alternating current is largely because of how
Speaker 1: it's pretty easy to adjust voltages for the purposes of
Speaker 1: power distribution. This is where things like resistance and voltage
Speaker 1: and ambridge really become important. So let's say you've got
Speaker 1: a power plant and that power plant produces one million
Speaker 1: watts of power. But then you have to distribute that
Speaker 1: power to the people who need it and the places
Speaker 1: that need it. So how do you do that. Well,
Speaker 1: you could send one million amps at an electrical potential
Speaker 1: difference of one volt, because remember the watts are it's
Speaker 1: really volts times amps. So if you have a million amps,
Speaker 1: then your voltage has to be one or you could
Speaker 1: send one amp very low current across an electrical potential
Speaker 1: difference of a million volts. One amp would only need
Speaker 1: a very thin wire. It doesn't need much wire at
Speaker 1: all and would have very little energy loss due to heat.
Speaker 1: A million amps would need an incredibly thick cable to
Speaker 1: avoid losing too much energy to resistance or burning through
Speaker 1: the wire entirely. And it would be very tricky to
Speaker 1: come up with a method that works for both distributing
Speaker 1: electricity across vast distances and also making use of that
Speaker 1: electricity once it gets to the home. Like once you
Speaker 1: get to the home, you don't probably want a super
Speaker 1: high current in your home. It would burn out all
Speaker 1: of your electrical appliances and probably kill you. Uh. You
Speaker 1: also don't want super low current for like super super
Speaker 1: low current, and you don't you know your voltage. You
Speaker 1: don't need super high voltage for the home. So how
Speaker 1: do you solve that problem? Well, direct current has issues
Speaker 1: with that. Alternating current, however, allows for the use of transformers,
Speaker 1: which lets you step up or step down the voltage.
Speaker 1: Now I've talked about transformers in other episodes, so I'm
Speaker 1: not going to go through all of that right now,
Speaker 1: but they are how a power company can increase or
Speaker 1: decrease the voltage. They can increase the voltage for the
Speaker 1: purposes of transmission, where transmitting power at high voltage is
Speaker 1: more efficient less power loss. You can push it further
Speaker 1: distances and then step it down when it comes time
Speaker 1: to distribute that power to read and so you step
Speaker 1: it up for the purposes of transmission. It gets to
Speaker 1: say a neighborhood, it goes to a different transformer that
Speaker 1: steps the voltage back down a bit, and then that
Speaker 1: transformers sends the power over to the households, where there's
Speaker 1: another step down to get it down to the standard
Speaker 1: in that house. So in the United States, that standard
Speaker 1: is one volts, all right, So really it's to make
Speaker 1: it more confusing, a pair of wires that combined offer
Speaker 1: two hundred forty volts of power, but that's because of
Speaker 1: alternating current. Most homes have an electrical service that provides
Speaker 1: between a hundred to two hundred amps, though there are
Speaker 1: exceptions both on the low end and the high end.
Speaker 1: There's more I could go into with direct current versus
Speaker 1: alternating current, including obviously the current wars between Westinghouse and Edison.
Speaker 1: A lot of people say between Tesla and Edison, although
Speaker 1: I think that's not entirely fair, uh, And I can
Speaker 1: also talk about the equations used to describe direct current
Speaker 1: versus alternating current. They are a bit different. But I'm
Speaker 1: going to hold off on all of that for a
Speaker 1: future episode because otherwise this episode would run way too
Speaker 1: long for me to get into that. Something else I
Speaker 1: did want to cover, however, was the difference between voltage
Speaker 1: and amperage when it comes to safety risks. Now we've
Speaker 1: established that these two factors are different. Voltage and ambridge
Speaker 1: described different things. Voltage again, is that pressure and ambridge
Speaker 1: is the amount of charge passing through a given point
Speaker 1: in a given amount of time. But which is more dangerous?
Speaker 1: Which one do you need to be more aware of? Well,
Speaker 1: you've probably seen signs that say things like danger high
Speaker 1: voltage when there's a fire at the disco or a
Speaker 1: fire at the taco bell. Make sure you let me
Speaker 1: know if you actually get that reference. It might just
Speaker 1: be making a joke for my own sake at that point.
Speaker 1: But is voltage the really dangerous factor here. Well, it's
Speaker 1: a bit more complicated than that. Let's say you encounter
Speaker 1: a current running at high voltage but very low ambridge,
Speaker 1: so there's a lot of pressure in the line, but
Speaker 1: not much electrical charge being moved through per second. That
Speaker 1: would be less dangerous than a current a high current
Speaker 1: with a relatively low voltage, So a high ambridge low
Speaker 1: voltage would be more dangerous than a high voltage low ambridge,
Speaker 1: And it doesn't take much amperage to do some damage
Speaker 1: to us. When you get a zapp from an electrostatic charge,
Speaker 1: chances are the brief current would have measured in the
Speaker 1: one to ten milla amp range, So a mill hamp
Speaker 1: is one of an amp. Less than that you probably
Speaker 1: would even feel it, and one to ten you would
Speaker 1: feel the little snap of an electric spark, but you
Speaker 1: wouldn't have any muscular convulsion at that strength of ambridge.
Speaker 1: Electro Static charges are are very high voltage but very
Speaker 1: low ambridge. At about ten milli amps of current, you
Speaker 1: would experience muscular contractions. If you grabbed hold of a
Speaker 1: wire that had ten or more milla amps of current
Speaker 1: running through that wire, you'd probably find yourself unable to
Speaker 1: let go. As you got shocked, your muscles would clamp down.
Speaker 1: At about twenty milla amps of current, you'd find it
Speaker 1: difficult to breathe. If the current were around one hundred
Speaker 1: miller amps, it would probably be fatal as it would
Speaker 1: interfere with the operation of your heart. And it might
Speaker 1: seem counterintuitive, but above two hundred milli amps you could
Speaker 1: actually survive the experience. So between one and two hundred
Speaker 1: is the real danger spot. Your heart would go into
Speaker 1: uncoordinated contractions and you would experience was called ventricular fibrillation,
Speaker 1: and that in fact can be fatal. Above two hundred
Speaker 1: mill amps, your heart would actually seize up. It would
Speaker 1: affect to really act as if it had been clamped down,
Speaker 1: so it wouldn't go into ventricular fibrillation, it wouldn't have
Speaker 1: those uncontrolled contractions. It would just stop. And if someone
Speaker 1: were able to shut down the current going through you
Speaker 1: fast enough, you could probably be revived. After that, you
Speaker 1: could be given resuscitation and recover. You would probably have
Speaker 1: some nasty burn injuries to deal with, and you would
Speaker 1: probably also have some injuries and and damaged to your
Speaker 1: internal organs. I have more to say about that in
Speaker 1: an episode about the electric chair, where we did it
Speaker 1: to people on purpose and continue to in some cases.
Speaker 1: So that's the key there is that you really want
Speaker 1: to be aware of the amperage and voltage is still important.
Speaker 1: It's not like it's pleasant to get zapped by a
Speaker 1: low amperage high voltage electric current, but it's not as
Speaker 1: dangerous as the the amperage would be. And it's those
Speaker 1: tiny little changes an amperage that will get you. So
Speaker 1: be aware. Now I'll have to do more episodes to
Speaker 1: talk about stuff like diodes, triodes, capacitors, and other components
Speaker 1: in circuitry. I've covered them in previous episodes, but I
Speaker 1: feel like taking this approach and really breaking it down.
Speaker 1: Getting to the basics builds upon an understanding that we
Speaker 1: can then rest more complicated subjects upon. Right, you can
Speaker 1: start once you start understanding how these circuit pathways work
Speaker 1: and what they do, and the behavior of electrical charge
Speaker 1: and why that's important. Then you can build on that
Speaker 1: and include things like quantum effects and why it gets
Speaker 1: difficult when you start getting into concepts like logic gates
Speaker 1: and quantum tunneling. You can you can touch on those subjects.
Speaker 1: You can also understand what a logic gate is, and
Speaker 1: you can understand how to build circuits to do actual,
Speaker 1: you know, tasks like how you can create a circuit
Speaker 1: to do calculations. But it all depends upon this basic
Speaker 1: understanding of what is going on with these electrical charges.
Speaker 1: And I find that if we start there we can
Speaker 1: build a better understanding of everything else as we go along.
Speaker 1: But that's gonna be for a later episode. Our next
Speaker 1: one is going to be about using electricity to kill you.
Speaker 1: I didn't. I did one on how people try to
Speaker 1: use electricity to help you, and that continues to this
Speaker 1: day to varying degrees of success in scientific rigor. And
Speaker 1: then we're gonna talk about the other extreme in our
Speaker 1: next episode, a pleasant topic to say the least, and
Speaker 1: then after that we'll cover all sorts of stuff. I
Speaker 1: haven't decided what goes on after that one, but if
Speaker 1: you guys have suggestions for things I should cover in
Speaker 1: future episodes of tech Stuff, you can reach out via
Speaker 1: email The addresses tech Stuff at how stuff works dot com,
Speaker 1: or you can reach out via social media. It's tech
Speaker 1: Stuff hs W both on Facebook and on Twitter, and
Speaker 1: go on over to our website. That's tech stuff podcast
Speaker 1: dot com. You'll find a link to the archive of
Speaker 1: all of our past episodes. You also find a link
Speaker 1: to our online store, where every purchase you make goes
Speaker 1: to help the show and we greatly appreciate it, and
Speaker 1: I will talk to you again really soon. Text Stuff
Speaker 1: is a production of I Heart Radio's How Stuff Works.
Speaker 1: For more podcasts from I heart Radio, visit the I
Speaker 1: heart Radio app, Apple Podcasts, or wherever you listen to
Speaker 1: your favorite shows.