Speaker 1: Get in touch with technologies with tech Stuff from how
Speaker 1: stuff works dot com. Hello again, everyone in Welcome to
Speaker 1: tech Stuff. My name is Chris Poulette and I am
Speaker 1: an editor at how stuff works dot com. Sitting across
Speaker 1: from me, well as usual, but dancing this time, his
Speaker 1: senior writer, Jonathan Strickland. Hey, there, I just looked up
Speaker 1: and there he was doing that thing, getting my getting
Speaker 1: my energy up. Actually, one of the things that uh,
Speaker 1: you know, we start the episode off pretty traditionally. One
Speaker 1: of the things that we had as an early ritual
Speaker 1: as we recorded Tech Stuff was Jonathan and I would
Speaker 1: be sitting here in the virtual darkness and someone we
Speaker 1: had different engineers over the time, over the years now,
Speaker 1: but someone would come in and turn on the lights
Speaker 1: and good lighted begs. But we wanted to talk a
Speaker 1: little bit about light, specifically light bulbs to day. So
Speaker 1: what a brilliant idea of those were? You know, before lightbulbs,
Speaker 1: Before light bulbs, there was no way to indicate that
Speaker 1: you had an idea. Yeah, yeah, there's no there's no yeah,
Speaker 1: pre light bulb there was no ting before we get
Speaker 1: into how light bulbs work in their history and everything.
Speaker 1: I want to lay down a little physics for you.
Speaker 1: All right, go ahead and enlighten us. I see, So
Speaker 1: we are talking about light and what is light. Well,
Speaker 1: light is made up of these very tiny particle like
Speaker 1: packets called photons. They've got energy, they have momentum, but
Speaker 1: there's one thing they do not have charge accounts mass
Speaker 1: or I was going they have no mass, but not
Speaker 1: no moss. Photons are these packets of energy. They have
Speaker 1: momentum but not mass. And these particles, these these photons
Speaker 1: are emitted by atoms. Once you have excited an atom
Speaker 1: to the point where it's electron starts to move out
Speaker 1: of its normal orbit and goes into a further orbit
Speaker 1: from the atoms nucleus. And once once you remove the
Speaker 1: energy source from that atom, the electron will eventually return
Speaker 1: to its normal orbit around the nucleus. But it has
Speaker 1: to it has to get rid of that energy that
Speaker 1: you have pushed into it. Right, Energy is not created
Speaker 1: or destroyed, it's just transferred. So this electron, as it's
Speaker 1: coming back down to its normal orbital is going to
Speaker 1: shed off energy, and in this case the energy is
Speaker 1: in the form of photons. Now, photons are going to
Speaker 1: be emitted in the entire spectrum of light. Now humans
Speaker 1: we are capable of perceiving a narrow band of that
Speaker 1: spectrum called the visible spectrum because it's visible to us. Oh,
Speaker 1: I always wondered about that. This is where the whole
Speaker 1: ROYGBIV thing comes in, right. The different wavelengths of light
Speaker 1: dictate what the color is as we perceive it. Uh.
Speaker 1: The but the the light goes well beyond outside the
Speaker 1: the visible range. There's things like ultra violet and infrared,
Speaker 1: and then you get into electromagnetic radiation as you go
Speaker 1: further out. But and anyway, Uh, these photons can come
Speaker 1: into various forms, so you can have a infrared photon
Speaker 1: or ultra violet photons. So uh, if it's in the
Speaker 1: visible light spectrum, we're able to see it. Now that's
Speaker 1: important because that's the whole basis of creating a light bulb.
Speaker 1: As you want to create some sort of device that
Speaker 1: you can used to create photons so that you can
Speaker 1: illuminate an area. And before light bulbs, you didn't really
Speaker 1: have that option unless you set something on fire. Uh.
Speaker 1: And there's a limited number of things we can set
Speaker 1: on fire before we set ourselves on fire, or we
Speaker 1: run out of stuff that is flammable, So it was
Speaker 1: a good idea to try and develop something that could
Speaker 1: create light in another way. Now, uh, how do we
Speaker 1: know about how what is the principle upon which light
Speaker 1: bulbs work. Well, again, if you excite an atom and
Speaker 1: you push those electrons out, when the electrons come back in,
Speaker 1: they emit photons. If you give enough energy to an object,
Speaker 1: then you can emit enough uh photons for it to
Speaker 1: be within the depending upon the nature of that material,
Speaker 1: for it to be within the visible spectrum for it
Speaker 1: to be perceptible. Because even if it's in the visible spectrum,
Speaker 1: if the energy is not great enough, you won't be
Speaker 1: able to see it. And we're all emitting energy all
Speaker 1: the time, like humans are emitting infrared energy all the time,
Speaker 1: and if you had an infrared camera, you'd be able
Speaker 1: to see it even in perfectly dark room. You look
Speaker 1: at the infrared camera, look at a person, you would
Speaker 1: see light as interpreted by the sensor in that camera
Speaker 1: and converted to visible light for us to see. You
Speaker 1: would be able to see that person because they're emitting
Speaker 1: that infrared light. Well, we may even depending on what what,
Speaker 1: depending on the material, it may even be emitting visible light.
Speaker 1: But it might be emitting at levels so low as
Speaker 1: to be imperceptible to humans. So if you add more energy,
Speaker 1: you can boost that and actually see the visible light. Uh.
Speaker 1: And this can happen with things like solid materials. And
Speaker 1: there was a fellow named John William Draper who in
Speaker 1: eighty seven demonstrated that solid materials, almost all of them,
Speaker 1: will glow once they reach a temperature of seven kelvin.
Speaker 1: Kelvin's a scientific scale for temperatures. Kelvin is what we
Speaker 1: have when you get to zero kelvin. That says that
Speaker 1: as cold as you can get, it actually refers to
Speaker 1: molecular movement, and at zero kelvin, there is no molecular movement.
Speaker 1: So that's like the deepest depths of space where there's
Speaker 1: nothing absolutely absolutely uh So, if you wanted to convert
Speaker 1: that into degrees that we're more familiar with most of
Speaker 1: us anyway, it would be about five and twenty five
Speaker 1: degrees celsius or nine seventy seven degrees fahrenheit, And at
Speaker 1: that temperature solid materials will start to glow. We call
Speaker 1: it the Draper point. Now, in order to have a
Speaker 1: object glow at a uh at a at an intensity
Speaker 1: bright enough for it to illuminate, say a room, you
Speaker 1: will have to put in more energy than that, right,
Speaker 1: because this is talking about they start to glow, but
Speaker 1: that doesn't mean that they're glowing so brightly as to
Speaker 1: illuminate an entire room. That's where it starts. So but
Speaker 1: you know, you've you've probably seen this. If you've ever
Speaker 1: seen a blacksmith work, then you know the blacksmith might
Speaker 1: be heating up iron and when they take that out
Speaker 1: it's glowing red. Or a glass blower or lava. You know,
Speaker 1: there's lots of stuff that tends to lava. It's not
Speaker 1: all manmade, but there's lots of stuff out there that
Speaker 1: um that that demonstrates this. So that's the principle. But
Speaker 1: but the idea behind an electric light source actually predates
Speaker 1: Draper's discovery. Really yes, back in well the early eighteen hundreds.
Speaker 1: I've seen I've seen reports from eighteen o six all
Speaker 1: the way up to eighteen o nine. There's some discrepancies there.
Speaker 1: But an English chemist and inventor named Sir Humphrey Davy,
Speaker 1: named Humphrey Davy, he was designated a night So that's
Speaker 1: the sir. He connected a battery to a strip of charcoal,
Speaker 1: and he used the electricity to actually heat up the
Speaker 1: charcoal to the point where it started to glow, which
Speaker 1: created technically the first electric arc lamp. Uh. This was
Speaker 1: not a viable means of illumination as it was hard
Speaker 1: to do. It required a lot of energy. The battery
Speaker 1: drained really quickly, the carbon burned at such a or
Speaker 1: it got so hot as to be incredibly dangerous for uh, say,
Speaker 1: I don't know a typical house um. So it was
Speaker 1: not something that was going to immediately be adopted into
Speaker 1: every household, but it was proving a concept. Uh. Also,
Speaker 1: by the way, Sir Humphrey Davy did go on to
Speaker 1: invent many things, including the Davy lamp, which was not
Speaker 1: an electrical lamp. It was a gas lamp. There was
Speaker 1: a gas lamp that had a mesh screen that would
Speaker 1: surround the flame so that miners meaning people who mind
Speaker 1: the earth, not people who are underage miners, could take
Speaker 1: the lamps, although depending in England at that point in time,
Speaker 1: the two may have been the same. Aim. Hey, our
Speaker 1: history has not always been a nice one. But the
Speaker 1: miners could take a lamp down below the ground, and
Speaker 1: even if they encountered a pocket of gas. The mesh
Speaker 1: would actually, this fine mesh would prevent the gas and
Speaker 1: the flame from making friends and becoming a big boom.
Speaker 1: Very important for miners of both types. So the he
Speaker 1: did invent that, Again not electrical, but I thought it
Speaker 1: was an interesting aside. Moving ahead back in the eighty one,
Speaker 1: Frederick de Moulins, and I'm sure I have completely mispronounced
Speaker 1: his name, and I apologized profusely for that. Another Englishman,
Speaker 1: Yeah it could be. He patented a light bulb in
Speaker 1: eight forty one, and this one was comprised of a
Speaker 1: glass case and a burner or burners actually made of
Speaker 1: carbon and in expensive material you may know as platinum. Yeah,
Speaker 1: you thought that led light bulbs were expensive, so uh
Speaker 1: he he patented that design. Again not really practical for
Speaker 1: for every day or even industrial use. An American inventor
Speaker 1: named J. W. Starr received a patent for a light
Speaker 1: bulb that used a carbon burner. Um and then the
Speaker 1: next few decades were spent among inventors trying to find
Speaker 1: a way to perfect the discoveries these earlier inventors had found,
Speaker 1: so that you could create a light bulb that made sense,
Speaker 1: that that was efficient, that could light well, that was
Speaker 1: not going to be prohibitively expensive. And there are two
Speaker 1: names in particular that pop up all the time, one
Speaker 1: of them being probably the most famous uh connected to
Speaker 1: the light bulb, which is Thomas Edison. Yes, it's funny,
Speaker 1: as we were recording this, we are rapidly approaching the
Speaker 1: hundred thirty third anniversary of the first test of Edison's
Speaker 1: incandescent light bulb. Yeah. Now, it is important to note
Speaker 1: Edison was not the person who invented the light bulb.
Speaker 1: He was not even the person to invent the incandescent
Speaker 1: light bulb, but he was someone who perfected that design
Speaker 1: and made it viable as an actual product. Yeah. Now,
Speaker 1: it's it's important to note, um that these these early lightbulbs, uh,
Speaker 1: you know, not only were homes not really wired. Actually,
Speaker 1: the light bulb, I would argue, based on my research
Speaker 1: the over the past, you know, the past times that
Speaker 1: we've done tech stuff, we've talked about Edison and Tesla
Speaker 1: and the lightbulb actually was sort of the key to
Speaker 1: getting homes wired for electricity. Yeah, I mean you and
Speaker 1: it made sense because suddenly you had households that could
Speaker 1: be uh safely with air quotes around that lit after
Speaker 1: dark and extend the useful uh time human being could
Speaker 1: get stuff done, because otherwise, when night fell, we might
Speaker 1: as well just go to bed because it was gonna
Speaker 1: be pretty dark. Well, you know, we're early to bed
Speaker 1: and early to rise, as they say, early to bed,
Speaker 1: early to rise, because otherwise you're barking your ship on
Speaker 1: the coffee table. Well, yeah, that's that's true. Well, gas lamps,
Speaker 1: uh were very very popular. But they were I mean,
Speaker 1: in addition to being obviously inherently somewhat dangerous um and
Speaker 1: oil lamps, but they were um smoky, um. They were dirty,
Speaker 1: so you know, I'm sure they probably didn't smell all
Speaker 1: that great um. But the problem with these early light
Speaker 1: bulbs is that they weren't very practical. O. Hey, look
Speaker 1: I got yeah, well, so much for that one. Another one.
Speaker 1: There was another inventor, an Englishman. The Englishman named Sir
Speaker 1: Joseph Swan, who was working on light bulbs around the
Speaker 1: same time as Edison. And Swan's bulb used carbonized paper
Speaker 1: as the burner, which worked pretty well except that it
Speaker 1: didn't last terribly long. And in fact, this was a
Speaker 1: problem that a lot of lightbulb. Researchers were encountering that,
Speaker 1: including Edison. The first problem was, all right, well, we've
Speaker 1: we found uh that if you if you run enough
Speaker 1: electricity through some sort of object, you can heat it
Speaker 1: up enough so that it begins to glow. But if
Speaker 1: that item is exposed to oxygen, then it will burn.
Speaker 1: So even if you found a material that does not
Speaker 1: melt at a high temperature, it would burn, it would
Speaker 1: combust at a high enough temperature because it'd be you know,
Speaker 1: it would be adjacent to oxygen, which you know that
Speaker 1: that's part of the fuel you need, you know, in
Speaker 1: order to have a fire. UM. So the you had
Speaker 1: to close it off from oxygen, which is why they
Speaker 1: were these these vacuum tubes essentially is what they create,
Speaker 1: these vacuum containers. UM. But once they got through that,
Speaker 1: they had to find what's the right material to use. Actually,
Speaker 1: what Edison ended up using at first was bamboo. He
Speaker 1: took Japanese bamboo and carbonized it and created a filament.
Speaker 1: In this case, what a filament is is this really long, long, long,
Speaker 1: long strip of material that is then coiled so that
Speaker 1: you can decrease the space that it needs to um
Speaker 1: to fit into whatever you want to put it in,
Speaker 1: so it's got a lot of surface areas. Then the
Speaker 1: resistance is high. A resistance in electricity is the the
Speaker 1: materials resistance to electrons flowing through it freely. The more
Speaker 1: resistance there is in general, Okay, you've got greater resistance,
Speaker 1: you have greater heat. Well, the secret to the light
Speaker 1: here is the amount of heat that's being generated. That's
Speaker 1: the energy that is creating this whole system of electrons
Speaker 1: being pushed out and then when they start coming back in,
Speaker 1: the photons are being let out. So let let the
Speaker 1: photons out? Who let the photons out? That was as
Speaker 1: an a swan as it turns out. Um, it's interesting
Speaker 1: because then Edison Edison ended up hiring what his first
Speaker 1: his first light bulb design used a temperature controlled switch
Speaker 1: to try and keep the material at the right temperature
Speaker 1: so that it would the light bulb would remain lit longer.
Speaker 1: Because that was an early problem with these light bulbs
Speaker 1: is that their their utility was low because they couldn't
Speaker 1: you couldn't burn them for very long. But this was
Speaker 1: a problem because the the temperature control controlled switch, once
Speaker 1: a certain temperature was hit, it would switch off right,
Speaker 1: the light would go off, and so it started creating
Speaker 1: this flickering problem and made the bulb practically unusable. So
Speaker 1: he then hired a physicist from Princeton named Francis Upton,
Speaker 1: who led Edison's research team working on light bulbs, to
Speaker 1: start practicing with other stuff. That's when they came upon
Speaker 1: the idea of using the bamboo as a filament. Um.
Speaker 1: Swan and Edison ended up battling each other. Edison ended
Speaker 1: up taking patent lawsuits against Swan, but then ultimately the
Speaker 1: two of them formed a partnership together and they created
Speaker 1: the Edison Swan United Company. Teamwork, teamwork. Um. Yeah, just so,
Speaker 1: just so you guys know, patent wars are not a
Speaker 1: new thing. Oh no, not in the least. Um. Yeah,
Speaker 1: it's funny. While u while carbonized bamboo sounds like an
Speaker 1: ingredient for a hipster sandwich, Um, it did have the
Speaker 1: ability to burn for more than which you know, back
Speaker 1: in that time, that was pretty nice for a for
Speaker 1: a light bulb. Yeah, and uh, this served as the
Speaker 1: basis for what future light bulbs would be. And then
Speaker 1: we ended up shifting to a different type of filament.
Speaker 1: But we'll get into that in a second. So let's
Speaker 1: talk about the basic anatomy of an incandescent light bulb.
Speaker 1: And don't worry Floresce in an L. E. D. Fans,
Speaker 1: We're gonna get to you too. You just sit tight.
Speaker 1: So the incandescent bulb, You've got two contacts to two
Speaker 1: electrical context on this on a typical incandescent bulb. One
Speaker 1: of them is at the very end of the bulb,
Speaker 1: that's the base of the bulb, and the other is
Speaker 1: in the actual treads that you screw into your um
Speaker 1: light bulb socket. Yeah. Actually usually has a squeaky noise
Speaker 1: which has that perfect pitch to give me the heavy gbs.
Speaker 1: It's like the fingernails on the chalkboard type thing. It's
Speaker 1: like almost every single light bulb in my house makes
Speaker 1: that noise. And so it's a physically demanding task for
Speaker 1: me because well, I guess psychologically really more than physically,
Speaker 1: because because I I suffer trauma. One follows the other.
Speaker 1: How many how many Jonathans does it take to you
Speaker 1: screw in a light bulb? Yeah, well, after the first one,
Speaker 1: it takes a few others to common down. Yeah, I'm
Speaker 1: not afraid of the dark. I'm just afraid of changing
Speaker 1: light bulbs, so that's not really true. I just don't
Speaker 1: like doing it. But anyway, these mental contacts are what
Speaker 1: create the the circuit, right, so that the circuits complete.
Speaker 1: When these two contacts are are in contact with the
Speaker 1: rest of the electrical system. On um, the contacts are
Speaker 1: attached to some wires and those wires are attached to
Speaker 1: the filament. Now, in this case, the filament is no
Speaker 1: longer bamboo. For your typical incandescent bulb, it's usually tungsten.
Speaker 1: And the reason why it's tungsten is a couple of
Speaker 1: different reasons. One is that the melting temperature of tungsten
Speaker 1: is really high, so you can heat tungsten up quite
Speaker 1: a bit and not worry about it being um melting
Speaker 1: away that. That's obviously another issue with light bulbs. Right
Speaker 1: you heat up materials, some material is gonna melt, and
Speaker 1: it might melt before you hit that draper point, which
Speaker 1: would be bad because you wouldn't get any light out
Speaker 1: of it. You would just get a you know, a
Speaker 1: glass cylinder of hot molten sludge. Um Hot molten sludge
Speaker 1: would be a great name for a band. It is, uh.
Speaker 1: It is, however, very thin the filament is very thin.
Speaker 1: As anyone who has uh smacked a light bulb hard
Speaker 1: enough to break the filament but not hard enough to
Speaker 1: break the glass knows that's really annoyed. That's another really
Speaker 1: annoying thing about changing lightbulbs. Oh when did I yeah,
Speaker 1: just ruined a perfectly good bye bulbs. So, yeah, it's
Speaker 1: very thin. Again, that's to increase resistance. That's another thing,
Speaker 1: is that a a a copper wire, for example, the
Speaker 1: the greater the diameter of a copper wire, the lower
Speaker 1: the resistance. So if you have a very um thin
Speaker 1: copper wire, the resistance is greater. That means it's going
Speaker 1: to also generate more heat as a result. Well, this
Speaker 1: tungusten same thing. I mean, this same principle applies across
Speaker 1: all materials. U tungsten filament is very very very thin.
Speaker 1: It's actually coiled twice. The first coil is done to
Speaker 1: decrease it's you know, the length, and then after you've
Speaker 1: coiled it once, you coil it a second time around. Uh.
Speaker 1: These these support wires, and uh that helps when the
Speaker 1: tungsten heats up, it starts to generate, you know, give
Speaker 1: off these photons. Uh, it helps, Uh, concentrate that light
Speaker 1: so that you have enough for it to be useful,
Speaker 1: because again, you want to give enough energy there for
Speaker 1: you to have visible light that you can actually see
Speaker 1: stuff by, but you don't want to have to pour
Speaker 1: in more energy than was necessary. And we should point
Speaker 1: out incandescent bulbs not terribly efficient. No, we think about
Speaker 1: heat being a a wasted form of energy in this case,
Speaker 1: and how hot and incandescent bulb gets. And it's also
Speaker 1: giving out photons outside the range of visible light, so
Speaker 1: you're getting you know, infrared light and maybe even ultraviolet
Speaker 1: light from from these light bulbs. Well that that means
Speaker 1: that again it's a drop in efficiency. I mean, yeah,
Speaker 1: it's giving off light, but we can't see it, so
Speaker 1: it doesn't do us any good, not not in a
Speaker 1: normal application. Anyway. You know, if you're doing something that
Speaker 1: required infrared or ultraviolet light, than sure, although there are
Speaker 1: better ways of doing that than using a regular incandescent lightbulb. Yeah,
Speaker 1: I mean you you could. You could even cook brownies
Speaker 1: with it, which is with an easy bake oven. It's
Speaker 1: funny because I don't think people, not everyone realizes this.
Speaker 1: It's not like a secret. But um, the the older
Speaker 1: easy bake ovens, especially they're they're essentially using the heat
Speaker 1: from a lightbulb to cook uh, you know, very simple
Speaker 1: cakes and brownies and things like that. Right now, the
Speaker 1: you know, you might ask what's inside a lightbulb? Besides
Speaker 1: all this stuff, there's actually a gas that's inside most
Speaker 1: incandescent light bulbs, and it's usually are gone, which is
Speaker 1: an uh it's an inert gas, meaning it does not
Speaker 1: react to other stuff. Hey, are gone gas. It's a
Speaker 1: tornado outside. So like, oh, you never do anything now
Speaker 1: that you want it to be inert because obviously, like
Speaker 1: something like oxygen, then the tungsten would start to burn.
Speaker 1: It would dramatically decrease the life lifespan of your average
Speaker 1: light bulb. So they pump the oxygen, They pump air
Speaker 1: out of the glass globe and fill it with our
Speaker 1: gone gas. Yep. And so you might say, well, why
Speaker 1: why not just have a vacuum inst of our gone gas.
Speaker 1: The reason for that is that, uh, at that high temperature,
Speaker 1: you have another problem besides combustion, even if you don't
Speaker 1: have oxygen, the other problem is evaporation. Atoms from the
Speaker 1: tungsten will actually evaporate off the filament. Because of those
Speaker 1: high temperatures, and over time, that means that you're losing
Speaker 1: you know, every time you're using that light bulb, you're
Speaker 1: losing tungsten with the old light bulber. Yeah, and with
Speaker 1: the old light bulbs, you would actually have the tungsten
Speaker 1: start to evaporate away and coat the inside of the
Speaker 1: light bulbs, So the light bulb would get more and
Speaker 1: more dim both because there was less filament to light
Speaker 1: and because all the filament that was gone is now
Speaker 1: coating the inside of the light bulb making it darker.
Speaker 1: So uh, by using argon, what it actually acts as
Speaker 1: is sort of a sort of a barrier. These atoms
Speaker 1: from tungsten will come off the filament, bump into a
Speaker 1: an argon atom, and then because argon's a nerd, it's
Speaker 1: not going to act with that that um uh energy
Speaker 1: or that that particle. Rather, the particle then returns to
Speaker 1: the strip of tungsten um. So it acts as kind
Speaker 1: of a cushion. It's just pushing the the atoms back
Speaker 1: to the tungsten. Keeping that filament last to last longer
Speaker 1: very important. And so that's the basic premise behind these
Speaker 1: incandescent bulbs. The a uh, you know, they get to
Speaker 1: a pretty hot temperature. We're talking around degrees celsius or
Speaker 1: four thousand degrees fahrenheit um, because again you want to
Speaker 1: put out enough visible light for it to be useful.
Speaker 1: Now that all depends on the wattage of the bulb. Yeah,
Speaker 1: which generally speaking, you can think of his brightness. Um,
Speaker 1: it's it's kind of or or really you can think
Speaker 1: of his brightness or how hot that tungsten's getting inside
Speaker 1: the light bulb. That's what that kind of translates into.
Speaker 1: Uh and uh. Interesting. We have an article on the
Speaker 1: site how light Bulbs Work and how stuff Works dot com.
Speaker 1: Great article, great illustrations, a fun read. I mean, I
Speaker 1: really do mean that. It's actually you would think it's
Speaker 1: an article about light bulbs, but it really is a
Speaker 1: fun read. And one of my favorite uh facts in
Speaker 1: this is that a typical sixty what bulb has a
Speaker 1: tungsten filament that six and a half feet or two
Speaker 1: meters long and one hundred of an inch thick. I
Speaker 1: don't have the centimeters for that, sorry, but it's you know,
Speaker 1: six and a half feet long or two meters and
Speaker 1: if you were to completely uncoil that filament, however, once
Speaker 1: it's all double coiled. It's in a space that's shorter
Speaker 1: than you know, the tip of your pinkie finger, and
Speaker 1: you're thinking, wow, that's to go from six and a
Speaker 1: half feet to that is pretty impressive, you know. And
Speaker 1: again that's packing all that material in so it can
Speaker 1: give off enough light for it to be useful. Yeah,
Speaker 1: now do you uh, do you happen to know how
Speaker 1: three way light bulbs work? I do not. Actually, as
Speaker 1: a matter of fact, we have another very very short
Speaker 1: article on how three way light bulbs work and it
Speaker 1: they also have to filaments. Um, it's it's very interesting.
Speaker 1: Now the socket has to accommodate that because it has
Speaker 1: to do also with a connect on the outside. But
Speaker 1: essentially what happens is that the socket is, you know,
Speaker 1: through a switch, providing instructions on which of the two
Speaker 1: filaments to light. So for the first on switch, if
Speaker 1: you've ever used the three way light, you know that
Speaker 1: the first one is the lowest setting uses the least
Speaker 1: amount of electricity. Well, the one filament that is designed
Speaker 1: for that lower setting comes on when you click the switch. Again,
Speaker 1: that provides instructions for the second filament, but only the
Speaker 1: second filament to come on, and then the third the
Speaker 1: two team up. I see so, and then that the
Speaker 1: next is off. Got you. You get these the sum
Speaker 1: total of light coming from the bulb, which is if
Speaker 1: your pardon upon a brilliant weight. I do that because
Speaker 1: it's very simple, shiny. So moving on. That's a little
Speaker 1: just aside and firefly reference for you guys out there.
Speaker 1: And of course you can achieve different effects to with
Speaker 1: the kind of glass. You might be wondering, you know
Speaker 1: that the what the natural lighting or the what does
Speaker 1: the blue what's the blue one do? Well, it's just
Speaker 1: diffusing the uh photons given off by the tungusten inside
Speaker 1: the light bulb a little bit different. And I should
Speaker 1: point out an eat that depending upon the material you're using,
Speaker 1: that will determine what kind of light is given off. Right,
Speaker 1: So tungstens giving off this light uh, partially because of
Speaker 1: the fact that it's tungsten, But other materials give off
Speaker 1: different kinds of light, different colors of light along or
Speaker 1: or essentially lights that are different wavelengths, right, so different
Speaker 1: parts of the spectrum, sometimes visible, sometimes not. Uh. This
Speaker 1: is used in chemistry, it's used in astronomy, it's used
Speaker 1: in lots of different areas of physics, not just in
Speaker 1: creating light bulbs or you know, heating stuff up until
Speaker 1: it glows. But that kind of that's kind of the
Speaker 1: full discussion on incandescent bulbs. But those aren't the only
Speaker 1: kind of bulbs we have. We also have fluorescent bulbs. Yes, um,
Speaker 1: you might say, well, you know, uh, Edison and later
Speaker 1: the company that he was directly slash indirectly the founder
Speaker 1: of General Electric, you know, perfected the incandescent light bulb
Speaker 1: and uh uh you know, you would think that they
Speaker 1: would be very upset that the fluorescent came out. Well
Speaker 1: not really because, as we touched on on our famous
Speaker 1: or infamous GE series how how the famous that's more,
Speaker 1: that's the famous series on G E G E was
Speaker 1: actually in development of the fluorescent light bulb. Yeah, so
Speaker 1: fluorescent lightbulbs use a different method of generating lights, so
Speaker 1: you're not you don't have that physical filament inside a
Speaker 1: fluorescent bulb. Instead, what you have as a sealed glass tube.
Speaker 1: By the way, we also have how fluorescent lamps work
Speaker 1: at how stuff works dot com. So again you should
Speaker 1: read that if you're interested to learn all the physics
Speaker 1: involved in this. But in general, you've got a sealed
Speaker 1: glass tube and not the animal that Chris was alluding
Speaker 1: to earlier. It's just completely sealed. Uh. The tube has
Speaker 1: inside it's some mercury and there's also an inert gas
Speaker 1: like again are gone. Uh. The inside of this glass
Speaker 1: tube is coated with a powder that's phosphorus. Now, phosphorus
Speaker 1: means that when light strikes it, it gives off light.
Speaker 1: So that sounds like it could be totally useless, except
Speaker 1: we're talking about light within the entire spectrum. So even
Speaker 1: if if you have a certain kind of phosphor, it
Speaker 1: will um If you were to hit that phosphor with
Speaker 1: light that's outside the visible spectrum, for example, ultraviolet light,
Speaker 1: and then that phosphor actually emits visible light, that becomes
Speaker 1: useful because you can either look at stuff that is
Speaker 1: in the presence of light that's otherwise outside our our
Speaker 1: field of vision, or you can create something like of
Speaker 1: or escent light bulb that uses light outside of our
Speaker 1: vision to create light that's inside our vision. The way
Speaker 1: this works is you've got the electrodes at either end
Speaker 1: of this tube, uh that are wired to some sort
Speaker 1: of circuit. Now, the circuit once we turn that on
Speaker 1: starts to introduce uh, free flowing electrons into the gas. Now,
Speaker 1: this is different from the filament approach because then you
Speaker 1: have electrons running through a material directly right, just like
Speaker 1: you would a wire in a circuit. I mean, that's
Speaker 1: essentially what it is with this. It's free flowing electrons
Speaker 1: going through uh. The gas in this case are gone.
Speaker 1: It takes a little while for these electrons to be
Speaker 1: introduced into this this tube, which is why when you
Speaker 1: turn on most fluorescent light bulbs there's this little flickering
Speaker 1: moment while it's coming on. Yea because the cause again,
Speaker 1: the the has to introduce the the free flowing electrons
Speaker 1: for this to work. So once these electrons with considerable
Speaker 1: voltage are introduced, uh, the energy starts to change some
Speaker 1: of the mercury that's in that tube from liquid to gas. Now, again,
Speaker 1: when we're introducing electricity into or energy into an atom,
Speaker 1: it's exciting those electrons, pushing them out of their orbitals uh.
Speaker 1: And then when the electrons start to come back down
Speaker 1: to their normal orbital they'll give off photons. With the
Speaker 1: case of mercury, you're talking about light photons that are
Speaker 1: in the ultra violet wavelength range. So again you can
Speaker 1: you you're exciting the mercury and it's giving off ultraviolet light.
Speaker 1: We can't see ultra violet light unaided anyway, We're incapable
Speaker 1: of seeing light at that wavelength. But by coding the
Speaker 1: inside of that tube with phosphors that are able to
Speaker 1: absorb ultra violet light and then emit light in the
Speaker 1: visible spectrum, we can use that tra violet light two
Speaker 1: give us light we can see indirectly. We have this
Speaker 1: intermediary step with the phosphors, So the mercury starts to
Speaker 1: go from liquid to gas, gives off these ultra violet photons.
Speaker 1: The vultraviolet photons hit the phosphors, the phosphors absorbed the
Speaker 1: ultraviolet light and emit light in the visible spectrum, and
Speaker 1: voila or viola if you prefer, we have ourselves a
Speaker 1: fluorescent light bulb. By the way, if you have a
Speaker 1: black light, you essentially have a fluorescent bulb that does
Speaker 1: not have those phosphors necessarily on the inside because it's
Speaker 1: just emitting the ultra violet light directly. Uh And then
Speaker 1: you can have those wicked uh Van posters light up
Speaker 1: in pretty colors. All in all, You're just another brick
Speaker 1: in the wall, thank you. So, uh yeah, I mean
Speaker 1: that's the that's the essential way that fluorescence work. And
Speaker 1: this is also why because they contain mercury why they
Speaker 1: are so dangerous or potentially dangerous, because mercury is toxic.
Speaker 1: And if you were to, say, I don't know, drop
Speaker 1: a palette of fluorescent lightbulbs in a warehouse, you could
Speaker 1: have a potentially dangerous situation on your hands because you
Speaker 1: could very much have enough mercury there to suffer mercury poisoning. Yeah,
Speaker 1: it's some. It's in a way sort of amusing that
Speaker 1: so many of my friends remember busting fluorescent lightbulbs fondly
Speaker 1: because they make out. They make a loud noise. I
Speaker 1: had one. I was in a bookstore once when, uh
Speaker 1: and I was just perusing some books, so I'm very
Speaker 1: much focused on what I'm doing when the employee behind me,
Speaker 1: who was trying to change out a fluorescent bulb, accidentally
Speaker 1: dropped the one in her hands from a ladder and
Speaker 1: it landed directly behind me. And I thought I had
Speaker 1: just been hit by a shotgun. Okay, turned I wasn't
Speaker 1: well and and and at that time it wasn't uh
Speaker 1: popular knowledge. I probably shouldn't say common knowledge, but popular knowledge.
Speaker 1: People just didn't know, uh that there was mercury in there. Now,
Speaker 1: I mean, admittedly there's not a boatload of mercury in there,
Speaker 1: but you know, it could it could be something serious.
Speaker 1: And that's why when you're fluorescent light spurned out, it's
Speaker 1: a good idea to find someone who can take it
Speaker 1: and recycle that, not only for safety reasons, but also
Speaker 1: because you know they can recover some of that material. Now,
Speaker 1: when you're talking about the fluorescent light tubes, uh, that's
Speaker 1: pretty much it. I mean you've got the uh the
Speaker 1: tube of gas with the caps on the end, and
Speaker 1: you plug it into the uh the light fixture to
Speaker 1: have it work. Well, there's there's other stuff underneath that
Speaker 1: that you may not necessarily see. It's it's covered up
Speaker 1: by the fixture. UM. One of the most important parts
Speaker 1: I would argue is the ballast, which is a type
Speaker 1: of transformer uh um that basically ups the electricity to
Speaker 1: make it work better with the fluorescent light. Because again,
Speaker 1: you have to introduce those ions, which is not necessarily
Speaker 1: easy to do, especially since you've gotten inert gas in there.
Speaker 1: So if you ever looked at a compact fluorescent light
Speaker 1: or curly bulb as I like to call them, UM
Speaker 1: because I like to do that UM and wonder what
Speaker 1: the heck the big honking bases that you have to
Speaker 1: screw into a regular light fixture. That's where the ballast is.
Speaker 1: The ballast is built into the base of that uh
Speaker 1: that fixture, UM, which is why it may or may
Speaker 1: not fit into that incandescent and that that fixture that
Speaker 1: you bought that would allow you to use a UM
Speaker 1: a typical incandescent bulb. Now they say in some cases
Speaker 1: that you should not use those because they do generate
Speaker 1: heat and that can uh make the ballast overheat, uh
Speaker 1: cause a short circuit and possibly fire. You know at
Speaker 1: the ends on what kind of fixture you have, So
Speaker 1: keep an eye on that. But if you've wondered what
Speaker 1: that what that situation is, UM, it's built into the ballast.
Speaker 1: And the ballast is also in that case what controls
Speaker 1: the three way There are some three way fluorescent compact
Speaker 1: fluorescent lights. UM. The ballast is what makes that possible
Speaker 1: because it can control the amount of electricity going into
Speaker 1: the tube. Yeah. It's also important to point out that
Speaker 1: another big difference between using free electrons moving through a gas.
Speaker 1: Essentially you're talking about ionized gas or plasma. But I
Speaker 1: know if you're using free electrons moving through a gas,
Speaker 1: it does behave differently than it would if those electrons
Speaker 1: were moving through a wire. Uh. Now with a wire,
Speaker 1: you know you have the resistance is dependent upon the
Speaker 1: composition and the size of the wire in a in
Speaker 1: gas discharge, which is in the terms of this not
Speaker 1: something that's gross is uh uh, it's the resistance actually
Speaker 1: decreases due to current. So when you've got a current going,
Speaker 1: the resistance begins to decrease through this gas. That's more
Speaker 1: electrons and ions start to flow through. They bump into
Speaker 1: more atoms, frees up more electrons, creates more charged particles.
Speaker 1: So the resistance is uh is constantly decreasing as long
Speaker 1: as that currents on, and that can be a problem.
Speaker 1: If that continues for too long, it'll blow out the
Speaker 1: electrical components of the the the entire system. So that's
Speaker 1: another reason why these ballasts are important. They are little
Speaker 1: safety features that control that so that the current doesn't
Speaker 1: continue indefinitely. It stops briefly, but not so briefly as
Speaker 1: to make the lightbulb turn off, or at least if
Speaker 1: it's turning off, it's turning off at a rate so
Speaker 1: fast that we can't really detect it. Uh. You may
Speaker 1: have noticed, you know, lightbulbs that for us and bulbs
Speaker 1: that flicker like even when they're on, they're just they're
Speaker 1: just flickering. And that's generally speaking, that's the ballast that
Speaker 1: is trying to control this. And you're talking about alternating currents,
Speaker 1: the currents running essentially one way and then another way,
Speaker 1: so it's doing it, you know, and the ballast is
Speaker 1: working for both directions of current and UH, and some
Speaker 1: of the older bulbs, the system was not controlled very well,
Speaker 1: like they might have used a magnetic ballast, which has
Speaker 1: a slightly slower reaction time than current ballasts that are
Speaker 1: UH that are usually based on circuitry. So those older ballasts,
Speaker 1: you know, it meant that if you had a fluorescent
Speaker 1: bulb turned on, it might give you that flickering look
Speaker 1: and you might feel like your workplace is the same
Speaker 1: one that was in the documentary Joe Versus the Volcano.
Speaker 1: And that's right, you have a brain cloud. Well, then
Speaker 1: you have to go to this volcano. Uh, and encounter
Speaker 1: three different versions of the same triss And I was see,
Speaker 1: I was working on a joke about how when you
Speaker 1: were flying in your hot air balloon and you needed
Speaker 1: to go higher, you would throughout the fluorescent light fixtures
Speaker 1: because you know the kind of throw the ballast's overboard.
Speaker 1: Ironically enough, that's somewhat true. I've changed a ballast out
Speaker 1: of my fluorescent light fixture in my kitchen and they're heavy.
Speaker 1: They it's like a brick. Anyway, Well, we should probably
Speaker 1: move on to the third type of light bulb by
Speaker 1: wanting to talk about the LED. Actually, if you look
Speaker 1: at our article believe it or not, there's an article
Speaker 1: on how stuff works dot com about light emitting diodes. Yeah,
Speaker 1: we have articles on all of this, which made this
Speaker 1: podcast way easy to research. Yes, yes, But the funny
Speaker 1: thing is if you look at the diagram, the the
Speaker 1: cross section that are artists have put together of a
Speaker 1: light emitting diode, it's sort of in a way resembles
Speaker 1: an incandescent light bulb because it is a diode inside
Speaker 1: a casing. Yeah. Now, in this case, the the light
Speaker 1: of right, the light emitting die, it is a type
Speaker 1: of semiconductor. Actually, in a way, it's the simplest semiconductor.
Speaker 1: There is a diode in general, not just a light
Speaker 1: emitting diode, but a diode in general is a semiconductor,
Speaker 1: and it conducts electricity, but not as completely as it could. Right. Essentially,
Speaker 1: it's a semiconductor has a varying ability to conduct electricity,
Speaker 1: so sometimes it connect like an insulator, sometimes as a conductor.
Speaker 1: It all depends on this stuff. Generally speaking, if you
Speaker 1: control what what you have is, you've got a semiconductor
Speaker 1: with two different types of material and it tends we
Speaker 1: tend to call it N type material and P type material.
Speaker 1: So the N type material has extra negatively charged particles,
Speaker 1: so it has a negative charge overall. Then the P
Speaker 1: type material, I think you can see where this is going,
Speaker 1: has extra positively charged particles. Yes I'm positive, not just sure,
Speaker 1: I'm positive. So you can think of the N type
Speaker 1: material as having an excess of electrons. The P type
Speaker 1: material has what we call holes. These are places where
Speaker 1: the electrons could go. Now, electrons definitely want to get
Speaker 1: over to the positively charged holes. They want to move
Speaker 1: to those holes because, as we know, when you're talking
Speaker 1: about charges, opposites tracked John Marcia. Yes, in in subatomic
Speaker 1: particle form. So you've got the negative and the positive
Speaker 1: materials and they're kind of smushed together in a in
Speaker 1: a diode. So you've you bond together the N type
Speaker 1: material to the P type material. So you've got the
Speaker 1: the negatively charged and the positively charged botted together. And
Speaker 1: there's an electrode attached to each end. So the N
Speaker 1: type has an electrode attached, the P type has an
Speaker 1: electrode attached. Now, if you don't apply any voltage across
Speaker 1: this diode, the electrons from the N type material fill
Speaker 1: up the holes in the P type material, and it
Speaker 1: creates what is called a depletion zone. And in the
Speaker 1: depletion zone, the semiconductor becomes an insulator. You know, you've
Speaker 1: you've got those extra electrons, have filled up the holes
Speaker 1: that were on the positively charge side, and you've reached
Speaker 1: sort of a neutral ground, right, So depletion zone is
Speaker 1: that neutral ground. There are no free electrons or empty spaces,
Speaker 1: so it's just kind of there. But if you want
Speaker 1: to get rid of that depletion zone, then you need
Speaker 1: to push electrons across, moving from the N type area
Speaker 1: towards the P type area. And then to do that,
Speaker 1: you just connect the the IN type side of the
Speaker 1: diode to the negative end of a circuit P type
Speaker 1: side to the positive end, and the free electrons and
Speaker 1: the N type material are repelled by the negative side
Speaker 1: because again you know like charge repels like yes, they're
Speaker 1: drawn to the positive end, and you then complete the
Speaker 1: circuit and you get this um you get this electron movement.
Speaker 1: If you try to go the other way, it wouldn't
Speaker 1: work because the negatively charged particles going into the positive
Speaker 1: end would just fill up the holes and then it
Speaker 1: would stop. So a diode is kind of like a
Speaker 1: one way street and electronics. If you hook up a diode,
Speaker 1: uh current can only flow in one direction and it
Speaker 1: will not flow the other way. So if you even
Speaker 1: if you reversed the current, it would not complete the
Speaker 1: circuit if it went against the diode, Reversing the polarity
Speaker 1: just won't work, captain. So so that's your basic led.
Speaker 1: But visible light emitting diode are made up of materials
Speaker 1: that create a a wide gap between where the hole
Speaker 1: is and where the electrons are, so that when the
Speaker 1: electrons move through they do emit, They give off photons
Speaker 1: because again we're talking about when electrons are moving down
Speaker 1: through the orbitals. Uh, you know, you you've given them
Speaker 1: enough energy for them to to move out of their
Speaker 1: normal orbitals. Once they move down, they give off light. Well,
Speaker 1: the greater that gap is, the more light they give off.
Speaker 1: So if you create a visible light emitting diode and
Speaker 1: you use these materials that create these wider gaps between
Speaker 1: the conduction band and the lower orbitals of the electrons,
Speaker 1: that gap is what allows the electrons to give off light.
Speaker 1: And in general, these l e d s tend to
Speaker 1: look if you look at a single LED, they tend
Speaker 1: to look like a miniature light bulb light Christmas saying,
Speaker 1: now there's no filament in there, because again you're just
Speaker 1: what all you're doing is you're allowing those electrons to
Speaker 1: move in those those um orbitals and that's what's giving
Speaker 1: off the photons. And these little light bulbs tend to
Speaker 1: be shaped in such a way that it guides the
Speaker 1: light that's emitted in a very particular direction, so that
Speaker 1: way it's a very concentrated light. So if you see
Speaker 1: an LED light fixture, and this could be you know,
Speaker 1: an LED light bulb or on on the back of cars.
Speaker 1: I've seen a lot of um uh tail lights in
Speaker 1: recent cars that use L E D s And you
Speaker 1: can tell because it will be a group of them together. Um.
Speaker 1: And so it looks like there are lots of little
Speaker 1: tiny dots of light in a pattern you know, maybe
Speaker 1: a um a series of concentric circle type things, or
Speaker 1: or you know some other kind of thing um, and
Speaker 1: it's you can you can tell that it's an LED
Speaker 1: light specifically because you can see the little dots. But together,
Speaker 1: when they work together like that, they can be very bright.
Speaker 1: I have a couple of LED flashlights as a matter
Speaker 1: of fact, um that you know. You it's like, hey,
Speaker 1: does this thing work? Oh you know? Um. However, they're
Speaker 1: very efficient. Yes, yes, I've got a couple of LED
Speaker 1: lights in my house. Actually, there are a couple of
Speaker 1: light fixtures that were specifically designed to work with L
Speaker 1: A D lights and um, yes, they are incredibly efficient,
Speaker 1: particularly compared to incandescence and even fluorescence. But we didn't
Speaker 1: really mention, but florescent lights are more efficient than incandescent
Speaker 1: light bulbs, They last longer, they use less energy to
Speaker 1: create light. They don't they don't lose as much energy
Speaker 1: in producing heat. So yeah, so they don't heat up
Speaker 1: as hot as an incandescent bulb. That's not saying that
Speaker 1: a fluorescent bulb is going to be cool to the touch,
Speaker 1: it's just not going to be as hot as an
Speaker 1: incandescent bulb. Is l e ED is even more efficient. Uh,
Speaker 1: it has a much higher luminous efficacy, if you will.
Speaker 1: As we say in our article on l E D sage.
Speaker 1: I'm sorry, um, but they talked about how in our
Speaker 1: article they mentioned a specific type of LED light bulb.
Speaker 1: In this case, it was the Sewel's Evo lux LED bulb,
Speaker 1: which produces seventy six point nine lumens per what, which
Speaker 1: is essentially how bright This is dependent upon how much
Speaker 1: energy you're putting into it. Whereas an incandescent bulb is
Speaker 1: seventeen lumens per what, So seventy six point nine for seventeen.
Speaker 1: It shows that the efficiency of the l e ED
Speaker 1: is far greater than that of the incandescent bulb. And
Speaker 1: the LED lifetime can be around fifty thousand hours, So
Speaker 1: compare that to a couple of thousand hours for a
Speaker 1: typical incandescent bulb, and that's a big difference. Now, LED
Speaker 1: light bulbs do tend to be much more expensive than
Speaker 1: incandescent or fluorescent bulbs. However, if you measure that across
Speaker 1: the lifetime of the bulb and you factor in things
Speaker 1: like energy savings, uh, they on the long term can
Speaker 1: be a good investment. However, the upfront cost is still
Speaker 1: much higher, so that can be a barrier for a
Speaker 1: lot of people. The cost has been decreasing uh quite
Speaker 1: a bit since over the last decade or so, since
Speaker 1: semiconductor material has become much more cost effective. Is when
Speaker 1: these first came out, semiconductor material was a precious commodity.
Speaker 1: It was not something that was mass produced. It was
Speaker 1: not something that you could easily get your hands on,
Speaker 1: and so it was much more expensive. But just as
Speaker 1: Gordon More predicted way back in the sixties, the manufacturing
Speaker 1: processes would mean that costs would come down, efficiencies go up,
Speaker 1: and as a result, we're able to get more efficient products.
Speaker 1: Now he was talking specifically about integrated circuits, but as
Speaker 1: it turns out, that kind of applies to lots of stuff.
Speaker 1: Doesn't necessarily mean that the light bulbs will have next
Speaker 1: year will be twice as bright as the ones we
Speaker 1: have this year. So the analogy doesn't continue all the
Speaker 1: way there, but it's still I think semi applicable. Uh.
Speaker 1: So yeah, you can see the differences between these these approaches. Uh. Ultimately,
Speaker 1: it's all about again exciting atoms, and once those aboms
Speaker 1: get excited, they just light up, just like Chris does
Speaker 1: whenever I talk about Inner Space, his favorite movie. His
Speaker 1: face is lighting up right now. People, if you could
Speaker 1: call it that, Yeah, it's uh, it's funny. They're they're
Speaker 1: so excited and they just can't hide it. That's true.
Speaker 1: They're about to lose control. They think they like it,
Speaker 1: they think alright, So that wraps up I think this discussion.
Speaker 1: Unless you have anything else you want to add to
Speaker 1: light bulbs, Nope, all right, let's sign off. You guys
Speaker 1: can switch off the lights now. We're gonna wrap this up.
Speaker 1: You guys. If you have any topics you would like
Speaker 1: us to tackle in future episodes of tech Stuff, shoot
Speaker 1: us an email that addresses tech Stuff at Discovery dot com,
Speaker 1: or let us know on Facebook or Twitter. You can
Speaker 1: find us there with the handle text stuff hs W
Speaker 1: and Chris and I will thought you again really soon.
Speaker 1: For more on this and thousands of other topics. Is
Speaker 1: it how stuff works. Dot com