Video: Lewis Howard Latimer

﻿Hello scientists and welcome to this next lesson in your electricity topic. My name is Ms. Whittick, so far you've been learning about electricity with Ms. White, but I wanted to come along today and talk to you about a very interesting scientist called Lewis Howard Latimer. So in this lesson, you will need your exercise book or a piece of paper, a pen or a pencil and a calculator. If you haven't got that equipment, go and grab it now, pause the video and press play when you're ready to get started. Brilliant. Make sure you're sat somewhere nice and quiet, and that you've removed all distractions from around you, so you've closed down any extra tabs and you've turned off your notifications on your phone. In today's lesson we are going to talk about the story of Lewis Latimer firstly, and we're going to talk about how different types of light bulbs work. And then finally, we're going to compare the different types of light bulbs that are available. So Lewis Howard Latimer, this is him on the screen. He is a famous scientist, his father, that he was a slave who escaped to Boston and became the subject of a famous legal case. His owner tried to get him back, eventually, well, the Northern abolitionist paid off the owner and he was a free man. Lewis who's pictured here, fought in the Navy in the civil war and then he went to work for a patent office, which is a place where inventors can register their ideas so that they can sell them and nobody else can. This is where his enormous talent was discovered. He co-invented toilets for trains, and he also helped Alexander Graham Bell improve the design of the telephone. So there's lots of things that he was involved in. However, these are not his most famous contributions to science. So let's have a quick pause point and see what you can pick up from this. Have a read of the sentence on the slide and see if you can complete it. Pause the slide to do so. Brilliant, so Lewis Latimer helped invent toilets for trains. That's correct. Okay. So remember that next time you go to the loo on a train, Lewis Howard Latimer helped to invent those. Now he then went to work for Hiram Maxim, a company that was competing with Edison. You might have heard of Edison because he invented the first light bulb. So Lewis Howard Latimer, when he worked for this company, he invented something called the carbon filament bulb. Edison, who is credited for inventing the light bulb actually invented a paper filament light bulb. It was good, but it didn't last as long as the carbon filament. So Lewis Howard Latimer improved the design. He designed the carbon filament. He was sent to London amongst them other places to set up a factory for Maxim and was involved in putting electric lights onto the London streets. So before the carbon filament bulb was invented, the London street lights were gas lamps or oil lamps that had to be lit every night. So in actual fact, Lewis Howard Latimer ended up working for Edison, who was the man that invented the first light bulb, the paper filament one. And he stayed in Edison's company for the rest of his career. Also his son in law was the first black public school teacher in New York. So a quick question for you, let's do a couple and I'll give you a few seconds to think about the answers and I just want you to call them out, you don't need to write them down. So first question, what did Lewis Howard Latimer invent? Call out, three, two, one. If you said the carbon filament, brilliant, well done. So now let's write something down. I want you to complete the sentence, so copy it down and complete, pause the slide to do so. Have you written that down? Okay, let's see if you've got the right answer. Use the answer on the screen to mark what you have written down. Add any improvements you need to. Pause the slide now to do so. Brilliant, okay. Let's move on then. So we're going to talk briefly about how light bulbs actually work. So let's have a look then. This should be a familiar image. This is a filament light bulb. You may have some of these around your home. And this light bulb works in a very specific way. But, before that light bulb was invented, lighting at night in houses was either provided by candles or by gas powered lamps or sometimes oil palette lamps as well. They were quite dim these lights, they didn't provide a huge amounts of light and they also gave off carbon dioxide. Now that meant that they would, wherever way quite quickly, Latimer invented the carbon filament. And this was a fantastic advancement because of the incredible increase in light output of this bulb, so it produced a lot more light than a candle light would. Essentially, in this light bulb here that you can see, there is a very thin filament of hard to melt material, in this case, in Lewis Howard Latimer's case, carbon. Carbon conducts electricity remember because it's got free electrons. Excuse me. So a carbon is passed across the filament or through the filament, and that causes it to heat up. And as it heats up, it reaches temperatures well over 1000 degrees C. Now that's hot enough to make that material start to glow and that glow or incandescence, we sometimes call it, is the light that's being emitted from the bulb. We then use that light being given off to light up streets or room or whatever it might be that has the light there. So this meant when we had the bulb rather than candles or gas or oil powered lamps, that we could continue to work into the nighttime. Before it was very difficult because the light didn't give off a huge amount of light, so it was quite difficult to see by candle light. But Borgs men work continue through the night. People could safely move about the streets after dark. The filament, if it's left in the air, because it becomes incredibly hot, it would then react with the gases in the air. So the filament would start to react with the oxygen in the air, oxygen makes up about 20% of our atmosphere. And over time, this oxygen, if it's reacting with a carbon filament, will produced carbon dioxide. And that means that the carbon filament would start to disintegrate. So it would wear away over time. So what the next step was, to increase the lifetime of this filament, Latimer encased the filament in a glass bulb. And that meant that he could pump unreactive gases into there or inert gases inside that bulb. And so the filament lasted a lot longer, it wasn't exposed to as much oxygen. There was still a little bit of oxygen in there because there was still a little bit of air, however, it's a lower level, so it prolonged the life by a long time. The filament could still glow, but it wouldn't burn out as quickly. Now in modern light bulbs, the incandescent bulbs, carbon filaments are no longer used. So technology has advanced even further. We started off with the paper filament, went to the carbon filament, we now use an incredibly thin piece of tungsten. Now you can see here in this bulb, this filament here in the middle is a piece of wire that's been coiled many many many times, and it's really thin, and it's a piece of tungsten. Now tungsten has a melting point of over 3000 degrees, that was yes. And when the electricity passes through it, the particles heat up and the temperature increases and the tungsten glows, just like the carbon did. So let's have a look at a quick question, say the answers out loud for me. and I'll give you some thinking time as well. So first question for you. What is the wire that glows called? Three, two, one. That's right, it's called the filament. Well done if you said that. Next question for you, what is it made of in a modern bulb? So what's the filament made of in a modern bulb? Three, two, one, what's the answer? That's right, it's made of a very thin piece of tungsten. Next question for you. What word means unreactive? So what word did I use to say that the gases were unreactive? Three, two, one, what's the answer? If you said inert, that's brilliant, well done. So in your home, you might be aware that you don't really use filament bulbs as much. Bulbs have developed quite a lot, and there are new bulbs around. You might know that there's energy saving bulbs, those are the ones that take a little while to actually heat up and get as bright as they could be. But now we've got LED bulb. So let's have a look at this. Why do we use this? Now one of the biggest problems with the incandescent bulb that Latimer developed, was that they had to be incredibly hot to be working cause they have to glow really brightly. Now, you'll know that if you've ever tried to change a light bulb, a filament light bulb just after it's sort of broken and you haven't left it for long enough to cool down, the bulb is very, very hot. You mustn't touch them. Now that also means a lot of that energy that's being used to generate the light that is being released from the bulb is also wasted as heat energy from that bulb. So most of the energy from the electrical energy, wasn't actually going into lighting up the room, but actually into heating it in a very small way. Now I'm sure that you know, if you're cold in your room, you wouldn't turn on your light to heat up the room. That's not a reliable use of a bulb for heating. It's only a very small amount of heat that's produced from that, but still is wasted energy. So when energy resources were plentiful and we had loads of energy resources, demand was quite low for these energy resources. This wasn't a major concern that these weren't that efficient, but as time has progressed, we now are aware that energy resources are starting to run out, okay, our energy resources are fossil fuels, they're finite resources. That means we're using them a faster rate than they can be replenished. And so what we need to do is improve technology to mean that we're wasting less energy. And so the LED light bulb is one such development that's been made. So LED stands for Light Emitting Diode. Now a diode is an electrical component and that allows current to flow just one way through it and only under specific conditions. The emitting means to be given out so LED means that diodes give out lights, the l, light, e, emitting, d, diode. It's a diode that gives out light. Note, the incandescent bulbs are incredibly cheap to manufacture. They've been produced on a mass scale for a long time and the technology is all there to produce them. So it took quite a long time for people to start switching to newer technologies because the old ones are cheaper. Modern LEDs require much less energy to produce the same brightness of light. So in terms of electricity bills, they are cheaper to run, but they cost a lot more than the incandescent bulb because it's newer technology, they cost more to manufacture. So the upfront cost is higher to buy the bulb, but the running cost is much lower. And also LED bulbs have an incredible lifetime. So if you're weighing up those different factors, it's actually cheaper in the long run to use an LED bulb. Although the upfront cost it's higher. Many countries around the world have decided to stop allowing incandescent bulbs to be manufactured and sold due to that high inefficiencies, and their increased impact on carbon emissions around the globe. So a couple of key points for you, have a read. So I'll just give you a second to read those summary points through, and then we're going to do some quick fire quiz questions. Okay. What I want you to do when the next screen comes up is I want you to point to the correct answer. You don't need to write anything down. So first question for you, which bulb is more efficient? Point to the correct answer. Three, two, one, that's right, is the LED bulb, well done if you said that. Next question, which bulb costs less? Three, two, one, it's the filament bulb. Well done, if you said that. Next question, which bulb wastes less energy by heating? Three, two, one. It's the LED bulb. Next question. Which bulb lasts longer? Three, two, one, it's the LED bulb. Great job if you got those right. What I'd like you to do now is to have a go at this independent task. We going to write down some information. First, I want you to read the question through. If you think you know what you're doing, and you're confident to get started, feel free to pause the lesson now and answer this question. If you want a bit more support than hang on a second and I'll give you some key questions that you can answer here. So pause now if you want to get started. Here is some support questions. If you've already done your answer, then have a check and make sure you've covered these. And if you haven't, you can use these to structure your answer. So there's three questions on the slide there. Use those, pause the slide now and answer these questions. Okay, great job. Let's see what the answer is. So, you could have talked about any of these two advantages, or you could have talked about this disadvantage. We going to do a quick recap quiz on what we've learned so far. So again, I want you to point to the correct answer, there are four options each. What did Lewis Howard Latimer discover? Have a read of the options and point to the one you think is correct? Three, two, one, it's the carbon filament bulb, well done if you said that. Next question. Why was the carbon filament better than Addison's paper filament? Three, two, one, it lasted longer, well done if you said that. Next question. What does inert mean? Three, two, one, it means unreactive, well done. Next question. There are two options here, so give two advantages of an LED bulb. Three, two, one, hopefully you said it lasts longer and it's more efficient. What we're going to do now is compare the light bulbs. So I'm going to show you a table. I just want you to take a minute to have a look at this table. Pause the slide and see what it shows you. Okay, great. So we've got the two different types of bulbs here, carbon filament bulbs and LED bulbs. And we've been given some numerical values for their power, efficiency, lifetime and their price. Now, there are four questions that we're going to answer and that's for each column of this table, each piece of information we've been given. We're going to do this in the I do, We do, You do form. So I'm going to show you the first one. We'll do the second comparison together, and then I'll leave you to try the last two on your own. Now, these bulbs, as worth mentioning, are both the same brightness. They both give out the same brightness. So that's not a comparison that we need to be making between them. Let's have a look then. So you're looking first off at the power. Now, when we compare data, we cannot just read off the table. We can't just repeat what it said in the question without doing anything extra, that's not a comparison. So I'm going to show you a poor answer first, however, you through this. Why is this a poor answer? All I've done is repeated exactly what it said in the table. Just picked out those two numbers and listed them. When we compare data, we must do some kind of number processing, some calculations. So let's have a look at a good answer. Have a read through this one. Why is this answer better? Well, we've compared the numbers by doing the calculation. We've said the carbon filament bulb has a power input, which is three times larger than the LED bulb. We don't want it to have a large power input. Hey, we want the smaller power input for the same brightness. So, all that we've done here to work this out is we've done 15, the power input for the carbon bulb divided by five, the power inputs for the LED bulb. 15 divided by five gives us three. So we've said the carbon filament bulb has a three times higher power input or we could have said the LED bulb is a third of the power input, so the other way round. Let's have a look at the next comparison together. So we going to look at price together, have a look at this here. What are we not going to do? We're not going to just say the LED bulb costs £8 whereas the carbon filament bulb costs £2, why not? Because we're just repeating what it says on the slide. We need to make sure we do some kind of number processing. So let's divide the numbers. It doesn't matter which way round you do it because you can compare it either way. So divide the price of the carbon bulb by the LED bulb first. Pause the slide to have a go. Okay. Two divided by eight, you should have got 0.25. What do we know? That is in a fraction. It's a quarter, great. So, you could say that the carbon filament bulb is a quarter of the price of the LED bulb. What about the other way round, do two divide, oh, sorry, Eight divided by two now. Okay, eight divided by two gives you four. So we could say the LED bulb is four times more expensive than the carbon filament bulb. Let's just have a look at those steps. So, that's the first part that we talked about, but you could also say the LED bulb is four times more expensive, don't forget that you could do that that way. Brilliant. What I want you to do now then is I want you to compare the efficiency and the lifetime. Don't forget, you need to do some form of calculation here. If you can see what you're doing, then pause the slide now and have a go. If you can't, then I'll give you a little bit of a scaffold. Okay, here comes a little bit of help for you. Okay, we've got a sentence there to help you. I'm for the second one. And finally, you need to give a conclusion which bulb is best and give a reason. So pause the slide now to complete this activity. Let's go through the answers then. So, you could have said the LED bulb is three times more efficient than the carbon filament bulb or the other way around remember. So, I'm a third of the efficiency. The LED bulb lost nine times longer than the carbon filament bulb or the carbon filament bulb is a ninth of the lifetime. And finally, you need to say a comparison statement. The LED bulb is best because it lasts longer, it's more efficient and it has a lower power input, you could put in there despite having a higher cost to start with. You don't need to include all the reasons, you can just pick one, that's fine, but it's a good idea to link a couple if you can. Pause the slide now and mark your answer. Okay, great job. So just a quick summary for you of this lesson. Lewis Howard Latimer invented the carbon filament bulb. This was better than Addison's paper filament bulb, because it lasts longer. Modern bulbs like LED bulbs are more efficient and they last even longer. And when we write a comparison of our data, we must always do some kind of calculation in there. Great job in today's lesson. All that's left for you to do is to try the exit quiz. Thanks for taking part and have a great rest of your day. Goodbye.

Worksheet: Lewis Howard Latimer

Exit Quiz: Lewis Howard Latimer

Completed: Lewis Howard Latimer

This lesson looks at the work of Lewis Howard Latimer and his invention of the carbon filament light bulb. We will also compare different light bulbs and write analytically

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Lewis Howard Latimer

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