 Hi, I'm Zor. Welcome to Unizor Education. Today, the lecture will be very, well, non-theoretical. I'll just talk about certain devices which are used to generate electricity. So, no mathematics, almost, except in the very beginning I'll just recall one particular formula. Well, anyway, this is a continuation of the chapter of this course called electromagnetism. Well, the course is called Physics 14, it's presented on Unizor.com. I suggest you to watch basically the whole course from the website, not just one individual lecture, which you might be interested in. And now, this course has a prerequisite, mass routines on the same website. And, well, this lecture is an exception, there is no mass or almost no mass here. But most of the other lectures, which are related to physics, any kind of physical aspects, they do have mass. So, you really have to be proficient in your calculus, your vector algebra and something else. Okay, so, we were talking before about theoretical aspects of electromagnetism. Well, electricity in particular, it's kind of a more, it's a heavier part of electromagnetism, because we're using electricity everywhere in our houses, in our industry, etc. So, today I will talk about a very practical aspect. How do we obtain electricity? How do we generate electricity? Okay, there are certain different ways. Electricity is energy. And to have an energy, we have to take some other energy and convert it. Now, in this particular lecture, I will talk about kinetic energy converted into electric energy, into electricity. The next lectures will be dedicated to some, using some kind of chemical energy or some light energy, etc. But this is about kinetic energy converted into electricity. So, the most important, well, theoretical aspects of converging certain other energies, well, kinetic energy in this particular case, into electricity is, well, the magnetic induction. Well, we all know the formula that electromotive force can be generated in, well, let's say, if you have some kind of a frame and if you have magnetic field, variable magnetic field, in such a way that magnetic flux which is going through this frame is changing, then the changing of magnetic flux, actually the rate of changing of magnetic flux, is basically equal to generated electromotive force in this wire frame. And this is the principle in which all electric generators are built. So, we have to somehow generate variable magnetic field, so magnetic flux will change. The way how we usually achieve it in generators, and we were actually discussing this before, we either rotate the wire frame in the magnetic field or we keep the wire frame stationary and we rotate the magnetic field by rotating basically magnet inside the wire frame. Now, obviously, it's not just one wire frame that many, many different loops and that's how basically electric generator is organized. So, we have to have a rotation. So, that's what's the most important part when we are generating electricity from kinetic energy. Our kinetic energy must be somehow converted into rotation because it's the easier and that's most practical way of generating electricity from the kinetic energy. So, what kind of rotation we have, which we can use to generate electricity? Well, to rotate the rotor inside the electric generator, which will generate electricity. This lecture is about rotation, basically. How can we get rotation? Now, there are certain very simple devices which go back to the time immemorial, which can be used to achieve rotation using something which we already have in our possession in nature. Well, we have the flow of water flowing in a river. Well, that was the first source of energy which people could use to generate a rotation. Well, they were doing something like pumping the water from one place to another using mills, for instance. So, that's one of the things. So, a contemporary way of using the flow of water or the flow of wind, because they are similar in the way how we use these, is a propeller. So, everybody knows what propeller actually is, right? So, it has, this is the axis and it has certain, I don't know, wings or whatever else, which are turned at certain angle. So, if you have the flow of water or flow of wind, as soon as they hit the surface of one particular wing of this propeller, since the wing is at the angle, so what happens is this is the flow of wind or water and this is the way how my plane actually, which goes against this, is positioned at a certain angle. Well, since there is an angle, there will be, well, if you will actually represent the force as a combination of different force because you have a surface, if you have a surface of this wing, then the force goes this way, right? So, it has two different components, the vertical component and the horizontal component. The vertical component actually is a pressure on the axis, on this axis, and the horizontal component will be rotating the propeller. So, this is a very simple thing. The propellers were used, as I'm saying, from the time immemorial and this is the way how we generate rotation from the flow of water or the wind. So, that's in case we already have the water and the wind. Well, it's not always like that and energies need it everywhere. It's not like in every place we have some kind of water which we can use and don't forget that to have this particular thing generated a substantial amount of power, you really have to do something. Well, the Hoover Dam, if you know, is basically cutting off the water flow and it has a dam and the water actually raises. So, now this is the level of water, this is our dam, this is the Hoover Dam and then, as soon as it reaches certain height, then it flows from here down. As it goes down, it's much more pressure than if you're just using the flow of water. Now, this is the falling water. That's where Niagara Falls, for instance, is. The falling water has significantly more kinetic energy by using gravitation, the gravity of the earth. So, the falling water has more kinetic energy than just flowing along the river. And now here we can have this propeller and it's circulating because the flowing water going on the wings of the propeller will turn it around and that's where we get this rotation. With wind also, I mean, yes, it's good if there is a good wind, but it might be or might not be. So, natural, and by the way, this type of hydroelectric station, hydroelectric power plants, well, it has its own drawbacks as well because since we are actually have to do something like put the dam and the river goes up, which means it floods a lot of area around it and it might or might not be a good thing for the nature. We're trying not to disturb the nature as much as possible. This type of hydroelectric station is very intrusive to nature. Well, the wind, the power plants which are built on the wind flow also are kind of intrusive. Well, first of all, they take a lot of space because they are big actually and there are many, many different propellers installed relatively high in the air and there are birds actually which are getting hurt, etc. So, there are negative things and it's not always flowing. The wind is not always flowing. So, okay, so we need something a little bit more, I would say, reliable, but again, there is no ideal thing for every kind of device which we are using to generate electricity. Well, it is intrusive in some way or another against the nature, but we are basically doing whatever we can to try to be good to nature, but at the same time, you know. So, the next thing is, well, we can produce artificial flow of something. That's where the thermal power point go. Now, the thermal power point usually generates steam from water using some kind of a heating mechanism. Now, as soon as you generate the steam from the water, well, the more steam you generate, you can have more power basically, it's very simple. Okay, so what usually is used for the source of the heat is, well, it used to be coal and oil, the natural gas. These are burning basically and they're converting water into a steam and the steam is directed towards the same propeller which we were talking about. In this case, it's not just a propeller, it's called a turbine. Now, a turbine is actually, you have coaxial propellers of different kinds. So, the flow of steam goes this way and it rotates all these propellers, coaxial propellers. Now, why do we need many of them? Well, because as soon as the steam hits one of those things, it basically reflected and it has certain other energy in the reflected flow of steam and it can be used as well. That's why we have different shapes of different propellers so that somehow they're trying to use as much energy, extract as much energy from the flow of steam as possible. And on the website, in the notes for this lecture and every lecture has a notes, I have a couple of pictures. One of them is a picture of a propeller and another is a picture of a turbine which basically contains a lot of different propellers installed on the same axis. So, what other energy source to generate the steam? So, basically, what other heat energy which we can use? I mentioned oil, coal, natural gas, obviously nuclear station. It sounds very scientifically like nuclear station. Well, it does have something to do with nuclear physics. However, the final product of nuclear power station is just heat and it's just heating the water to produce steam and the steam goes against the propellers and against the turbine to basically generate electricity. So, what else? Yes, there is a source like volcano for instance. Volcano is a geothermal source and there are some electric power stations which generate this energy which is inside our planet. Quite frankly, I don't know how it's done. I mean, obviously, it's not against some real volcano, but there is a heat which is generated in any, even the old volcano and that heat somehow might be used to generate the steam, to produce the steam from water. That's basically it about having these rotational movements generated from either natural or artificial flow of some substance at the propeller. So, it's all based on using the propellers in different kind of devices, usually called turbines. Now, in the car engine, we have a different way of generating rotational movement. The car engine is, I'm talking about internal combustion, not about electrical. Electrical cars, they have batteries and they generate basically directly the rotational movement which is a very, very simple thing. The electric cars are extremely simple in their construction. The problem is the batteries, but that's besides the point. We are not talking about this right now. We'll talk about when we'll use the chemical energy as a source of rotation or the source of electricity. But in this case, we're talking about mechanical usage and in the car we have internal combustion engine. So, what is internal combustion engine? Well, basically it's a very simple thing. You have some kind of a camera and you have a piston. So, there is a tool and an air or whatever coming into this spark and then it moves the piston up. So, that's it. Then something, we move it down again and then again we pump in some kind of a gases thing which can be, again, spartal and it will move it up and down. So, basically that's what we have. This is the up and down movement of the piston in the car engine. It's called reciprocal movement. It goes up and down, up and down. And somehow we have to use this up and down movement to create rotation. And this is done using, again, a relatively simple mechanical device. So, the way how it's done is the following. This is my piston which goes up and down. Now, this is called connecting bar and then here we have something which is called crankshaft. So, the crankshaft is something like this. Now, it's not really a hard connection. There is a rotation mechanism here. So, whenever, and this thing also is rotating. So, as this thing is moving up and down, this thing is rotating. And since this is not a hard connection but basically a flexible connection, up and down reciprocal movement of the piston is converted into rotation of this axis. And from this rotation we can go everywhere else. We can go to the wheels to basically make them rotate and we can go to the generator which generates electricity. So, the purpose of this lecture actually, a very simple lecture is just to remind you about this formula that all we need is rotation. If you have a rotation, then using the magnet and the frame, we can have this generator of electricity. And generation of, well, producing a rotational movement of generation. Producing a rotational movement can be done in many different ways. And that's what I was trying to present today. If you already have some movement, some kinetic motion, this kinetic energy which is in this motion can be converted in different ways into rotation. So, we have certain natural motion like rivers or falling water in the waterfalls over the wind. So, we can use the propellers. We can artificially create movement of some substance like steam for instance and use this movement of the steam which we generate using the heat against the turbine to generate rotational movement. Or we can use the reciprocal movement in the internal combustion engine to convert it using this device into rotation. So, these are obviously not all possible ways to convert kinetic energy into electric energy. But it's just one of the major, probably, ones. And that was the subject of this lecture. So, again, this is how we are connecting kinetic energy, which we already have somehow, somehow else, we are obtained kinetic energy. In a natural way or we are artificially created, et cetera. How to convert kinetic energy into electricity using rotation. That's basically it. In the next lectures, we will talk about other ways not related to these purely mechanical devices and electrical generator and this type of basically formula, magnetic induction. So, we will talk about different ways to generate electricity. Now, what do I mean generate electricity? Well, to separate electrons from their hosts, from their atoms where they were located, thereby creating the difference in potential. So, there are different ways to do it. One way is electrical generator, which is basically using the rotation of the magnetic field. And there are other ways, not only related to magnetic induction. Okay, so that would be the subject of the next lectures. And I do suggest you just to read the notes for this lecture. There are some pictures, as I was saying. And I didn't mention it, but the physics of a team is part of this Unisor.com. Unisor.com is an educational website where you can find mass routines and some other courses. The site is completely free and there are no financial strings attached. You don't even have to sign in if you don't want to. But there are some exams on the site. So every lecture has accompanying notes for the lecture. And certain group of lectures usually have exams. So you can go with exam and you can take exam as many times as you want until you will get the perfect score. That's it for today. Thank you very much and good luck.