New concepts? Or was it all like you've done it in school? It was just a refresher. I can't hear you. Hello, can you hear me? Can you hear me now? Oh Yeah, I can't hear now. Okay. I asked if the pages you read was anything completely new or did it seem like everything you kind of remember you learned in school, it was just like revision? You mean 26? Yeah, I've seen learned this before. Okay, then that's fine. That's fine. Just because if anything was new, it would be more important for me to bring it up again later since the first time you see something is less likely you remember. But if it's the second time you've seen the things is you probably remember it better. Okay, okay, let's do this page then. Circuit devices. Circle. Ldr is a show light. An idea is a. With a. Resistance than is a dependent on the instead of light, just the code in the name. They have lots of politician matical nioutdoor lighting and turns the of. Where are you? The Green box? The. What mean the semester? The Mester is a device. It's like the it's like the ldr, but it's it changes its resistance based on temperature instead. Ammatmister. Interesting interesting. The ster Mr some momake useful temperature distance a car and temperature and. You've seen so misters, before, I think in our very first session, we did just a picture. Yeah, it's a symbol on the right this one. One. Yeah I see before the question but without. It's the device that changes resistance based on temperature. We learned about it in our first session. Okay? It was a long time ago, so I didn't I didn't blame me. If you forgotten, you can use. The can be used to turn or increase power the compedepending on the change. That they the circle below is a circle used to be control and fine, good. Wow. Okay, Yeah I just. I don't know how to say this word. Control a fan in the room. To control a fan in the room. I don't know the mean. We've got. Is this? Oh, fine, it's long time not say that. Yeah, because it doesn't really get that hot here all. Control, find the room. The pd of the power well is shut out between the meter and the b of the fixed, and the fine is attending. To. The. To the resistance, the big of the resistance room of the P D, the. Potential difference potential. The potential difference on growth of the me and bike will also be. En. The of the because I'm need to take a small similar similar shell. 什么了。小。Of ed. Is just the same as potential difference. It's just. Okay after. The greater the p compared, the more energy gets it is with the thing that's. Do you understand how it split up the potential differences between the thermester fixed resistor and the fan? Yeah, I think so. Okay, that's good. You can also the you want to control other as there, or instead, for example, if you can the with the idea the pethere and the ball will be hiwith, the unk and the reits height. So ball, the would get. Ainternet蛋。And ideas are many. Application. They use syand ideas and just namto the example on the page. Oh no. For example, ideas are using some terms of the control, lower lung and shorter should stay open for is the light level snow changes in the restaurant controthe shorter or to to stay open for long than if the lead level was higher? How interesting. How interesting. I am no box. Yeah Yeah, Yeah, Yeah. The so it's that ldrare used in cameras. So do you remember what ldrhow they work? The resistance changes based on what. How what affects the resistance of an ldi? Oh. What's? Application. So it's certain that semesters and ldrs have many uses, applications, different things it can be used for. Okay. Do you remember what lds stands for? Yeah, I remember. What does it stand for? Stern. Yeah. We are. Oh. It's to control. I don't. You can do this one first. R what is this word? I think I remember. I think it's a light. Yes. You're right, no difference. Rest her. Yeah, resisted. Exactly. Oops, exactly. So knowing that an ldr is a light dependent resistor, let's get back to the question I asked before. So what affects the resistance of an ldr? Keep on the light. Yeah the light, right? The light intensity and effects, it's resistant. So in this application where it's saying for camera shutters, how long they should stay open for when when the light level is low, you want more light to enter the camera because there's not enough to be able to see what's happening. So you want to be able to detect how much light there is. And then based on that, decide how long the camera Shuter opens for. So that's why they use an ldr because this can this changes based on the light intensity. So with this, you can change how things work based on light intensity. That's cool. Yeah, it's pretty cool. So it's similar for a thermester. If there's any application where you need to change something based on the temperature, then a thermester would be useful, right? Yeah. Yeah, awesome. Okay, that's cleared up now. We. The series circuits. Okay. Next, okay. Serious cycus her circles are just big lumps. In circles, different are. Well joined. Join together. Magnetic. Not. Acted uncounted. May, how does connected? I'll do a night take. Okay, I got it connected connected okay Yeah. In. We and we of the power. So this is showing the positive and negative of the power supply. They just wrote it in a different format. If you remove or discount, one pothe circle is broken and they all stop walking. This. Is annot very handy? And in state very form things. I. Okay, this circle can be used. Things are. Especially especially from for for my my. Suring ing. You can use the following readto and this game with. Can? Be used. Just for. He information. And. And. Okay, release and circle circle. Politician difference are title pd of the is shared between the ting, the round, the circle and up the end. That makes sense. No. Okay. So it's talking about the potential difference, which is the same as the voltage, right? Voltage. Yeah potential difference is the same as voltage. So it's saying that for a circuit in series. All the voltages along the series I circuit, we'll add up to the total voltage. Yeah. Yeah, okay. So if there's like the battery is here. That means all of these other components, the total voltage of these should equal the voltage given by the battery. That's for series seconds, okay? How this box current. Correct. Yeah. The sun haven't flows into all tent. The size of the current is between by the total pity of the coand the hydroresistance of the circle. I'll equal we by Oh, I know this, okay. Resistance of the cirwith the of the resiof the competent Yeah, I got let me test you on that. So we'll have a circuit. Let's have a circuit. It's the battery. This is a. What can we put here who resist to. And. Just put Mr. Okay, so this has the voltage zero. But I put a voltmeter on it. This is a voltage of zero. I mean this, the value of this voltage is v zero. And then the value of this voltage is B1. Value of this one is V2. And this one is V3. So can you give me an equation which relates b zero V1B2 phthree? Try not to look at your book, try to figure it out yourself. They give me an equation which relates these. They know. That's question again. Give me an equation which relates to these four turns. 没。Yeah. No, I help. Okay, so where is the source potential difference? So the one from the battery, which one is the one from the battery? By we no, this is a thermister. B3 is a thermister. So which one's the battery? Two, well, which ch symbol into the battery? Maybe maybe it's one. We one. Yeah Yeah, we one. Okay, V1 would be this symbol. Do you think that is a battery? Why not? Because you know what it is. You know, I get three wrong on one, right? Zero. Yeah so do you remember this is a battery? It's hard, remember? I think I'm no runma, right? Okay, that's quite important. Okay, wait a minute, let me. I can't. You need to be able to identify all of these. I'm going to paste them all so that you can try and identify them now. Okay. Don't we start trying to identify them, okay? You can draw like a you can draw an arrow and then write what it is. I can try to everything. First is hell, second is a write down down. It's horrible. 嗯嗯嗯。Button. Is. By three. There is. And the switch. What's the difference? One is open with close. Love. And boss. And. Add day. This is a resistor. This. Is it? I'm just going to put that this is very able嗯A那ok。Only five left. I know how to say this, but I feel how to travelthat's. Okay, just try and I'll correct you. It is. Almost. It's a. Well, not. Yeah. Doubt. And. They are. I'm this, I don't know, you do know, you do know we just did it. I don't know. We just read about it. You definitely know when try and guess it, I guess is I think it's. Okay. Yeah, exactly. I missed it. Okay, awesome. Well, it's felt with an o, but I think you spit with an o. Yeah, nice. Okay. So you do recognize the symbols. You recognize all of them was because my drawing is bad. Is that why? Lewhy, are you able to identify it here when not in the diagram? Is a switch. There's no switch. So in the diagram, I drew a battery like this. I drew a lamb like this, add you resistor this one. And I drew thermester like this one. And then these are all voltmeters. Right. Do you see that now? Okay. So the battery which one which voltage is the batteries voltage then? Justin, I train. I think it's Oh. Exactly. V O, Yeah, exactly. V zero. So the voltage from the battery is all the all the increase and and the other components should all decrease the potential difference, right? Yeah. So in a series circuit, so series circuit where they're all linked up like this, in a series circuit, this will be equal to all the components added together, B1 plus B2 plus B3. Yeah. Does that make sense? Yeah, okay. What about the what about the current through this component versus this component versus this one versus is this one if we label it if we label it like eyes or our eye is current. How do they how are they related? Like I 1:10I equal I three and minus one I four. Like that, right? Yeah, yes, voltage in a series circuvoltage adds together between components and the current is the same across all places. Yeah, perfect. And what about resistance? So if we had resistance three, resistance, for what am I doing? Sorry, resistance two, resistance one. And let's say that resistance t is the total resistance of the circuit. Sorry, there's a resistance in the battery as well. How would you relate? R zero, R one, R2, R three and rt, this is the total resistance in the circuit. Okay, terrory resistant, equal als resistant. Plus one is two, plus one is two, plus 164, plus 165, plus 166. You keep going. Okay? Yeah, okay, that's important. Nice. So it's important, you know how the voltage relates, how the current relates and how the resistance relates. And this is only for a series second. Okay, let's continue reading and then we'll move on to the parallel circuit afterwards on the next page. That's good. That's good. That you could identify that. Okay. You can read on your other red books. Red books this is because when two resistors are connected in series. This is because when two regior the they have to share the title d. The coator defense occureach resistance is lower. So the crisis each resiis also. Raccircle the. From everywhere, so the title can contract in a circle. It's rudict when the is a date, this is mean the title resister of the circle as instance bigger among a compound resistance, the bigger it is shof the title protein different. Example with. A circle drabelow correct. Conthe licencircle first one title, racism by adding gathe resistance of the two resithen religion times items, vehicle items are or I in the values your. So putting different island up with a certain current, so is big and win more clouare in. Is there the same way, for example, when two a percent depends for one, five, I connect with things by spthree way. Between them, three circles are used very much in the once you sing your your head around, test yourself with the question below. Oh Yeah, I think you should. I don't know. I think it be, it won't be that difficult. I think even. I don't think so. Yeah, I don't think so. Why? Well, all do you say? Why don't you don't think so? I don't think itbe difficult. Oh, it's no difficult. I don't think it's not difficult. You'll be fine, heavy. Oh, it is. It's no difficult. It's. Like four plus five plus six equal 15 and Oh zero six zero six times 15 equal nine so as is nine finish. Yeah it's no hard right. 7.6, ten set is like nine watts. You need to put the units nine v, nine v. Nice. Okay, hopefully let's try and read about parallel circuits. We only have nine minutes, but hopefully we can finish it. Really what the next page or okay, actually you get two options. Either you can read the parallel circuits page or I can explain to you how how the current resistance and voltage work like this, like drawing it. Which one? You second one, I'll explain it then. Have you seen parallel circuits before? No, so instead of instead of it being lehave a lamp and let's have the same things, a resistor and a semester. We have the same things in series there like this and they're all connected in one big line, right? That's in series, right? Yeah. But in parallel, it will look like this. So instead of all being in one line, they're on different branches. Yeah, okay, so. In this case, let's do voltage again. Fast voltage one, voltage zero, voltage one. I'm not drawing the voltmeters, but you know that if you were to measure the voltage, you would put like a voltmeter here, right? You know that? Yeah, Yeah. So I'm not to draw those because it it's just a bit messy. So how do you think these four are related? The four voltages are related? What's your first guess? It doesn't have to be right. I'm not expecting it to be right because you haven't done this before. I just want na see what your guess is. I'm not really sure. Okay. So what it would be. Is this? Oh equal equal Yeah Oh equal. This is because. Like these are the electrons with their different potential energies, I mean, different potential. Each electron has a potential difference. And when it's moving along the wire, when it gets to this part, they like they go off in their own direction. But the potential difference, like the height of them, remains the same. Right. Does that make sense? Yeah. Still it goes. Now let's look at the current. And I stood it in pink. What do you think happens to the current with what I explained to you just now? Remember that current is the rate of flow of charge, which means like the rate of flow of electrons. Parents. It's like equal like cat one equal ten, two, three. Okay, that would be correct if we looking at a series second like before, right? That's how it was for series second. But in this parallel second, let me get these these electrons out again. The rate of flow of charge right now is going to be, let's say this is how many is in actually, let's make it easier and just D3, let's say this is how many how much charge goes through per second? How much charge goes through per second right now is three, right? But then when it splits off. Per second. There's only going to be one in each branch, isn't it? Because they've distributed themselves, right? Yeah. So with that information, what do you think the formula is? Do you have any idea? Okay, so because they split off, that means that the original one is the sum of these three branches instead therewould be I one, plus I two, plus I three. Yeah, Yeah. Okay. And then the last bit is resistance. This one is a bit more like not very intuitive. So I'm just going to tell you. But how these resistances are related. Is that the total resistance actually? Okay, let's ignore let's ignore that one for now. By total resistance here I'm going to mean this whole section. Yeah, Yeah, okay, okay. Total. So resistance that's actually. One over total resistance equals one over R one plus one over R2 plus one over R three. Yeah. So this means if you were to work out the total resistance, you would have to do. One over one over R 11 over R2. Yeah, Yeah, okay. Does this all make sense? Yeah, nice. Okay, I will. I'll show you some homework. I think we're not going to see each other for quite a long time. So. I'll set you homework for the next week, but after that, just to make sure to keep going through the textbook, you can set yourself how much you want to go through, but try and keep working through that. Yeah. Yeah. Okay, okay, awesome. I'll see you later today. Anyway, for biology later. See you. Bye bye.