Alright guys, let's go ahead and get started here, because I have a little demo I'm going to do today. So today the theme of the class is going to be setting up and solving problems that involve capacitors. And of course you have Homework 3 do right now. So Nush and I have discussed how we're going to manage grading this because she works all day Thursdays and can't come to campus. So what we're going to do is I'm going to make digital copies of the problem that she wants to grade on Homework 3. And then I will put the homework solutions you guys have handed in back in a folder in the physics main office. And I'll send an email where you can pick them up and you can pick them up at your leisure. So it'll be on the very front desk and you walk into the main office which is room 102. Okay, so just at the end of the hall here on the right. There will be a desk to your left. There may be a student worker there. It's staffed usually by a student worker. It will be like a tray labeled Sakura Physics 1308, something like that. And there will be a folder in it.  I got so backed up this morning I couldn't record your scores on the previous quizzes or the score from Homework 2. So there's going to be a big pile of stuff including Homework 3 that's going to be in there for you. So look alphabetically by last name through and make sure you've got all the things in your section of the alphabet. Okay? All right, so any questions on that procedure? So again, that's how we're going to get things back to you as quickly as possible. Any? Sorry, I was a bit worried about it. Can I find it? It'll be in an email but physics main office is where it's going to happen. So don't go there yet. There's nothing there yet. But I will announce it to the class when everything's ready to pick up. So I'm going to spend my afternoon getting all the grades reported and then getting all that stuff digitized for NUSH. And then once that's all done it will all go in the main office. So I'm hoping before I have to leave it for today everything will be in the main office for you guys to pick it up. So, all right, so there we go. All right, so a few concepts to keep in mind. Electric charges exert forces on one another via the electric field. That field is always present as long as there's a charge somewhere in the universe. Whether or not a charge is there to be acted upon. Okay, so all you need is one charge and then you get an electric field. There don't have to be any other charges for the field to exist. That electric field just like gravity is a conservative force field but you have to think a little carefully about what the potential energy looks like for different kinds of charges moving in different directions because there are two kinds of charge. There's only one kind of mass that we know about in gravity but there are two kinds of charge you have to deal with when it comes to the electric force. The field comes along with an associated energy per unit charge. This is known as its electric potential and in fact this is really the more fundamental object in nature. So far as we know every force that we've ever discovered can be described very successfully with this concept of a potential. So an energy per unit something. By understanding how charges move in an electric potential we can understand how energy is stored in the field. So again boiling it down to that fundamental concept of energy. Alright so you do have an assignment for next class. All that will happen in next class is that you'll have a quiz on this assignment at the beginning. So you need to keep reading chapter 25. We're going to finish up capacitors and you're going to watch the rest of that video you started for this class. So you're going to go from about the 42nd minute until the end. It's about 12 or 15 more minutes of video by electrics which we'll touch on a little bit today even ahead of having actually had to watch the video. And then there's an additional piece here you should go and watch as well. Homework 4 will be due Thursday October 1st. So it's assigned today, should already be in Wiley Plus and then there's a paper copy, a digital paper copy on the class assignments page. There is a problem that I've written tacked on to the end. That problem was actually inspired by a question from a student in honors physics. So you get to reap the benefits of their curiosity. How's that sound? They were curious what it would take to capture the energy of lightning and store it. So you're going to do that by exploring the concept of a supercapacitor. That is due in two weeks from today. So your primary focus for next week should be preparing for exam 1 which will cover the materials covered on homeworks 1, 2 and 3. That exam will be in class. It will be 80 minutes of allotted time. My goal will be to write an exam that an average student in the class, whatever that means, can finish in about an hour. And that leaves about 20 minutes or so to kind of go back, think about things that weren't clear, maybe you only got partly through a problem and you want to go back and touch it up a little bit. So that will be my goal in writing the exam. It will be a mix of multiple choice questions at the beginning which will be some fraction of the grade and those will test on concepts in the same style as the quizzes and class. And then there will be, you know, two, maybe three, depends on the length of each problem, with two, maybe three problems that you have to solve after that. And we're going to practice this in class on Tuesday with an in class kind of dry run of a part of an exam. Okay? Alright, so as I said, we will have a quiz on Tuesday morning on this stuff. So don't skip this unless you just don't care about the quiz.  So if you really don't care about it, that's your business. And I'm not going to tell you what to do, okay? I'm just warning you, there's a quiz at the beginning of class on Tuesday. Alright, so any questions on this stuff? Okay, Shannon, then Sophie, then Israel. Yeah. homework three? I don't remember the exact one. Yeah, but you should be able to go look at the class materials page and kind of figure out what sections were covered on that. So it will cover basically up to the beginning of sort of electric potential energy and electric potential difference. But to find the crystal boundary, you know, take a look at the chapters that were associated with that homework stuff, okay? There we go. Alright, so, moving on. Oh, sorry, Sophie. So we don't care. Sorry. I'm really tired of that. We know we're being quizzed over Tuesday or on Tuesday over the capacitor stuff. It's not going to be on the test solvers. That's right. Okay, so, treat it as you see fit. Okay, Israel runs out. Yeah. So for the following exam covers homework sections, one, two, and three, right? And also see the quizzes that went with that. Quizzes as well. Yeah. Once reviewing for all of those, do you have, like, maybe an extra, like, maybe, like, you could pick out certain questions that might be similar or irrelevant to the exam? Well, the ones that I write myself will be obviously very close to the style of what I give you on the exam. And in fact, sneak preview, the bonus question you had on integral calculus for Coulomb's law was taken straight off of a previous exam from, like, last semester. Okay? So, there you go. Like, there's a softball pitched right at you. So, like, the style of thing you might have to do. Okay? Yes? So, so, the formula should be given the day of the exam? Well, so the formula sheet, I'm actually going to beta test on you guys on Tuesday. You're going to give me feedback on Tuesday if there's other stuff you'd like on it. And then that will show up on Thursday. All right. So, you get to beta test the formula sheet on Tuesday. Okay? Yeah. That was my question. Okay. Great. Yeah. Okay, any more? All right. So, Grant? Yeah? Sorry. Okay. Grant, challenge problem. So, thanks to all the teams that have turned in minutes so far, they've been very helpful. It's good to see people are sort of bubbling up ideas that could be pushed forward as we go through the semester. The first team meetings with me are going to be planned for this range of dates starting next Friday, the Friday after the first exam, going through the following Wednesday. So, lead editors, watch for my emails with sign-ups for meetings. I'll start sending those today or tomorrow. So, you can query your team and find out if there's a time slot that works well for most people or everyone. Okay? It may not be possible in that limited range of dates to get every member of your team in, but our goal should be to try to do that. Okay? And you'll get a dedicated 30 minutes of time to discuss so far like what's been going on. Okay. So, here's what I had so far based on going back through all my emails that I could find. All right? So, Team Alpha, we're now Coulombs. We got the Fig Neutrons. That'll look familiar to some people in honors physics. Law-abiding Physicists, which is the most upstanding team name we've had so far. Team Delta. You guys, I don't have anything from you. So, Weston. Oh, I did. Okay, great. I'm dropping the class. Oh, okay. All right. Now I'm really super sad. Okay, all right. So, yeah. So, let me know what you decide, and we'll have to maybe take a look at your team size and figure out what to do. But I designed these problems to be something that could be accomplished with as few as two people per team. But I think you're down to three after this. So, okay. So, you're fine. You're absolutely fine. Okay? We had a team last semester that went down to two by the end and they did fine in the class. So, okay? So, no big deal. All right. So, Team Echo, the Dolphins. Is that a reference to the video game of the Dolphin? Yeah. Wow, I'm actually pretty impressed by that. That's obscure. Okay. That's, I mean, I don't even know what to do with that. That's so awesome. And then Team Foxtrot, Faraday's for Days, which to me is the most perplexing name of any team that I've seen so far in two semesters of doing this. So, hey, you guys can do what you want. I don't think this is a euphemism. So, I think we're good. All right. And so, everybody has a lead. Editor assigned. I don't have minutes from Faraday's for Days yet. I do. Sorry. That one's wrong. Which one is it then? I think it's... Oh, it's the Dolphins I don't have minutes from. Okay. Sorry. I put this on the wrong thing again. I was very tired this morning. So, all right. So, that goes there. And I do have Faraday's for Days. That's true. I keep screwing Team Faraday's for Days on. I'm like information here. I apologize. I apologize. Apparently, I have something against you guys. I don't know what it is. It's a subtle bias. Okay. So, any, anything here? Okay. Let's do the quiz then. Over the quiz questions. So, question number one. What is capacitance? Is it one, the total amount of charge placed on the capacitor? Is it two, the energy stored in the capacitor? Okay. Is it three, the constant of proportionality relating the charge on either plate of the capacitor to the electric potential difference voltage across the capacitor? Okay. Some takers there as well as on two. The constant of proportionality relating the potential energy to the work required to place all the charges on a capacitor. Okay. So, the answer is three. It's a constant of proportionality. So, basically, if I have a device with one conductive side and another conductive side. If I have conductor, conductor, and then in here we have insulator so that charge is not free to move across this gap. Okay. So, there's a gap here. If charge is not free to move but can be piled up over here and piled up over here with opposite sign, this is, this is a capacitor. Just taking charge and separating it from one another. So, it's like a super dipole. Okay. The capacitance is simply the relationship between the charge I can place on either plate and the voltage that results, that electric potential difference between these two sides as a result of the field that's created in between here between the charges. So, this thing here is capacitance, quote, unquote, and it has a unit which gets a name, Farads, or F, very close to your name. Okay. All right. So, Farads, F, and they are simply coulombs per volt. That is a Farad. So, one Farad is one coulomb displaced across one volt of potential difference. That's it. So, Farads are coulombs per volts and they can be related to other units in meters, kilograms, second to coulombs as well. All right. So, let's go to the next one. So, let's consider a parallel plate capacitance. It looks just like this. With plates of area A and separation D, what is true about the capacitance if I have that is reduced by a factor of two, the separation between the plates? Okay. So, there's a formula for capacitance for this particular geometry, a parallel plate system, this thing right here. All right. So, it is the answer one. The capacitance remains unchanged. Is it two? The capacitance increases by a factor of two. Okay. A few takers. Is it three? The capacitance decreases by a factor of two. Okay. Is it four? The capacitance decreases by a factor of four. Okay. So, the answer is two. All right. So, for those of you that had hands up for that, good instincts. Okay. The formula, which I'll repeat again in a bit, is that the capacitance for a parallel plate capacitor system is a constant of nature, which I'll talk more about in a moment. Epsilon knot. Epsilon knot you may remember from a long time ago is related to this K constant we've been using this whole time. K is equal to one over four pi epsilon knot. So, you can rewrite epsilon knot in terms of K. Okay. So, epsilon knot equals one over four pi K. All right. And it turns out that's the more fundamental constant of nature.  So, it's not that much more fundamental. But this is the one that pops up in a bunch of places as one moves further and further along in electricity and magnetism. And there's a very good reason for that. And we're going to begin to see that reason illuminated inside the capacitor. So, you've got this constant times the area of the plates. So, the plates will have area A in meters squared. Three. And there'll be the gap separation D, which is in meters. So, if you double the area, you double the capacitance. If you double the separation, you cut the capacitance in half. If you have the distance between the plates, you double the capacitance. Okay. So, that's why that happens. It's a proportionality issue. So, you know, building some comfort with this equation, which ain't a bad equation I have to deal with, is a good thing to do just to get a feel for what happens to a geometric system that can store charge when you change its geometry. Okay. And finally, what was true about the electric field inside the ideal archetypal parallel plate capacitor discussed in the lecture video? So, basically this, but imagine the plates are super big compared to the gap in between so that you can ignore the weird effects from the electric field fringing that might happen near the edges of the plates. Okay. So, what was true about that field? One, it is strong next to both plates but very weak in between them. All right. So, it's really strong here and here, but it's weak in the middle. Okay. Two, it's uniform in strength between the plates. That is, it has the same direction and magnitude everywhere in between the plates. Any takers for two? Okay. Three, it's stronger next to the plate containing the negative charge. So, if this was plus Q and this was minus Q, it would be stronger next to the minus Q plate. Okay. And then what about stronger next to the plate containing the positive charge? So, this one over here. Okay. Everyone's tired just like me. All right. So, it's uniform in strength between the plates. And in fact, a parallel plate system like this is a great way to make as close as we can in nature a uniform electric field. So, no matter where you are inside this thing, the field strength is the same and it always points in the same direction. Okay. So, capacitors are really the simplest way to make a functional device that lets you do this. Okay. So, we're going to now engage in some problem solving with capacitors. But before we get into the actual problem solving, what I'd like to do is I'd like to review the basic ideas which are kind of sketched up here. Just one more time so that they're fresh in your mind and you can use them. Okay. And then I'm going to demonstrate capacitors because we can actually play around with one in the classroom. Okay. So, the basic idea is, as I said, a capacitor is merely a device. It's the first useful electric device that we encounter in the course. And it can be actually used in all modern electronics. All modern electronics uses capacitors in one form or another. It's simply a device on which you can place charge, net charge. And as a result of having that charge present, it will develop an electric potential difference that is proportional to that charge. So, that's what that equation says. The charge that develops is proportional to the voltage. The voltage generates a charge separation which is proportional to that. Okay. Either way you want to read it. That relationship is this nice equation here, Q equals Cv. Okay. The way I used to remember this, although I'm not sure this is really helpful anymore because I really doubt any of you really watched TV the way I watched TV when I was in college. But there was, and I believe there still is, a channel on cable called QVC. It's a shopping channel. And that's how I used to remember this. QVC. So, Q equals VC. That for me worked. All right. But you may have to have another mnemonic that works for you in the modern world. So, I'll leave it up to you to cook up some poem, rhyme, song, whatever it is that helps you remember these things. Now, a very simple capacitor that we can actually learn a whole lot about capacitance from is this idea of a parallel plate capacitor. One plate, another plate, insulating material in between, separated by a distance, plates of area A. Okay. The simplest thing you can do to put an insulator between two plates is to suck all the material out from between the plates. So, have a perfect vacuum, absolutely empty space so that the charge can't be soaked up by anything and carried across the gap. Okay. That's the most basic archetypal ideal capacitor. Plate, plate, nothing in between. The capacitance then is calculated exactly using this equation. So, the capacitance of this picture right here is this constant, epsilon naught, which always has the same value, times the area of either plate divided by the separation between the plates. So, if you know A and D, you can get C and then you can use that to figure out, well, if I want to store so much charge, what voltage would I have to put on it? Or if I have a battery that supplies a certain amount of voltage to that plate, what charge do I develop on it instead? Yeah, Darson. Is it possible to have two different areas for the plates? You can, but then the capacitance would be dictated largely by the area of the smaller plate because what will happen is, let's imagine that. Let's imagine that you have sort of a big plate and a small plate, all right? And if we were to put a bunch of positive charges down here, this would cause an electric field to lose the gap, okay? And again, we're dealing with situations where the plates are big compared to the gap, all right? So I'm not really drawing this to scale, but imagine that the plates are much bigger than that space between them. I'm just exaggerating the space for effect, okay? Over here, negative charges will develop. They'll be attracted to the positive charges and positive charge will be repelled by the field. And because there's going to be a little bit of leakage of the field out to here, you'll get some charge out here, but most of it will be concentrated above the lower plate. So that's not a very ideal situation. It's far more realistic. I mean, it's tough to engineer things to be exactly the same size. But as long as you do it within this approximation, that the space between the plates is much smaller than the plates size themselves, you can kind of get away with making this approximation all the time, okay? Now, it's a good question. So that's a much more realistic situation. And in fact, you might be able to design some interesting systems by going away from perfect. Going away from these perfect archetypes we use in physics, introductory physics to motivate things is a good way to design new technology, okay? Because all kinds of interesting things will happen. And you can understand all of them. You can computer model them using Coulomb's law and the other laws of electromagnetism that we're going to learn as we get through the course, okay? All right. Now, I should say, and we will do this a little bit later in the class, you don't have to stick nothing in here. You could just stick an insulating material, glass, air, air is an insulating material, ceramic, all kinds of neat things have been made by humankind in the last century or so, all these new cool materials we have and mostly driven by the need to improve electronics more and more and more, make them smaller and smaller and smaller, make them do more for the same voltage, okay? So, the material that you stick in here is known as the dielectric, and a dielectric is an insulator, and an insulator is nothing more than a medium that when exposed to an electric field will suddenly expose its dipole nature. So, think of water, right? So, if you have a block of water, we know that the water molecules are really dipoles, but they're normally oriented randomly, but if you expose the water block to a really strong electric field, the dipoles will do what? What will they do along the electric field lines? Yeah, they'll rotate and maybe translate depending on if the field's uniform or not, but we know that the dipoles will rotate, right? You have that sort of in the last homework. So, if the dipole starts off perpendicular and a field occurs, you'll get a torque that rotates it so that the dipole moment is lined up with the electric field. The negative charge moves away from the electric field arrow, the positive charge moves toward it, and the whole thing kind of rotates. When you do that, if you work through the math, what you'll find out is that the dipole weakens the electric field in the region around it. So, that's why insulators insulate. They weaken external electric fields, and they don't allow charges to move as much as they would if they were just exposed to the raw electric field. So, we can get some super dipole material and shove it in here that really weakens the electric field so we can pack more charge onto these plates. So, that's how you can store more charge, shove a dielectric in here that weakens the electric field in between. Different dialects have different properties, something like graphene. It's really stable, and insolent as all of those are all carbon-based. Yeah. Graphite, for instance, is a cheap version of graphene. You can make graphene from graphite. So, graphene is a literally a one atom thick layer of carbon atoms arranged in a very specific lattice shape. It's a really sweet material. It's discovery, which was largely an accident, won the Nobel Prize a few years ago in physics. Does anyone know how graphene was discovered? I mean, essentially, if we really want to boil the story down. So, what was going on was that the researchers were using scotch tape to lift off carbon from a graphite sample, and they at some point decided to ask, I wonder what we're pulling off when we yank the scotch tape off and throw it in the garbage. So, they studied what was going on on the carbon atoms that were trapped on the scotch tape, and they found out that they were making essentially a perfect monolayer of this new material called graphene, and it has all these really cool, tunable, electronic properties. They've actually they've been working with companies now to develop printers.  So, what I would love is I would love to have a printer in my home, which is just loaded with graphene cartridges, and you could go to the computer and say, look, I want essentially to print a pay for a copy of the latest Nexus 6 or Nexus 5X or the new iPhone or something like that. So, you just go buy the schematics from the company, hit print, and it will print monolayers of electronics including the case, the circuit board, the screen, all entirely out of graphene. That's what they're trying to do, and they printed simple circuits doing this so far. But, you know, imagine in 20, 30 years, given the rate the technology accelerates in its advancement, you should be able to print your own custom electronics at home. So, yeah. So, how can graphene be used in a medical application? Like, can it be used for, like, CAS, or... Oh, well, that's a good question. I mean, you might be able to custom print a pacemaker. Right? But, of course, you're not going to install that yourself. You're still going to want a qualified surgeon that graduated from the pre-med program at SMU to cut you open and put that inside you. Yeah. Also... Come on, I know I'm getting old. I'm going to die, and I need you to cut me open at some point and fix me.   This is good. Oh, like, based on, like, biological material? Keep that in mind. We're going to talk a little bit more about that in a moment. So, yeah, capacitors actually play an important role in biology. You'll see one in a moment. So, hold that thought. We can talk about it a little bit more later. Okay? Any more questions at this point? Because I'm going to go demonstrate. Okay? So, let me begin by quitting this video camera. Bringing up demo camera. All right. So, everybody, try to behave themselves. So, what I have here is a, well, and I say everybody, I really mean you. Okay? What I have here, like I said, will work. There we go. Is a volt meter. So, it's a, it's actually a, what's called a multimeter. It can measure electric current that is charged per unit time moving through a circuit. It can measure electric potential difference or voltage. It can measure the resistance of a material to the flow of electric charge, which we'll talk a bit more about in a few weeks. Okay? It's an all-purpose electrical tool. And I'm going to use it today to measure electric potential differences. So, electric potential differences we're all pretty familiar with them. Okay? In the sense that there's one in, many of them in every room in a building that you go into these days. Let me switch this to alternating current voltage.   Okay? So, if I do this. Okay? You'll see that we're getting an electric potential difference, as promised. That isn't a magic box that has little fairies in it that go in and power your lamp by paddling bicycles and running into atoms. Okay? And giving off light with flashlights. No, it's an electric potential difference. It makes electrons go. That's it. Those electrons crash into things and when they crash into things, they give off energy. And that's how light works. Okay? You're told that typical voltages in buildings are about 110, 120 volts. You're enough about 120 volts. Okay? So, there's an electric potential difference there. I'm going to take that out. Now, we're going to play with what's called direct current today, where what's going on in here is that every 120th of a second, the direction the current is traveling switches. And there are a lot of reasons why you would want to do this for efficient power transmission over long distances. This device takes alternating current and turns it into direct current. Current only ever flows in one direction in this device. And it has electronics in it that we'll learn about later in the course that take that 120 volts and step this down to about 6 or 7 volts. Okay? So, I can turn on this power supply over here and I can plug in the voltmeter part of this here. All right? And you see, that's what we're getting out of this. So, this is now direct current. DC voltage, DC direct current. AC alternating current. AC DC, an awesome bend from the 1980s. Okay? No? You know, echo the dolphin, but I don't understand. This doesn't make any sense. All right? So, 6.39 volts is what I'm getting out of this power supply. Okay? So, that's what this thing is called. It's a power supply. It's a battery, essentially, that's generated by plugging into wall voltage and it transforms the voltage into something else that could be useful. All right? So, you know, you could use this to, as you, what's the voltage that comes out of USB, micro USB? It's like 5 volts or something like that. So, this could charge your mobile phone. You know, just a couple of hours, your phone could be charged up. This may be less depending on your phone. So, this is perfectly useful for all kinds of household things. Imagine that you wanted to use this to build up charge someplace and store it so that you could use that charge later for some other kind of work. It could be hours from now. It could be microseconds from now. That's where capacitors come in. All right? Capacitors allow you to store up charge for an emergency or for some other purpose that might be useful in time, but not right away. Okay? So, you can stop for a little bit but there may be all kinds of ways you want to slow charge down over time and then use it later. We'll explore one of those in a bit, you will. I'll talk about a useful one and then you'll look at another useful one. It's even more fundamental than the one I'll show you. Okay? So, what I have here is a capacitor. Now, this is like my granddad's capacitor. Okay? Maybe my great-granddad's capacitor at this point. This thing is huge and it really doesn't have a lot of capacitance. Here, let's see if I can get it to focus. That would be freaking cool. There we go. You see, it says 10,000 UF. 10,000 UF. That sounds really big. 10,000 UF. Well, that U is actually micro. Okay? Because they didn't print Greek letters on these things. UF was easier to print than UF. Okay? So, it's 10,000 microfarad or 10 millifarad. All right? So, this is a 10 millifarad capacitor. That doesn't sound so big. Okay? I can hook it up to an electric potential difference like this one and I can store charge. And by storing charge, I can retain the electric potential difference in the capacitor. So, it doesn't really matter which way I hook this up. We'll find out. If this blows up, this will be fun. So, I'm going to let that sit for a moment and I'm going to now hook up my voltmeter to the capacitor. So, ground high voltage. All right, it's 6.26 volts. All right, let's go back over here. Got ground, high voltage. 6.27 volts. These are the same potential difference within the error of this equipment, which is in the last decimal place. Okay? So, I'm going back to this guy. Just check it one more time. Okay? The power supply from the capacitor. All right, so let me see if I can do that in one fell swoop. We'll let that sit a moment. Now, in principle, if this device is capable of storing the charge that is built up on it, when I disconnect the voltage from the capacitor, the charge is still in there. And so, it should still essentially be making that electric potential difference inside the capacitor. Let's see. 6.18, 1.7. We'll let that sit for a moment. 1.5. All right, so it's declining a little bit over time here. But you see, essentially, I've still got 6 volts stored in this thing. Now, I can carry it around. I can kind of walk this thing around the room and throw it in the air. Oh, yeah. You want to touch your tongue to this thing? All right, there are ways we can drain the charge off this if we were to do what's called short. Short. The leads between this. I haven't drank enough coffee today, apparently. I don't know where I'm from. If I shorted the leads, I would give a path for the charge to escape. So the negative charges, for instance, could recombine with the positive charges on the other side. So let's check in on our little capacitor, now that I've been throwing it around the room and threatening people with it. 5.96 volts. All right, so it's leaking away over time. Any speculation as to why that might be happening? Why would the voltage be decreasing over time? There's a lot of charge over here and a bunch of charge over here, and they're separated by a material. But eventually, we're watching this thing. We're watching this in the real world and the voltage is lowering. Yeah, charges are repositioning. If the V is going down, the C isn't changing. Maybe the capacitance is changing. Maybe something's happening inside that chemically. The capacitance is weakening. That's one hypothesis. But maybe an easier hypothesis and more likely one is that as V goes down, are there any such things as a perfect insulator, something that can absolutely and utterly stop all charge from moving ever? Yeah, it's kind of unlikely, right? I mean, we're in the real world. These are imperfect materials. This thing's old. So it's very likely that the dielectric that's present in this capacitor is not great. It's good, but it's not great. And so it's maintaining a voltage over time, but it's leaking charge across the dielectric. Little separated charges are finding their way home to their parent atoms somehow. Okay? We see we settle down to a comfortable 5.65 volts. Yeah. That's the same kind of concept of any kind of battery. Yeah. So it's not like an electronic decay or something. Oh, like radioactive decay or something like that? Well, that probably is happening in there. I mean, radioactivity is all over the place. But it's likely not the major culprit. It's likely just that a negative charge is escaping through the dielectric and recombining with an ion on the other side. And then now you get a little bit more neutrality in the system in another electron leaks across the barrier and then gets in there too. So, you know, materials are not perfect. Some conductivity will happen even in an insulating material. We do have materials called superconductors that will essentially allow current to pass with no resistance to movement whatsoever. We played around with one of these a little bit in honors physics last night. If you make a material superconducting by cooling it down, which we did with liquid nitrogen, you can actually float a magnet over it. It will just levitate above it. And that's because superconductors will not allow changes in magnetic field. So once you place the magnet in the presence of the superconductor, even if gravity is pulling it down, it will hold itself above the superconductor and it will levitate. You can knock it and it will spin almost frictionlessly. It will only have air resistance to deal with. So once the superconductors principle they float above the track, all you need are jet turbines to push the trainer to slow it down in the other direction. Okay. All right, so I can drain the charge off this, of course. So let me check on this one more time. We're at 5.36 volts. Okay. So I will now short the capacitor. I will hook its positive end to its negative end. Ooh, they got a little spark on that one. That was a good one. And now if we check this, a little bit of residual charge left, but not a whole lot. So I didn't drain all of it, but I drained most of it. Okay. And that's not going to explode, which is good. All right, so that's a demonstration of a capacitor. You see it as physically possible to separate charge and store it for a long period of time, maintain a voltage, and you can imagine using these for all kinds of purposes. So let's look at one of those right now. Almost right now. Okay. Portable defibrillator. Portable defibrillator. We explored this last time. We looked at it from the perspective of energy last time, but this time we can look at it as what it actually is, which is a large capacitor. A large portable capacitor. It can be powered by a battery or plugged into a wall. The portable ones are obviously battery powered, so you don't have to plug a cable into the wall. You can use this on public transportation, in airports and bus stations, in public buildings, in private buildings. I'm sure there's at least one or two somewhere around here within one building of us right now. Okay, they're very useful in case somebody goes into cardiac arrest because they can reboot the pacemaker in the heart. The job of a portable defibrillator is to store a very large amount of charge, and we looked at that number last time. It doesn't seem that big, but actually this is a lot of charge. That charge can be released across the heart to restart it. So you generate a current across the heart, reboots the pacemaker, and you can get back to regular rhythmic motions, rhythmic contractions of the heart, hopefully. So the way that you build up that charge is you expose a capacitor system in here to an electric potential difference, and in particular the electric potential difference that you typically would need to place a capacitor in here is about 2.3 kilovolts. That's the number we had last time as well. So, here's the cool thing. This thing has a capacitor in it, and each of these paddles is hooked up to one side of the capacitor, and it has a trigger on it. So you place the paddles across your chest, and your chest now becomes the path for shorting the two sides of the capacitors, just like I shorted the two sides of the capacitors there. So the reason you need as much voltage is that nobody offers resistance to the flow of electricity, so you've got to overcome that resistance and drive enough current through the heart to reboot it. Alright, so when you pull the trigger, you are basically shorting out the capacitor and connecting its two sides again. So the negative charges will move back to where the positive charges are, and boom, your heart will restart. Hopefully, if it's not too damaged already. So, the question is what's the capacitance required to achieve these conditions? A potential difference of 2.3 kilovolts where you have 145 micro-coulombs stored on each plate. So we can start attacking that question right away from the fundamental equation for the capacitor Q equals CV. Okay? So let's go ahead and write that down. Q equals CV. Well, we're given Q and we're given V, and we're asked to find C, the capacitance. So we're trying to find this thing. Capacitance. And it will have units of Farads if you have volts in volts and charge in coulombs. Alright, so if you get your voltage difference into volts, instead of millivolts or microvolts or kilovolts or something like that, and you get your charge into coulombs instead of micro-coulombs or millicoulombs or mega-coulombs or something like that, that what results from this one Farad is one coulomb and that's the definition of a Farad. One coulomb over one volt. Okay, well, let's go ahead and rearrange this. C equals Q over V, and this is going to be 145 times 10 to the minus 6 coulombs divided by 2.3 times 10 to the 3 volts. So just to do some number gymnastics with this, I've got a 10 to the 3 in the denominator. That's equivalent to 145 over 2.3 times 10 to the minus 6 times 10 to the minus 3 coulombs per volts. Okay? So all I did was I took advantage of the fact that this is in the denominator so dividing by a thousand is equivalent to multiplying by 0.001 or 10 to the minus 3. So I get 145 over 2.3 times 10 to the minus 9 coulombs per volts is Farads. Farads. So I'm nearly there and I just have to do that math. And just like on a cooking show, I've done it already. Okay? So you get 6.3 times 10 to the minus 8 Farads. Now it's often convenient to re-express this in terms of you know, some powers of 10 to the 3, right? Micro, Mill, Leapico, Nano, things like that. So this is equivalent to 63 Nano Farads. Not a big capacitance. This doesn't sound like a big capacitance, 63 Nano Farads. That sounds tiny actually to do that kind of amazing work, storing that much charge we dump through your heart to reboot it. Let's explore that a little bit further in part B. So let's assume that the capacitor that's hiding inside that device is just a parallel plate capacitor, right? Two plates separated by some material. We're going to assume that the gap in between the plates is empty of all material. It's a, I'm sorry Darcy I'm ignoring you. I was just asking, why would you want to put in Nano Farads? Just to show that you know, you can do that. Part of the reason for that is that capacitors if you had to buy one are sold in Nano Micro Mill Leapico Farads. So if you needed to go out really quickly and replace the capacitor in here, it might be helpful to rewrite it in like Nano Farads. So you can go to the store and say, yeah, I need one roughly 60 Nano Farad capacitor for a portable defibrillator please and they'll probably look you and go, I'm not selling you that, you shouldn't be fixing that probably unless you're like a licensed technician so but you could, you know, go to fries or Micro Center and you can buy capacitors off the shelf. They have them, okay? And that's really not a very, doesn't sound like a very big one. You know, we used to be able to go to Radio Shack when those were more abundant and get Pico Farad capacitors no problem, so. Alright, so let's assume that there's a parallel plate capacitor lurking inside this nice plastic box here and since it has to fit in the box what we want to do is say, okay look we know that the area of the plates is constrained if it's going to be a parallel plate capacitor.  More stuff has to fit in there than just the capacitor. So we're going to, you know, take a parallel plate capacitor, so I'm going to simplify the cartoon of this by just drawing two lines like this. So, in fact, this is the symbol for a capacitor. A capacitor in a circuit, and we'll play more with circuit diagrams later, is just looks like a couple of T's that are mirroring each other, okay? Those are the plates and those are the wires that you could connect to something else, like a battery or whatever, resistors, something like that to make up a circuit that does something. Okay, so we have plates that are not square in shape. They are 50 centimeters by 10 centimeters. So I turn the plate to the side. That's what it would look like, roughly, right? Exaggerate it again the sizes here, alright? We want to figure out what gap is needed to make this capacitor do what we want it to do. That is B, 63 nanofarads in capacitance with plate areas of 50 times 10 centimeters squared or 500 centimeters squared, okay? So we know the plate area that's just 50 centimeters times 10 centimeters is 500 centimeters squared, okay? And we can convert that in anticipation of needing things to be in meters, kilograms, and seconds into meters, kilograms into meters. So 500 times 1 times 10 to the minus 2 meters all squared which is 500 times 10 to the minus 4 meters squared, okay? So we get 5 times 10 to the minus 2 meters squared for the area. 5 times 10 to the minus 2 meters squared, alright? So it should be a tiny fraction of a meter squared because that's not that big. Okay? Alright, great. So we have the area. We have the capacitance. We're told there's nothing but air or nothing but empty space inside this thing. And so if we write down the capacitance of a parallel plate capacitor, it's epsilon naught, a constant of nature, times A over D. We want D. We have A. We have C. We can rearrange. So D is going to be equal to epsilon naught A over C. Okay? And we can plug in all the numbers we have and you should get 7 microns. That's the gap that you'd have to have between these plates. So, you know, sort of roughly this scale, 7 microns in between them. So certainly matches our requirement for the archetypal parallel plate capacitor. The area, the length of any side, is certainly far larger than the gap between the two plates. Is this feasible? Do you think you can engineer something like this with a 7 micron gap that's filled with empty space in between, let's say, two copper plates or something like that? Well, does anybody know? Can anyone give me a scale? How do I compare 7 micrometers to something? Okay, yeah, so human hair, right? That's a teeny tiny thickness. Do you know how thick human hair is? I think it's a diamond. I'm undershooting it a little bit. 200 microns is the thickness of a human hair. Okay? Would it be hard to keep two metal plates separated perfectly in a device that has to come off the wall and work like that if you have to separate those plates at less than the thickness, almost 100 times than the thickness of a human hair? Lucy, are you exploring human hair right now? Okay. Yeah, that's tough, right? Maybe we're just lacking imagination.  But the good news is that nature has made it possible to engineer something that size that doesn't require sort of crazy engineering feats like this. Just to give you an example, the smallest working electronic device that we can make like state-of-the-art charged particle tracking systems for leading edge particle physics experiments that I work on. They have silicon micro strip sizes that can be read out that are of order a micron or slightly smaller than a micron. And that technology is like one of a kind, really expensive. You're not going to roll this off a factory floor kind of stuff. It's not going to be in the camera and your iPhone yet. I say yet because one day it probably will be. All right. So that's pretty tough to engineer. But the good news is we know from looking at the capacitor equation that it's actually possible here this is the permittivity. This is a constant. It has a name. And it's known as the permittivity of free space. So let me skip ahead here. Empty space has nothing in it. No atoms, no electrons. For all our purposes there's really nothing there at all. No substance, no matter. But it's possible of course to shove a material in between the plates. And when you do that you're shoving dipoles in and that will weaken any electric field that's present between the plates. And it will allow you to store more charge for a different geometry. So by shoving a dielectric into this material we can actually space the plates out a little bit and still get our target to meet as well. I should note, does this look like a parallel plate capacitor to you? Can you conceive of this being the right shape for something that's just two rectangles separated by a gap? Is this how you would design it if you were going to make a capacitor container for two plates separated by a gap? What shape would you make it? A rectangular. It would be rectangular, not round like a cylinder. Actually this kind of is a parallel plate capacitor but it's a cheap. What you do to make I can demonstrate it with these actually. So here are my parallel plates and I don't want to ruin any of your quizzes here. I'll take one of the quizzes. So here's my dielectric. I want one of the quizzes. I've made a parallel plate capacitor so we imagine that the quiz is made of some non-conductive material that's scary. This is big. I have to make a big case for this but I could maintain the parallelness of the plates while saving volume or saving area at least. Any idea how to do that? See? What's that? Roll it. That's no accident but that's cylinder shaped. So it's actually a new conductive plate separated by a dielectric material that's been rolled into a cylinder and that's why this thing is round. That's why this thing is shaped like a cylinder. So that's how you can make a round parallel plate capacitor a circular parallel plate capacitor. At any point if you look at the plates real close there's just a uniform gap between them it's just that gap, the plates, walls bend as you go. So that does introduce extra little realistic effects into the problem that you have to think about advanced physics and engineering is for. Okay? Alright, so let's sit here. Something fundamental. So if I go out into the middle of interstellar space as far as I can possibly get from planets and stars and asteroids and comets and gas and dust and all the stuff that sort of surrounds us in space in a solar system go really far away and just find a square meter space that has absolutely nothing in it. What I know from the laws of physics and also from just doing an experiment is that if I evacuate that space entirely and if I put a bunch of positive charge over to one side of it and a bunch of negative charge over to the other side of it I will make an electric field through that empty space. Electric fields do not require so far as we can tell a medium to propagate. And that will be an important thing later in the course. So in effect this number right here this number right here tells us about how empty space permits electric fields to pass through it. And that is what makes this the fundamental constant that we have to worry about. This epsilon naught. Okay, so epsilon n a u g h t epsilon naught. Okay, epsilon subscript zero. That actually tells us something very deep about the universe and all from just constructing capacitor systems because it tells us how the vacuum of empty space allows electric fields to move through it. Now we can change empty space by making it not empty anymore. We could put some ceramic inside the capacitor and alter that number.  That's it. So you're taking epsilon naught and you're turning it into some number epsilon which is equal to epsilon naught times the Greek letter kappa. Okay, try that. There we go. Kappa. Kappa is what's known as the dielectric constant and all it does is it scales up the vacuum to some other material. That's it. It takes vacuum and turns it into ceramic. So to add a material to alter this equation it's just that there's shove a number in known as the dielectric constant. So let's look at a more realistic capacitor system. You have one but you have lots of them inside you right now. Every cell in your body is a capacitor because it has a membrane that does not freely allow charge to penetrate it unless those charges are intentionally pumped into or out of the cell. The pumps can create charge imbalances between the sides of the membrane and that creates a voltage. So this bilipid membrane here is a dielectric medium with charge separated on either side say positive sodium ions over here and then negative 4E anions over here okay. There's an electric field weakened by the dielectric constant of the cell wall but nonetheless this is effectively a capacitor. That's all this is. It's charge separated by a distance that it can't cross. Okay, so that lipid bilayer is clearly not vacuum. It's not empty space. And so one has to modify the vacuum constant epsilon not by some number kappa.  Okay, kappa for the cell membrane is about 3. It's about 3. And it's a dimensionless number. It just multiplies epsilon not. So epsilon not has units. Kappa just multiplies it to scale it up to be a material instead of empty space. Alright, let's go to the problem. So here's the picture of the cell membrane again. The membrane thickness of a biological cell specifically I believe was blood cells was measured for the very first time in human history using capacitance. It was not observed by the naked eye. There's a reason for that. You'll see in a moment. The first way in which the cell membrane size was determined was using capacitance and electrical properties of media. So let's say that we have an experiment that determines that this electric potential difference between the inside and outside of the cell is 70 millivolts. And that number ought to look familiar to people that have studied cell biology. The experiment also finds that to maintain this potential difference the cell has to move 0.17 picocoulombs of charge specifically sodium from inside to outside. So it pumps sodium out, builds up a charge imbalance inside and outside and gets to about 70 millivolts potential difference. So what's the capacitance of the cell membrane? That's your first question. What's C for the cell membrane? Second, cells themselves can be seen with microscopes. You guys have looked through microscopes and looked at cells before. Plant cells are really easy to see. Our biological cells have a radius of about 5 microns. So just slightly larger than the gap that was needed in between my parallel plate capacitors for the defibrillator. That's crazy small. So cells have a radius of about 5 microns. What's the thickness of the cell membrane? So here's your hint. Treat the cell as a parallel plate capacitor whose area is that of the sphere. So here's a model of a biological cell. It's a sphere with an inner sphere and the thickness in between is the cell membrane. So that's the dielectric and if you zoom in on any little piece of this bent surface you'll see what looks like a parallel plate capacitor. It's just that it bends very slowly on the scale of this picture right here. So this is a very simple grossly oversimplified model of a cell but nonetheless you'll find that this is a very effective model. So you can pretend that we've taken a parallel plate capacitor and instead of rolling it up like this we've kind of turned it into a sphere. So we've kind of rolled this thing up so it's a perfect sphere. So go ahead and treat this thing like a parallel plate capacitor where the area of the plates is equal to the surface area of a sphere with the radius that's given there. So calculate the thickness of the cell membrane. So yeah, Shannon.


So team keep it clean. Hey, I hope y'all feeling good right now because we got a lot of great stuff to talk about when it comes to These Baltimore Ravens, but before we get into it. I gotta say I appreciate y'all make sure y'all subscribe to the channel Let's keep on growing and leave a like on the video because that helps out the channel That helps up helps out all the YouTube behind the scenes stuff a whole lot more than you realize Trust me. So I appreciate the fact that y'all have been doing that a lot more So thank you for that now with Baltimore Ravens Marlon Humphrey. He had been in my aid for the past couple of games We know he he left I forgot which game it was that he left earlier seemed like it was so long ago But Marlon Humphrey been gone for a while, but he started practicing ahead of the Chargers game But they did not play him in the Chargers game. We were like, okay, cool. No problem. It's fine But I was worried. I remember going into that charges game with Marlon Humphrey not playing I'm like Justin Herbert. He likes to throw it all over the place So I was scared about that one But he didn't play and it worked out just fine the Baltimore Ravens still won and that gave Marlon Humphrey even more Time to rest but now this week the bye week's over baby. The bye week is over. We had a lot of fun doing the bye week I'm sure a lot of Ravens fans took little vacations here and then what not and y'all are chilling y'all relaxing like oh We ain't got a stress about them rave this week and it was great But we back now and but so is Marlon Humphrey Marlon Humphrey returned to practice and he said hey, I'm feeling good I'm feeling great. I'm ready to play. So Marlon Humphrey We will need you against Puka nuca against Cooper Cup against them Rams because they gonna bring it They gonna bring it. They feeling real good right now. Every time they had Puka nuca and Cooper Cup in line up. They three you know, they three know what both of them in the line up So Marlon can help the Ravens make that three in one. Hopefully. Let's see what happens Sunday But anyway, I'm at a big a not a big a who left the last game and he had like concussion like symptoms and whatnot He was practicing as well. He was limited as a participant But he was practicing the fact that he is practicing so early in the week That is a great sign for the game coming up this week against the Rams and Justin Madi BK's availability because I'm sure Justin Madi BK is gonna want to show his his mentor mr. Aaron Donald like hey, you don't talk me some stuff and I'm I learned that stuff and I'm showing that I can do that stuff now I'm coming for you Aaron Donald say Justin Madi BK you on your way, baby You are on your way now you on your way to get paid for sure But maybe if you continue this you could be on your way to being one of the best interior defensive linemen in the league Keep it up, baby. Anyway continuing Trent Simpson who had missed the last couple of games with concussion He returned to practice as what so look like the Ravens are getting all these guys back in practice That's a beautiful thing, but he returned a practice So that was really really nice to hear about and Malik Harrison who the Baltimore Ravens They designated him to return. He was also practicing as well So again Ravens like remember when Lamar said hey, we don't want to peak too early He was talking about the plan on a football field But this I'm gonna apply to not peeking too early to the injuries into the health They don't want to be too healthy too early So Ravens are still they getting all these guys back still and hey, it's gonna get a little bit It's gonna get even better a little bit later. We're gonna get into it a little bit though Now John Hall ball. He said he just John Hall ball said is like he had to bring this up He had to talk about it, but he did he said that he isn't planning on our Darius Washington returning this year, but He's not a hundred percent sure yet. Now. That's crazy That's crazy. Like I wrote our Darius Washington off I thought he was done for the year for sure and the whole ball is not saying that he's necessarily coming back But I remember they had not given us anything with our Darius Washington for sure They had not said that he's done for the year He did have surgery early this year, but they had not officially said oh no our Darius Washington is done for the year Every time they talked about our Darius Washington. They said that he had the surgery And he would be out for a while, but they did not say that he would be out for the year So just a matter like think about this Pepe Williams. He was practicing too Remember he was out from since the beginning of the year So Ravens are getting a lot of people back in a secondary man and for a second there has been playing pretty good to be even help Everything lining up.  He did not practice And I was thinking oh is it his back again, but they said it was just an illness So maybe he went away on a bi-week or something I don't know where he was that maybe got a little sick or whatnot, but it's okay because I would expect all there I'm tripping. I'm saying all this watch. I was expecting Richard Bateman to be back in the building tomorrow I don't know nobody though. That's just me. That's just a hunch. That's it But if you got an illness let him get some emergency or some let him take some some some black seed oil or something like that Maybe some Seymour's what whatever Get well soon Richard Bateman And we still waiting on Russia Richard Bateman to really have that that breakout Because we've seen him make some nice plays here and there, but just we still waiting on that breakout game I did see somebody said that um, I forgot the Twitter handle I wish I could remember it right now, but somebody said I'm not they tweeted this back in October They said I ain't tweeting again until Richard Bateman get a honey yard game They ain't tweeted since so it's time for shot Bateman Lamar Jackson top monkey It's time to let my guy tweet again. Please bring his account back now Lamar Jackson He had made a statement in a presser where he talked about and I really appreciated He said he talked about how every game it felt like a playoff game and I mean, obviously not playoff time yet But I mean it kind of is and it's best to really start getting ready and getting prepared In for the playoffs because they're right around a corner like literally right around a corner Something that I was thinking about too The Ravens are gonna be playing the Jaguars We'll see what happens with them with everything depends on travel Lawrence But they're gonna be playing the Dolphins and and then the Steelers too So I was thinking like Ravens could end up playing One maybe some of these teams again in the future now My hope is that the because the Ravens are gonna play the 49ers on December 25th money night football the world will be watching That could also be a potential rematch in the playoffs and y'all know how that would be a potential rematch in a playoff So Ravens like it you got to be ready man Stay ready so you ain't got to get ready And if you got to play a team again for the second time then that means you would need to be extra and over prepared But it ain't all such things being over prepared. So we'll see how that thing shakes out now speaking of the 49ers Remember that guy Zach Erts and been pretty quiet on Zach Erts So I guess he's been sitting back waiting and watching. I think he really just wanted to see the Ravens play That's what I think I think Zach Erts just like you know what I'm gonna chill for a little minute I want to see what these Ravens look like cuz I ain't seen them in a while They want to buy a week when I got released and whatnot. I want to see how they looking cuz he saw how Philly was looking He's like I don't think I want to go back to him and but now They said that the 49ers 49ers are interested in Zach Erts and one thing I really respect and am I about the 49ers is that they have been a strong team for Years, but they continue. They always looking for ways to get even stronger. They just added chase young They always adding people they always trying to get even better and I love that about the 49ers They do not stop no matter what um, so we'll see what happens with Zach Erts We haven't heard of him making any visits to anybody yet going anywhere yet Now one thing that was interesting and I don't know if y'all caught this too John hardball was had a presser. I think it was on Monday. He had a presser and in that presser They asked about his that I mean the Baltimore Ravens interest in Zach Erts and John hardball said the famous saying we like our guys We like our guys and when he said that I was like Zach Erts must be at BWI right now because we know we don't heard the Ravens say we like our guys before and we know You know what happens when they say we like our guys They still end up adding another guy at whatever position they talk about. I remember the most recent Well, maybe not even the most recent but one of the biggest times We heard that was a couple years ago when it came to the wire receivers They say we like our guys we're insulted that you all think we should add a receiver We're insulted. We like our guys what they do Drafted receiving the first round And he's not one of free agency to so anytime Ravens say we like our guys They don't like that guys, but you get what I'm saying, man. Now Something that It'll seem like it was a little bit of petty from the Ravens, but I know it wasn't petty It was more so respect. Oh, they'll back on Junior. He will be a captain This week against the Rams his former team and all the back of Junior talked about he said he ain't got nothing But love for the Rams and of course, I mean he helped them win a Super Bowl He unfortunately went out in that game, but he helped on the Super Bowl So he was a big part of that But he will be a captain against his team So hopefully he'll be a captain in a big-time playmaker too because Baltimore Ravens could use it This will be a nice game because you know Ravens like I know I know y'all know already Like Ravens when it comes to significant players on their team when they play against their former teams Ravens Like trying to make these players show out. They look they love doing it Like when a player that used to play when Ravens go up against the team a player used to play for the Ravens They try their best to help that player show out So I would expect Odell Beckham, Jr. If you were fantasy person, I would start Odell Beckham Start I might put them in a flex or something like that But I think that this could be a big game for Odell Beckham, Jr. Not because this is just an emotional game either. No, but I really think the Ravens they gonna try like heavy But we'll see Also little bonus to Pro Bowl voting, but okay We ain't worried about no Pro Bowl like get Ravens players get the votes But we got other bowls to take care about to take care of excuse me Kevin Zitler He's the leading vote getter against amongst the guards in AFC Roquan Smith He's the leader in the inside lineback and Kyle Hamilton and Geno Stone Data leaders at the safety position at strong safety position. So that's a beautiful thing to see So she's for Geno Stone and for God Hamilton being a second-year player Geno Stone being one of the lesson-owned players, but for them to be leading in Pro Bowl vote That says a lot that says a whole lot and I love that and I love that they're getting the recognition that both of them Certainly deserve so that's amazing to see and then the Ravens will be wearing purple on purple This week against those Rams so a little fashion update for anybody that might be going to the game Well, even if you're not going to the game You just want to dress like the Ravens wear your purple jersey and wear some purple pants too And then you could fit right in like the rest of the Baltimore Ravens team keeping clean I love y'all so much. I really do Make sure you subscribe to the channel again. Let's keep this thing moving. We've been having a very fun season And we still got a little bit of season left Then we got them playoffs then the Super Bowl right around the corner And we will be with you every single step of the way team keep it clean. I appreciate and love y'all so much We out


First off, congratulations on the win. After being down by as many as 18 points in that first half, how are you guys able to turn things around in the second half and get the win? We talked to halftime. We just had to come out and fight. We knew we could take this game from them. They didn't want it as much as we did. So we came out, we fought. And Joe kept saying, get three stops when we back in the game. And that's what we did. Total team effort. How satisfying is a win like this to bounce back after a two-game losing skit and get in the win column? It's definitely huge, man. We needed this one. And we're going to push forward into the next game tomorrow and play the same energy. I've talked to you a lot about your defense. You had 16 points tonight, three straight buckets in crunch time in the fourth quarter. How much fun were you having out there and being able to contribute and execute? That's all it is, man.  We practiced everything yesterday. So we was ready. I was ready. And they let me score them.  And I made buckets tonight. And what's it like bouncing off of Kevin Durant, who had another big game, a near triple double and 34 points tonight? That man is different. Different. The way he scored a ball, the way he played a game, he gets everybody easy touches, easy buckets, man. He's different. Thanks so much for your time, Bruce. We'll see you tomorrow night. Thank you.


I think that's how we all started, right? Absolutely. All the industry events and going to every meeting where they gave out information and pamphlets. I mean, we all kind of start the same way, the same way from the bottom with no contracts. With no contracts, no anything. No anything, right? Yes, yes. That's great to hear that. Exactly. But as you continue to do that, you realize, okay, I have to hone in my energy here. Because if I'm spending all my time at all the events, when am I actually building the business and working for the business instead of working in the business? And so then you have to really get strategic to say, okay, how do I streamline this? Instead of me going to nine, 12 different events, what are the top three events that really focus on my capabilities where I need to be at that, that really honestly is selling what, buying what I'm selling rather, and you hear that and I can tell you that used to irritate me.  But it honestly is true because if I'm spending my time over here at USAID, and they're not really trying to, everybody's buying IT, but you know what I mean, let's say they're not small business friendly and I'm not saying that about USAID. I'm just using them as an example. I need to as a woman owned small business with the A-day certification at this point, I need to be with agencies that are utilizing those versus agencies now that have mandates that say, we have to use GWACs first. You have to know those little tidbits so that you don't end up spending and expending your time, which time is money, because you've got to charge that time somewhere. At least I did, because again, the benefit of being a part of a large company is when I set my company up, I kind of model after the large company.  So allocate it to the things that's going to move the needle on your business.


What's going on everyone Sam here with late in sports cards. We are ripping. Well, first of all happy release day We're ripping 22 Panini playbook football hobby 8 box half case break number one pick your team style Let's read off a list of our names and our teams Erin L with the Rams Armando B Chargers Charles K football team Chris C Dolphins David R Ravens Broncos Seahawks Edward P with the Cowboys Hano B Raiders Hunter H chiefs Jacob H with the Giants Jeff M Bears Colts Niners Jordan B with the Texans Long J Panthers Matt G Cardinals Matthias S Browns and Patriots Nicholas T Saints Patrick G. Bills Paul O with the Packers Richard O. Bangles Shakila B with the Steelers Falcons Jags Eagles and Bucks Steven W Lions Todd D with the Jets and Titans and Tony K with the Vikings. Good luck here, everybody Let's do it. See what we've got in here Four autographs or memorabilia cards per box on average So I guess with the booklets just make like a separate stack for the recap and then just When you put them into the thing just tape it so you could see the team logo for sorting and shipping and I could show like Recap and everything, you know All right starting off Jamar Chase That is 16 out of 25 yearbook. These Cards are look really good this year actually they're like at like kind of like acetate on top two color patch with the bangles Like that they seem like they're better quality than in past years That's gonna be a Brian Robinson jr. 13 of 25 nexus dual one color two color patch for the commanders Yeah, these actually look really good the feel like the stock of this card. It's fantastic We've got goal line graphs is gonna be a Michael Carter for the jet 16 out of 199 Hey, let's look this looks great, man I'm bought in and the first booklet rookie playbook Jersey autos Brian Robinson jr. Three colored Patch auto that is on card For the commanders. Yes, correct Matt correct Yeah, there's some super short prints in here, but no technical case hit Nice. This is this is in my opinion so far the best that playbook may have ever looked since like the early 20 tons This is great. This is actually really good four five six down to again guys nine to go nine to go on number four Pretty solid start right there The show for show a mammoth material is son Haskins that is 74 out of 199 for the Titans the son Haskins We've got cool one here is gonna be a hash mark saw to 15 of 99 Mike I'll stop for the bucks Mike I'll stop for the buccaneers hash mark signatures Love how it has the position and the number down on the bottom Up next is gonna be a rookie auto Bailey zappy That's gonna be base Base auto. I don't believe that is numbered nice one there could recap it is And we've got the armory booklet.  So we got patch football helmet patch patch and glove Congrats on that one there Falcons that looks good, dude. Yeah, and that is gonna be Desmond Ritter 40 of 49 on the armory booklet Very cool looking this year. Yeah, dude. They have so much they can do on these designs and they always look great box three Got dynasty ripping later on too. We got two cases in the morning shift with myself And here that is gonna be a George Pickens nexus uh 61 of 99 jersey patch for the Steelers A lot of patches coming out of this today so far too, which is always good Grats on that Pittsburgh. We've got a Saquon Barkley that is 19 of 25 For the Giants on the yearbook jersey Grats G men Followed by first auto is gonna be Sam Williams uh for the Cowboys Sam Williams Cowboys and then we've got 11 of 25 That is Isaiah Spiller three color patch green rookie booklet. It's a full-sig Isaiah Spiller as well They put in a new booklet this year. It's called storybook.  Good for him, man We applaud you out. It's gonna be a mammoth material of George Pickens. This is one of the the classic playbook Uh sets right here the mammoth materials very nice We've got that is another mammoth material this time a patch is going to be 11 of 75 Jamo for the lions Jamison Williams Bear's gone in five. Thank you, Robert Jag's gone Dolphin's gone in four Packers gone in eight A lot of spots coming in. Thank you everybody Got Calvin Austin on the rookie auto Base rookie auto for the uh Steelers That's Pittsburgh And rookie playbook Jersey auto is going to be a taekwant Thornton Nice one there 150 out of 299 taekwant Thornton. All right. Grats there patrons The is signature you have the teat the taekwant Thornton the TT Classic taekwant Thornton classic taekwant There's a J. Fields 27 of 49 and these jersey cards these yearbook jersey cards are awesome Three color patch. We've got tight end university George Kittle sunday's best 72 out of 99 for the Niners Sunday's best Next up for the Colts is going to be Jelani Woods base rookie auto Jelani Woods For the Indianapolis Colts one of the last teams taken and then we've got a rookie playbook Jersey auto. There's Calvin Austin Everybody's talking about Calvin Austin. There you go. You have the stock of the When you guys get these these cards in anybody who bought into the break definitely Take them out of the top loader and just kind of see how they feel. It is awesome 20 of each of their rookies. There you go Happen because like some of the some of the bigger names will be a little bit shorter printed Like they'll just be harder to hit. It's gonna be dope, dude.  That's really sick Grats on that sin see that is sweet, man. Even as a ravens fans. I got a fan. I gotta appreciate that That's sweet. That is a chunky patch Uh, johan dotson. That is 11 out of 49 For the you said it's purdy in this. I don't think no no purdy in this unfortunately Johan dotson We've got a herman more hash marks one of 49. Wow, look at the The foiling on this one too. It's like an acetate. Yeah, it's like an acetate on it All of those the yearbooks and then whatever that the nexus I believe that is right Take a look at this for the jags nine of 99 fred taylor Three colored jersey or patch auto for the jags, dude When's the last time we've seen like fred taylor on on card product, dude Jags all-time leading rusher. This is a vaughn card right here. That's a vaughn card. If I've ever seen one That's sweet, dude. That is so sweet Love me some fred taylor fred taylor. I think leads the nfl all-time in rushing yards a player not in the hall of fame I believe that's true It's good man. It's looking good this year so far. I'm I'm very in on this I'm very in on this We got another jamar chaser basically going for this this rainbow at this point that is 32 of 49 Gator legend. Oh, yeah We've got a triple team trio is matt stafford cooper cup and erin donald That is 43 of 99 for the rams Raven seahawks gone in four and five Appreciate you. Let me drop you a link really quick one more time on number four Three four five six down to seven to go everybody some good teams still remaining seven at sugo Cedric wilson jr. Hashmark signature that is 55 of 99 for the dolphins god of foiling on this is sick this year too That's the first year they did this Herman more. Yeah, you said uva legend, right? Virginia cavalier herman more and 299 for the raiders.  It's got the uh, nfl 100 shield on it too Granted it is mark ingram who played there for basically one year, but Still dude color rush jersey for 30 bucks All in dude. Nice. Here we go. We got him a homes 86 out of 99 three color two color Loving the checklist in this so far too Nice one there patch my homes for the chief scratch chiefs We've got a stephan digs hot routes at his 29 out of 75 We got to pull one of the down and dirties the game use Yeah, they're booklets Yeah, he's all right patch my homes is okay kind of a bum We've got uh sam williams that is going to be base rookie auto for the cowboys They're they're I mean we have six cases this this morning.  There we go ravens. Congrats on that Uh, no, who is it manny? solace Let's do a quick recap.  That's that nuts Very happy on that one Uh sam williams There's cedric wilson herman more. Uh, yeah a term and more Jelani woods, uh, calvin austin sam williams bailey zappie Mike ousa and goal line grabs. These are sick too There's always they're only running backs and they're like like full size horizontal of like a goal line score That was michael carter for the jets booklets. We had kyle hamilton for the ravens We had zamir white for the raiders Fred taylor for the jags. That's awesome, dude calvin austin for the steelers a Tyquan thorton for the patriots Some of the numbered ones we had to 25 isaas spiller for the chargers We had an armory booklet to 49 for the falcon desmond ridder and then a brian robinson jr for the commanders That is going to do it for the break everybody. Thanks again for getting this builds up. I do appreciate it up next number two


Today's topic is property, plant, and equipment. This is IS-16 and in fact it's a very old one, but it's so important that in every business you will come across with these plant, equipment, property, etc. So that's why we need a proper accounting treatment of these plant and equipment. First of all, learning outcome. Students will be able to understand what constitute property, plant, and equipment. Per the prescribed format specified by the IS-16, they will record property, plant, and equipment related transactions correctly at the time purchases and sale of such assets. Learn how to present and disclose property, plant, and equipment in the financial statements. So it's not only in the balance sheet. It affects income statement. It also affects cash flow statement as well. Now property and plant and equipment involve a large amount of investment. A large amount of cash is invested in these assets. They are acquired for use in operation and not for resale. It's a very important thing. They are not for sale. They are not like inventory. They are supposed to be used for production or for even rendering services. They are long-term in nature and usually depreciated. They possess physical substance. You can kick them actually and then they are property, plant, and equipment. Purchase price includes import duties, non-refundable taxes, purchase taxes, less trade discount, and rebates. Do you remember they are deducted from the cost of the plant and property equipment? But if there are some rebates or rather you have some provision that when you make payments, you pay less. So that discount is not in fact taken into account. That is only the discount at the start of the equipment. Cost contributed to bring the assets to the location and condition. Whatever amount you spend to bring it to the condition and location. Necessary for it to be used in manner intended by the company. In fact, you are buying an asset for a certain purpose. Still such time that asset is start giving you the intended output, all expenses to be added to the cost. Then spread the cost over its estimated useful life, which is depreciation. In fact, we are using these assets and continuously they are reducing their value also. Because if you use something, obviously there is a reduction in its value. Cash paid on acquisition shown in cash flow statement, assets reported in a balance sheet, and depreciation reported in the income statement. As I said earlier, this affects all those three important statements. I-16 deals with the issue by being clear that an item of property plant equipment should be recognized as an asset. If only if it is probable that the future economic benefits associated with the assets will flow to the entity and the cost of the item can be measured reliably. Because that is also very important that how the cost is measured in a particular asset. Property plant equipment are tangible assets. As I said, they are intangible assets also, but this is a tangible. Are held for use in production or supply of goods and services for rental or to others for administrative purposes also. So these are the three main purpose of plant equipment. Are expected to be used during more than one accounting year. It will be a long term asset basically. It can be used for four year, five year depending upon the type of assets and its useful life. Depreciation basically is the systematic allocation of depreciable amount or cost less residual value of an asset over its economic useful life. Now do remember here, even the depreciation we estimate a rate. Similarly, the residual value, the solvage value when the asset is expired its life. You still get some amount out of it. So we have to make an estimate about the life and about the residual value. And then we calculate the depreciation because cost minus residual value is the depreciable value of an asset. And that will be allocated systematically. That's important. It's not that you can do and then charge any amount to the profit and loss account in any year. No, there should be some systematic methods to be charged to the income statement. Method of depreciation. Look, there are straight line method. Usually this is all over. People charge regularly that if an asset is of let's say five years. So each year same amount of depreciation they charge to the income statement and the accumulated depreciation is credited. Reducing balance method or some of your digit method. Now this is again an important one. You have to be very careful that what the examiner method is suggesting while working a question. Reducing balance method means that you reduce first year depreciation and what is the net book value after that first year depreciation. Then you take the depreciation of the net book value. I mean every year you start reducing the accumulated depreciation and then you keep charging the depreciation on that asset. Now what happened normally? Sometimes we use some of your digit method that if let's say it's five years. So what we do we add five, four, three, two, one and that comes to 15. So the first year depreciation will be five over 15 and the last year will be one over 15. So you can see the difference and the beginning we are charging a high amount of depreciation and towards the end we are charging a low amount of depreciation. And the reason being the new assets is depreciated more but the repair and maintenance is less. But as the assets keep running and using then the depreciation is reducing but the repair and maintenance is increasing. That's why reducing balance method is used. Then activity method, R's unit of output. That is also, you know there are certain assets which work on a certain number of hours after certain number of units you produce and you use those numbers, estimated numbers of the whole year, I mean the whole life of that asset and you work out the depreciation per unit or per hour. And accordingly hours served in a particular year multiply and you get the depreciation amount. So here you will see it cannot be a systematic because you never know year one, number of units are different, year two, number of units are different. That's why it's not a systematic distribution. Then there is a composite method. This is something new in the sense that if you have an asset which is a big one and the number of item attached to that. For example, take the case of airplane. You have engines, you have interior and you have exterior. So now question arise how you charge depreciation on an airplane. So what we do? We divide these three parts because the life of engine is based on flying hours. Life of interior again is shorter because people use those seats and the damage damage them. Outline mean outsider, mean the out. That will be a slightly more but still sometimes we do re-innovation of the outer part of it as well. But that is again not increasing the value or the life of the assets. Now residual value is the estimated amount that an entity would currently obtain from the disposal of an assets after deducting the estimated cost of disposal. Obviously it is an estimated figure because you never know that when the asset is used up you might get more than what you have estimated earlier. Then cost method carrying amount. This another important thing we should use the word carrying amount, not the carrying value. Carrying amount is the amount at which an asset is recognized after deducting any accumulated depreciation and accumulated impairment losses. Depreciation is okay but so far impairment loss is concerned. That will be covered in the next topic, impairment of assets. Fair value method. So sometimes we also look into that assets will be reported in the balance sheet income statement on the basis of fair value. And again it is an independent standard on it. So we will discuss it separately that how the fair value of certain assets are determined. The buyer and seller act in their best interest. Thank you very much.