Now I want to talk about the divisions of philosophy. And so let's begin with the term philosophy, which is a compound of two Greek words, Thelos and Sophia. And Thelos means something like being a friend or a lover of something. And Sophia just means wisdom. And so what philosophy is, is who philosophers are, are people who are friends of the wise, or they're people who love wisdom, and they try to cultivate wisdom. Now notice that they are not just selfish. That is, they are not people that claim to be wise. There's a whole other group of people who say, we are the wise people, like the seven sages or this office who say, we've actually got wisdom. Philosophers say, we don't actually have wisdom. We just really like wisdom. In fact, we love wisdom. We have a desire for wisdom, even an erotic desire for wisdom. It's the most important thing to us. We care about it more than we care about riches or power or things like that. We want wisdom instead of those other things. Or we think that wisdom is the key to getting those other things that people think to be good. Now, we can divide philosophy into, we create various divisions of philosophy. And essentially what we do is divide them into different kinds of sciences. So over here, I've given you Aristotle's classical division of philosophy. His major division is between, on the one hand, theoretical philosophy and on the other hand, practical philosophy. So Aristotle invented the distinction between theory and practice. That distinction had not been made prior to him and he made this distinction and made it a distinction within the field of philosophy. Some things are theoretical, other things are practical. Theoretical sciences include theology or the study of the gods, mathematics or the study of mathematical entities, natural science, the study of natural things. Practical science includes things like ethics, economics, and politics. And the definition of these has to do with the ends for the sake of which those sciences are pursued. Theoretical science is pursued for no other reason than or needs to be pursued for no other reason than that it produces knowledge itself. So I can want to learn about God or want to learn about natural things and I don't need to be able to do anything practical with that knowledge. That knowledge just is valuable to have in and of itself according to Aristotle. Whereas practical sciences are undertaken for the sake, we try to acquire those kinds of knowledge for the sake of doing or producing something. So in the case of ethics, let's say that the purpose of ethics is learning how to live well or to be happy or to be virtuous or to get pleasure or something like that. Well, we don't want to just know about what pleasure is. We want to enjoy pleasure. We don't just want to know what happiness is. We actually want to live well. And economics, again, we don't just want to have a general theory about wealth and poverty. We want to have much substance, have a growing economy, have riches and so forth. And politics, we don't want to just have a theory of law and order, we actually want to have a well-ordered society and so forth. So theoretical and practical sciences are undertaken for different reasons. And so they are different kinds of science in his view. Now, technically he recognizes another classification of science. You might either think of it as a subdivision of practical science or on its own called productive science. And that includes all sciences which are undertaken not just for the sake of the knowledge itself and not just for the sake of doing something but for the sake of producing something. For example, architecture, we learn as a science for the sake of producing shelters from weather and intruders. And medicine is a productive science. We pursue it in order to learn how to improve health and reduce disease. And so we can have a technical distinction between practical and productive sciences because practical sciences don't necessarily try to produce anything. They try to change the way, what we do and how we act whereas we in theory have a different classification of things that we make or produce. Yeah. Did Aristotle, did he set theoretical science and practical sciences two different things or is it that practical science is an applied version of theoretical science? Well, they interrelate so there are ethics needs for example to borrow principles from natural science because for example, if we're gonna make an argument that what we should be doing as humans is trying to promote virtue or something that we need to have a theory about human nature and if we're gonna have a theory about human nature we need to study what humans are as natural beings and things like that. So they interrelate but they are not, they are different, they are totally different first of all on the basis of their ends. But they are not just applied, ethics is not just applied theology or something like that. These are actually different domains with different objects and so on. So they are different on every level, every causal aspect of them is different but the most important difference is the ends for the sake of which the knowledge is valuable, is considered valuable. Yeah. Would you say that engineering or industry studies are like belong to productive science? Yeah, we would include those in productive science. That would be sort of like architecture. Go ahead. And the different questions so like in practical science after we have knowledge how do we put them into practice? What's that for? Well for example if we learn by studying ethics that justice requires repaying our debts then we repay our debt and if it requires not stealing then we don't actually take money from our roommates first while they're not looking, I think like that. Now those are very trivial examples of course but we do try to learn things about personal conduct and behavior and managing households and resources and organizing society so that we can do things differently and ultimately so we can live better. Because I learned in a class in comp that comp says that the bridge between the rest of science and practical science is that the only argument or are there also different opinions on that? Well there are different kinds of judgments made according to Aristotle in theoretical science and practical science and there are different standards of accuracy and precision that are required. So in mathematics you have extremely precise requirements and we would expect a precise demonstration of a mathematical proof whereas in ethics when we're talking about how a human should behave in a given situation we cannot give something like a strict mathematical proof. We still make judgments such and such as a good thing or a bad thing or should be pursued or should be fled but we have different standards for how that's proven what kind of evidence is brought to bear on it and so on. And so we can get into details about that later. Now but that's division, I give you as a kind of classical division of philosophy but it's not the standard one that Hellenistic philosophers pursue. They have a kind of simplified scheme where philosophy is divided into three parts. Logic, physics and ethics. And in Greek the relevant terms are logos, physicists and ethos. Now so let's start with logic. The Greek word logos literally means reason. But it also means things like word, argument, ratio, formula, speech. So it means a lot of different things and the field of logic in a way relates to all of these. The easiest way to summarize it is that logic has to do with how we reason. Including how we use language and how all of our different uses of language relate to reasoning, how we get definitions and so forth, how we make inferences, what we would call philosophy of language, linguistics, semantics, syntax, all of this is included within the ancient concept of logic, how we make proofs, what standards we have in different sciences. As I just said we have different standards in theoretical sciences than we do in practical sciences. That's a logical matter according to the ancient classification. What the relationship is between sensation and perception and experience and arts, crafts, techniques, sciences, wisdom, insights, intuition, wisdom and so forth. Also dialectical methods, rhetorical methods, criticism, poetics, all of this can be encompassed under ancient logic. Now, the second division, physics in Greek, the word is physicists. Or do we have any physics majors here? Okay, good, we don't have to worry about any of those kind of people. But because I always trick physicists, because you gotta find somebody you know who's a physicist and ask them what does the word physics mean? Okay, and I have never found a physics major at this great university. They can answer that question. And the answer is that it means nature. What physics is about is nature. First of all, what is nature in general, but before trying to give a definition of that, it includes an examination of, for example, matter, space, time, elements or atoms, motion. The nature of the cosmos is an infinite or finite. If it's finite, then what shape does it have? Is the, what shape does the earth have? The nature of the stars, the sun and the moon, meteorological things like rainfall, clouds, winds, earthquakes, volcanoes, plants and animals. And of course humans in a way are natural things. Since humans are animals, humans are even kinds of plants. So humans are natural things in a way. For most of the Hellenistic schools, the gods are also treated under physics because the gods are considered to be natural entities, not some kind of supernatural entity. And so physics deals with all of those kinds of, all of those kinds of topics. The last topic, ethics, Greek word is ethos, which means something like character. And it's related to a term that means habit. And ethics really has to do with your personal character and your personal habits. But it's in general a theory of personal conduct, virtues and excellences like temperance, self-control, courage, wisdom, piety. I think I'm missing a couple. But also things like how you relate to your family, how you manage a household, how you manage resources in general. So economics, leadership, politics, constitutional, constitution building and framing, legislation, judicial judgment. And in general, happiness, prosperity and success. Trying to come up with a theory about what those things are and how we can attain them. What the purpose of human life is, what the meaning of living is, why we should, first of all, whether we should go on trying to live and then if so, why, those kinds of questions. So all of the schools of Hellenistic philosophy have views in each of these domains. And the Hellenistic philosophical school is an institution that has got well-developed theories in each one of these domains. Okay, so any questions about that generally before I start giving an overview of what their positions are in each of these domains? Yeah? So in order to fall on your logic or ethics? Ethics, basically. But again, as in the case of the interpenetration of theoretical and practical science for Aristotle, there is a logical aspect of ethics. So of emotion. And there's also, by the way, a physical aspect of emotion. Okay, so suppose I was to define anger as boiling of blood in the region of the heart as Aristotle does, or as firing of C4 fibers in some hemisphere of the brain, as we might do now. That would be like a physical definition of anger, a very reductionist or a limitist one. But there is a physical component to anger, right? And this is clear because it affects our bodies and you might turn red and it might make your heart race and things like that. So there's a physical aspect to it. But there's also a kind of cognitive aspect to it. So suppose we define anger as a burning desire to repay pain for a perceived slight or something like that. That also happens to be Aristotle's other definition of anger. Okay, well, that's a kind of cognitive logical definition of anger, of a sort of thought process that corresponds to being angry. And it's a definition. And so what is a definition and what are the standards of definition and how do we come up with those? And why isn't the physical definition enough? Why do we also need this cognitive definition? Or can we get rid of the cognitive definition and just focus on the physical part? We can get rid of the physical part and that's really irrelevant. We focus on the cognitive part. So this is not meant to say that these are isolated spheres. In fact, they all constantly interpenetrate into one thing.  So they say things like, well, logic is the stone walls around a garden and physics are the plants and the trees that are growing within it and ethics are the fruits on those trees. Or again, they say that logic are the bones and sinews of the animal while physics is the overall operation of these parts and ethics is the soul of it. And another one that I can't quite figure out why they say this, they compare it to an egg where logic is the outer shell of the egg and physics is the white part of it and ethics is the yolk. Somebody could do that for a research paper trying to figure out what the hell that analogy means. I don't know, but the point of these is that they all interrelate. But there is a question as to what order they should be studied in and there's a big debate as it were a metaphilosophical debate about which one should we study first. So some people think, well, we should study logic first because if the people can't reason and understand what definitions are and so forth then they're not gonna be able to learn anything else about philosophy. But physics oriented people will say we need to study physics first because if we don't know what reality is then we wouldn't be able to figure out how we can reason about it. And then other people say, no, you got to teach ethics first because if these people don't have ethics you shouldn't even let them out of the classroom onto the streets, you know.  And so there's different positions on how those should be studied and in what order and what is necessary to understand the other things and there were developed pedagogies that attempted to present the schools in various ways. The Stoics had defenders of all three, all permutations of what order they should be studying today. Yeah. Could you just repeat what ethos means? Well, it technically means character or habit really.   Those are those kind of things, yeah. So the Stoics had proponents of all three, what about the other schools? Well, all schools have proponents of all three. I mean these are just, you need to have some position on each of those to be a school really. You need some concept of reality, some idea about how we reason about it and then some views about the end for humans. It's just that with the Epicureans, the view laid out by the founder of the school Epicurus was not really modified. They thought, yes, that's the order that it should be studied in, essentially logic, physics and ethics. And but they have a totally different pedagogical theory about how people learn and how instruction works and what kinds of texts should be written to support that. So really they have a totally different view about education and that's why, and so they still, there's still a lot of developments within the school but they don't, there aren't internal disputes about the order. So I mean card carrying Stoics will have honest to goodness disputes about which of these should be studied and in what order, yeah. So is the difference between logic and physics, I know this is much later, but it's kind of like the difference between the rationalists and the empiricists? No, the difference is that one studies reason and the other studies nature and those are totally different things. They're just different objects entirely. Because I thought that was kind of similar to that difference. No, I mean, first of all, these are anachronistic terms, rationalists and pure assistants and so forth. These are terms of early modern philosophy which we can relate to these ancient philosophical schools with their much later developments but both rationalism and empiricism in the ancient sense would be theories of logic. They're theories about how we come to know things. Empiricism, we come to know things only through our sensations and perceptions of them. Rationalism, we come to know them through modules and processes in our own minds.  They're alternative in competing theories of logic. Yeah. I want to go back. So what's the definition of wisdom? Well, different philosophers have different definitions of wisdom. Aristotle's definition is that it's a combination of scientific knowledge and intellect or insight. But we're gonna be looking at a lot of different definitions of it. Do they agree on whether wisdom is useful or useless? Does who agree? Hellenistic philosophers? Well, the way the question's put is a bit awkward because I mean, everybody thinks it's useful. In fact, they all basically think it's an end. It's the reason you should do all other things. So in most of these views, in the Stoic view, for example, it's co-extensive with happiness itself. What it means to be prosperous, happy or successful is to be wise, period.   Now, there's other less stringent views than that, like ones where it's actually possible to be relatively wise or to be wise in some respects and not in others. But maybe the one thing that philosophers tend to agree on is that, yes, wisdom is a good thing and it's an end. They have total disagreements on what wisdom is, however. Okay, so that's really, in a way, that's something we're gonna be exploring in all of the texts throughout the class. So it would not be easy to give a brief answer to that. Yeah? Do the Stoics believe that all three were complementary to each other or could there be inherent contradictions? For the Stoics, there cannot possibly be any contradictions. They have a systematic philosophy. It's all interlocking. Every part of it has to be true. If any one part turns out not to work, then the whole system falls apart. And in general, in any given school, needs a consistent theory with all three since they interpenetrate and interoperate as I said. So if somebody modifies a view, for example, in logic or physics, then that would probably necessitate modifications in the other areas. Like a development within Stoicism that says early Stoics say there aren't parts of the souls, the parts of the souls, the soul is a unity and some later Stoics said, no, there's actually an irrational and irrational part of the soul and these parts are different. Well, that required developing different theories about logic and about ethics and about theory of emotions, actually. So, but within any school, it has to be consistent. If your logic wasn't consistent with your physics, then you don't have a school. You don't have a coherent philosophy. So coherence is the first most important thing.


What is variable costing and absorption costing? Those are two costing method that helps you determine your product cost. However, there are two different method. One is used internally, which is variable costing, and we'll see why and how and when used externally, which is absorption costing. Absorption costing basically is the gap method. So what's the difference between the two? It boils down to one thing, how we treat fixed overhead costs under both methods. Let's take a look at how so. If you remember under product costing, we include direct material, direct labor, manufacturing overhead, MOH, whether it's variable, whether it's fixed, all these one, two, three, four. So one, two, three, four are included in product cost. So we include those in product cost. And this method is called absorption costing. Absorption costing means it absorbs all the costs, whether the manufacturing overhead is fixed or variable. And this is the gap method. And this is what gap wants us to do when we compute cost of goods sold. So manufacturing overhead include both variable and fixed. It includes this one and this one. Now also we have period costs and under period costs, remember we can break down the period costs into variable selling and administrative and fixed selling and administrative expenses. Just kind of quick example for example, variable selling is the sales commission that we pay for our employees that conduct sales and fixed selling and administrative could be HR, HR people or salaries that we pay for sales people or salaries that we pay for the marketing people. So those are examples of variable selling and administrative and fixed selling and administrative, but those are period costs under absorption costing. Under variable costing, under variable costing, what's included in the product cost? What's included in the product cost is only direct material, direct labor and variable overhead. It does not include, the product cost does not include fixed manufacturing overhead. The product cost does not include fixed manufacturing overhead. So that's the key, remember fixed manufacturing overhead is not included when we compute the product cost. So that's basically in a nutshell the main difference. Now having said so, let's see if we can answer this question. Which method will produce the highest value for work in process and finished goods inventory? Simply put, which of the two methods will give you a higher inventory amount? Let's take a look at this. I would have to say product cost under absorption method will give me a higher inventory. Why? Because I'm including more per unit. I'm including more per unit. I'm including more per unit. So anything that's not sold, anything that's not sold, it's going to sit in my ending inventory that therefore it's going to give me a higher, a higher inventory. Why? Because fixed manufacturing head under variable, I am expensive. I'm treating it as a period cost. Therefore, it's not going to be part of my inventory. It's going to, so my inventory will always be lower. Okay, this is why absorption costing will give you a higher inventory value. Okay, and the best way to illustrate this is to actually work an example to see how this works. So let's take a look at this example. We have Harvey company produce a single product with the following information. Unit produced 25,000. Now it's very important when you are looking at variable costing and absorption costing, how many units were produced versus how many units are sold. So please follow the example carefully as we work through this. For this year, let's call it year one, we produced 25,000 unit, our variable cost per unit altogether, material, labor and overhead, is $10, our selling and administrative expense that's variable is $3, fixed cost per unit, manufacturing overhead is 150,000, right here, 150,000, and selling and administrative expenses that's fixed is 100,000. Now remember the main difference between the two is how we treat this number here, fixed manufacturing overhead, how we treat fixed manufacturing overhead, it's going to be the difference. So let's take a look first at how we compute the unit cost, the product unit cost. Let's look at absorption costing first. Under absorption costing, we have $10 for the variable cost, material, labor and overhead, this is going to give us $10. Now fixed manufacturing overhead, we have 150,000 divided by 25,000 unit what we produced, so our fixed manufacturing overhead is $6 per unit, therefore we can say that our unit cost under absorption costing is $16. Now under variable costing, our cost per unit would only include the $10, would only include the $10 and you're saying so what are we going to do with the fixed manufacturing overhead? The fixed manufacturing overhead, the 150,000 we are going to treat it as a period cost, what does that mean? It means this 150, it's going to be expensed on the income statement, all together it's going to go on the income statement. So let's assume that for that year we sold 20,000 unit, remember we produced 25, we sold 20, this means we still have 5,000 unit in ending inventory, just kind of want to make sure you understand the big picture and each unit was sold for $30 and let's assume there are no beginning inventory, we're starting this company, now let's compute net operating income using both absorption and variable costing. So let's take a look at absorption costing first, sales is 20,000 times $30 is 600,000, cost of goods sold is 20,000 unit, we sold 20,000 unit times $16, remember the cost per unit is $16, I want to break this down for you one more time, $10 was variable cost and $6 was part of the fixed manufacturing cost which gives us 320,000, sales minus cost of goods sold we call this gross margin, so the terminology is important here, for absorption costing sales minus cost of goods sold is called the gross margin less, less than we subtract variable costing which is 20,000 unit times $3 of selling and administrative and fixed overhead cost is 100,000, we expense 100,000 of fixed manufacturing overhead, I'm sorry fixed selling and administrative expenses which are those are period costs, so 280 minus 160 will give us net income of 120,000, so this is net income under absorption costing, now here's what you need to understand, we still have 5,000 unit and ending inventory, that 5,000 unit include an additional $6 per fixed manufacturing overhead that's going to be sitting in our inventory, so our inventory would include that 5,000 unit times $6 additional that was not that was not that was not expensed which is going to be expensed under the variable costing which I'll show you in a moment, so let's take a look at the variable costing, variable costing sales is the same, variable cost of goods sold is 20,000 unit times $10 only the variable manufacturing cost and we could also deduct we will also deduct the variable selling and administrative which is $3 per unit, so what we say is sales and here's an important formula sales minus variable cost which is variable cost include everything will give us something called contribution margin and this is important so what is contribution margin if I ask you what is contribution margin you would say sales minus variable cost and variable cost is period cost period as well as product cost so this is important so notice the terminology is a little bit different then we are going to subtract fixed manufacturing overhead and notice what happened we're going to subtract every single dollar of fixed manufacturing overhead the whole 150 is expensed the whole 150 then we subtract also obviously the fixed selling and administrative expenses all in all operating income is 90,000 so the difference between absorption costing and variable costing is $30 again where did that $30 came from under absorption costing there is we did not expense this $6 of fixed manufacturing overhead we did not expense $6 times 5,000 unit we did not expense $30,000 what happened to that $30,000 that $30,000 live in our inventory so because it was not sold it is in our inventory simply put to look at this picture again here's what actually happened cost of goods sold under absorption costing was 320,000 okay notice the fixed manufacturing expense the fixed manufacturing expense 120 of it was cost of goods sold and 30,000 of it was an ending inventory under absorption costing so notice what's highlighted in yellow 120 was cost and 30 was inventory if we look under variable costing what happened to that 150 this whole 150 was expensed and that's the difference that's the difference the difference is this 30,000 let me just the difference is this $30,000 that stayed with us on the balance sheet that's what made the difference the difference is that 30,000 that made the difference another way to look at it if we compute our variable costing net operating income which is 90,000 variable costing then we can add to it we can add to it any fixed manufacturing overhead cost that's the third which is the 30,000 y 30,000 5000 unit times $6 was the third we did not expense it under absorption costing 90,000 plus 30 will give us the absorption costing let's take a look at year two the same company now here's what happened in year two they produced 25,000 unit but that year they sold they sold 30,000 unit hold on a second this does not make any sense well yes it does make sense why because from the prior year if you remember from the prior year I had 5,000 unit from the prior year I had 5,000 unit and this is why I was able to sell 30,000 unit unit sales is $30 and the data is the same direct material is $10 selling an administrative it's $3 also variable a fixed cost per year is 150 for the manufacturing overhead and selling an administrative is 100,000 let's take a look at unit cost for each method it's 16 under absorption 10 under variable which is the same thing that we did earlier so nothing have changed let's look now at variable costing under variable costing we're going to have sales of 900,000 variable cost of goods sold 30,000 times 10 which is 300,000 the variable selling 30,000 times 3 is 90,000 sales minus variable cost will give us remember it's called the contribution margin then from the contribution margin we are going to deduct the whole $150,000 fixed manufacturing overhead we are going to also deduct obviously the fixed selling and administrative which is period cost so 5,10 contribution margin minus the fixed expenses will give us 260,000 and simply put let me just show it to you one more time this is so simply put sales minus variable cost gives me contribution margin minus fixed cost give me net operating income this is the variable income statement this is a very important formula now so net operating income is 260 let's look at absorption costing under absorption costing 900,000 of sales which is the same cost of goods sold we sold 30,000 unit times 16 gross margin notice the terminology once again is different 420 then we deduct variable cost of 30,000 times 3 fixed cost the whole 100,000 this one is expensed under both so net operating income is only 230 so what happened is this the difference between variable costing net operating income under variable costing was 260 and net operating income under absorption costing is 230 what happened is this under variable costing under variable cost and I'm sorry let's let's look at absorption costing under absorption costing you remember the 30,000 that we the third last year 30,000 dollar was the third last year now it's expensed in here so in here in cost of goods sold this year we released 30,000 dollar of cost of goods sold we released 30,000 dollar of cost of goods sold that was deferred from the prior year therefore our cost of goods sold is 30,000 dollar more than absorption costing so why didn't variable costing deducted this 30,000 variable costing already deducted this 30,000 last year therefore to reconcile the difference if we take variable variable costing minus anything that's released from inventory from the prior year which is we released 5000 will give us absorption costing so notice variable costing has more profit this year why does it have more profit this year because why did we have more profit this year I'll tell you why because we sold more than production what does that mean because we sold more than we produced it means we are going to expense inventory from prior year that includes fixed manufacturing overhead that was already expensed that's why variable costing will give us a higher net income in year one what happened in year one year one we produced greater than what we sold so we produced more than what we sold what does that mean it means some of the fixed manufacturing overhead that we produced was not sold therefore it was not expensed under absorption costing but it was expense under variable costing that's why in year one absorption costing has more income in year two variable costing has more income because we sold more than what we produce okay we sold what does that mean we sold more than we produce it means we are selling units from prior years and under variable costing those units will cost us less because we already expense that fixed manufacturing overhead cost therefore if that's the case we take variable costing minus the what we released will give us the absorption costing net income okay let's take a look at this at this basically a summary of the rules between the two if the unit produced equal to the unit sold for any given year that means there is no change in inventory guess what absorption costing and variable costing gives us the same answer why if you really think about it if you really think about it we expensed everything if everything that we produce sold so it doesn't matter how fixed manufacturing overhead is used because we expense it under variable costing we expense it under absorption costing therefore net income will be the same for both method if the unit produced more than the unit sold if we produce more unit and we did not sell them what's going to happen our inventory will go up our inventory will go up as a result if our inventory goes up it means we are not expensing certain manufacturing overhead cost therefore some of the cost is hitting an inventory therefore absorption method the absorption costing method will have a higher income than the variable method why because we hid that fixed manufacturing overhead cost and inventory in years where unit produced is less than unit sold unit produced is less than unit sold it means overall our inventory will go down because what happened is we sold units from prior year solding units from prior year it means your inventory will go down under this method absorption costing would give you a lower income than variable costing why because variable costing already expensed certain items in prior year and that certain items is fixed manufacturing overhead now we're selling those units but we're not expensing the fixed manufacturing overhead absorption costing is expensing them now in this year therefore absorption costing will have more expenses higher cost of goods sold therefore lower net income so this is basically a good summary of the difference between the two on net income simply put if you want to just summarize it variable costing it's a good for the cvp analysis which we're going to look look for later once again let me summarize it we'll take sales minus variable cost gives us contribution margin minus fixed cost will gives us net operating income this is an important formula it measures profitability better so variable costing it doesn't look at fixed manufacturing overhead because it assumes fixed manufacturing overhead is fixed therefore it's kind of in a sense it's not relevant for pricing decision therefore it's better for decision making variable costing is used for internal decision making okay variable costing is only affected by changes in unit sales not by unit produce and this is very important why because if you look at the examples that we worked in year one because we did not sell all the units okay absorption costing gives us a low higher income just because we did not sell all the units it's not because we were more profitable it's because some of our cost was hitting an absorption costing was hitting an inventory and this is really misleading because what managers would do if they're using absorption costing for for for pricing purposes they will produce more units as we produce more units they're fixed overhead cost per unit will go down as a result they think they are making more profit which in reality they're not all what happens is they produce more unit their fixed cost per unit goes down so absorption costing which is the gap method gives you the impression that fixed manufacturing overhead is a variable with respect to the unit produce so the more unit you produce in theory your fixed overhead cost is lower but if you don't sell those units then they're no good but that's not the case that's not the case fixed manufacturing overhead is fixed in total now per unit it's it's lower the result may be inappropriate pricing decision and product discontinuation or continuation you think it's your making profit but really you're not you're just basically you're it's giving you the wrong incentive to produce more unit to reduce your fixed manufacturing overhead cost so hopefully this is a good summary of variable costing versus absorption costing the best way the best way to illustrate this is to work a few examples which I will few questions to reinforce the variable costing versus absorption costing if you have any questions any comments by all means email me if you're studying for your cma or cpa study hard it's worth it


And so a plus lens, I kind of think that like this where you're putting basically two triangles bottom to bottom. And I like to think of that way because then if we I know that if I'm moving 10 millimeters down from the center, I'm going to have base up prison. If I'm talking about the right lens. I'm talking about the left lens I'm going to be adding base down prison. Based on Prentice's rule, patients reading one centimeter below the optic center. And so we're getting 1.75 prison doctors from the right eye, minus 2.25 from the left. So prismatic effect is for isn't that for space up in the right eye, right. Any questions on that one I think that was one that I sent out so we'll be at a chance like that already. Any questions. I guess I had a question, and maybe it's intuitive, but we have a base up prism in the right eye base down prism in the left eye. And so why are we adding the prism, as opposed to subtracting the prism. Good question so if you have opposite prisms in the two eyes. I guess if we had. Can you guys see my cursor moving around at all on here. Yeah. Okay, so if this, if this I was a plus 2.25, then we're getting the same direction of prism in both eyes. Does that make sense. There's the difference between the two at that point would only be a half diopter, which isn't going to induce very much prism. Because they're opposite signs. This left eye is bending the light up this right eye is bending the light down. And so it's almost like you're getting double the difference because each eye is doing a different thing. It's the dip it's, it's the induced amount of prism it's not the total amount of prism, the induced amount of prism. Yeah, and so that's that's one reason that you know somebody who the prison the prescriptions are pretty similar to each other you wouldn't expect there to be induced prism, but the more they have or especially if they have like a plus in the vertical and one eye and a minus in the other are you really have to pay attention to induced prism. Yeah. Now frankly, I in my mind I just think okay if there's a difference greater than about three diopters between the two eyes. This is something that I'll probably have to pay attention to less than that most patients don't complain about it. But definitely like if they are complaining and you look at the prescription and they are anisomatropic. That could be a reason so. Yeah, does that make sense. Yeah, yeah that does. Thank you. I included the ad. So, what do you do with that. Good question so the ad basically cancels it cancels each other out. So, you can get into some, some differences if you if you're talking about, I just don't know if I want to go there. But basically if you, if you include the ad, that would then make this left eye a plus a quarter. And then you'd add 2.5 plus 1.75 to this. And it would that the difference between the two eyes would still end up being the same. And the ad power is the same in both eyes just ignore it basically because it cancels each other out when it comes to parenthesis rule. Sorry, I just had a quick question as well. I'm Jordan on the intern. So if you're, I think where I got tripped up on this is that if the astigmatic axis the steep axis is that 180. I think I like ignored the sill because if they're looking like in the vertical meridian down isn't that the flat axis for the astigmatism so I just took the like sphere at like face value for each prison. Got it. So, yeah, that's why a power cross like this is something that's really helpful I think. I know in one of the video segments they talked about the power cross but I can't remember which part that was but so power cross basically just means you and you may have drawn one of these out but so for a power cross. So you take the first number and put it at whatever axis is in the second number so in this case, you put the plus one at 180. You add the two together and put it 90 degrees away. You take a plot you put this plus one on horizontal at the astigmatism. So plus 1.75 on the vertical. When it comes to parentheses rule. We're really only paying attention to the vertical especially what it says it's looking at 10 millimeters below almost every problem that I've seen is if it's somebody looking down in the glasses. And so you really. You do want to put it on a power cross and maybe just draw really quick these triangles. Just to help you visualize is the image getting pushed down. We have based up prison or based down prison. But yeah, I always put full powers on there just so I don't get tripped up by that. Yeah, and if you, you know, if you're thinking retinoscopy and I do have some retinoscopy problems in this presentation. You know, then you're talking about okay the beams falling across like this and yes I'm measuring the horizontal meridian, or now I flip my bean up my beam like this and I'm moving it up and down. And I'm measuring the vertical meridian. I wouldn't think of it like that in these problems I would just, if you see the prescription the glasses prescription I would just put it on a power cross really quick. If the ad powers are the same I would just ignore the ad.  At the same time you should be able to take the difference between the two and come up with an answer. Perfect. But yeah, we'll do, we'll do a few more of these problems as well as practice rule because they're, they're high yield on the test. So I hear if you and if you include the ad. And the right eye in the vertical meridian you're still eight but then doesn't it flip the prism in the left eye because you turn into plus a quarter in the vertical meridian. Is that true or no. It would, it would flip that prism but you're still basically taking the difference between the two. So, even though that is now technically base up it's much less base up than the right. That right eye is much higher so even though. So, yeah, like basically plus 4.25 in the right eye, and you have plus a quarter in the left 4.25 minus 0.25 still comes out to be for diopters. And then you're one centimeter below. So even though now that left eye would technically be base up, you have much less base up in the left that you do in the right and the difference still ends up being for diopters. That makes sense. Yeah, sounds good. Sounds good. Okay, we'll do it. We'll do it. What's that. I was going to say like, like the, the bifocal ad has to cancel out right because it doesn't even specify if their bifocals are progressives. So like you don't even know, like at what ramp that it's increasing power so it can't actually calculate the true prism from the bifocal or progressive ad right so it has to cancel out should not given that information. Correct you'd have to know if it's the seg the seg height. Different things like that. But once again if the if the bifocal power is the same. Really you're just dealing with the vertical power of the distance prescription, you can just kind of ignore that so. Yeah, unless the seg heights were different if the ad powers were at different levels and you might have to take that into account. That's getting pretty complex for like a problem that's only a minute long so. We'll get some more practice of these things because I think they're high yield they're, they're really helpful so. Okay, let me try to switch back to the who will go on to the second one. Nice. JCC and the lead here. I'm not even sure why it keeps points but probably some brownie points at the end I guess so. Okay, so question number two, can you guys see this. Yep. Okay, can you guys see the actual presentation view now. Okay, so very good job on this one. This is talking about a telescope, plus 20 lens minus 40 objective. One of those equations on that equation list today, but it should have been sent out by lane. It's this mag question. If you have a plus eyepiece lens and in minus objective lens just in your head if you have opposite science. That's a Galilean telescope. And this one's a little different because basically they're holding it backwards. Anyway, based on the equation, we have 20 over 40 which is a half point five X. So, the difference between their focal lengths ends up being 2.5 centimeters. So very good job I think there's only one. I can't even see who didn't get that right just. Oh that was that was me sorry I flipped my, my eyepiece and objectives in the. Yeah, my dad. No you're good. Okay, we'll do some more of these, these telescope questions as well. And, and sometimes drawing these out can be helpful to but I was going to keep the eyepiece and objective. In your head as far as that equation should be pretty good so. Okay, any other questions on this one. Go back to the food, especially as a rack up some points on this prerequisite. Okay, question number three, everybody pulling through on this one. What are you based on how quickly those were answered I think a lot of you did that one earlier. Let's go to the presentation. There was one more slide on the telescopes from before this is just to show where the focal point is in between the two lenses in the telescope. It's an astronomical. The focal point is inside so those are going to be longer. It's a Galilean focal point is an eyepiece behind the ocular. So those will be shorter telescopes. Here's question number three. So this e at the plane of the minus three lens. I think just drawing these ones out is the best way to do this to picture it in your mind and make sure that you're keeping your equation straight. Everybody got that one right any questions on question number three. Take that as a no. Here's the equation issues V equals you plus D. I think Jennifer you and I you learn this is V equals you plus P but very good. Yes, we're going to question number four. I'm loving these names you guys. Here's question for is just me or cannot select the right answer. Well, some of these. So there's a B or C. D and E. Some of these. Who would only give me four options that I could put in there so. Yes, I had to do some for anyone so if there's ever a question with five answers, one of the answer choices on who will have two options in there I didn't know how else to do it so. Awesome you guys all got that right. Again, so when you guys are figuring out question number four. Did you guys figure out the answer based on equations or did you just draw it and look at the image that was formed. I'm just curious how you guys came to that answer. I was told all minus lenses created upright virtual images and it's clearly smaller because it's closer than the object. Nice. Did anybody draw the chart in question number three. And then just use that to see the image look like. I was calculating the mag but I couldn't figure out where to get the sign that shows that it's upright. So let me share back to the presentation. So here's the drawing. And so, like I said for me whenever I do these problems, I draw it out, just to keep my signs correct. But also, on O caps you don't have an unlimited amount of time so if it's something that you would you look at it you can figure it out pretty quickly that drawing it no words but. So if you actually kind of drew out these lines doesn't have to be perfect but if you drew them out. And you'd see that the image is minified it's shorter. The image form is upright and virtual because it's behind the lens. So, the magnification use this quote this. This equation down here. So I'm sorry you were asking about the sign is that right. Yeah, so I used instead of the distances in my magnification I was using the virgin says, and kept winding up with a negative. A negative value on that on Magso like. So, I was using M equals negative you over V and had negative values for you and V. So, it was coming out to a negative magnification. Got it. I have to just look at the equation sheet again sir and plan through these back here. So this this equation here but then the negative you over V. Yeah, maybe, maybe that's the equation is not supposed to have a negative in front of it. I don't know. I will have to look. I, the equation that I don't want to use is that one that I put in in that equation list. I mean I do remember that negative you over V. But I will have to look back in time at my notes. No noise. Graduates and cobwebs on that one so I will put a star next to that. Okay. Yeah, based on, like I said, for me like if you've drawn the image already from the question before. Then you can just draw you can kind of tell what the image looks like and that's an easy way without even having to do any equations. The things that you guys talked about already though, generally work pretty well just to have in your mind as far as a bright virtual. So, okay. So you guys are doing is there is there a situation we didn't counter where my lens created either a real or inverted image, or can we just know that as a rule for our test. Good question so yes, a minus lens will create that, but it all depends on what they're asking the question in relation to So, you know because in this there's to a two lens system there could be multiple lenses. If they were saying, you know, in relation to the. No, I think I think if it's a minus lens of pretty much always would be a virtual upright image. But you just have to be pay attention to what they're saying in relation to because sometimes they might say something I just remember like, and maybe they were just complex questions back in the day, but they might say something like, you know, if from the perspective of the object. What what is this image, you know, look like, and they might just say like it's smaller and upright, but still be virtual so I think that I think pretty much keep that in your mind that it would be upright and virtual from a minus lens. I think keep in mind is just thinking about the incoming virgins to the lens. So if you have a lens system where the incoming virgins to the minus lens is like a plus five, and then that lens is a plus two. Then the outgoing virgins is still going to be a plus and so it's going to be a, you know that will when it holds so I think that's important to keep in mind. Gosh, I think that does make sense. Thank you Jennifer. Once again, we're drawing it out might be helpful, but yeah. It's a single end system then it would always be the case if the lights coming from the left, but the very the incoming virgins definitely matters. Okay. More practice problems. So please keep in mind I believe this is still the case where you have 480 minutes for 460 questions. That's a little over a minute per question. Some questions you'll fly through some of these optics one just take more time. But if you find that you're getting stuck on something just, you know, come back to it but no calculator so kind of do some today. We already have some scratch paper and pencil. So this is the next question let me put it on the food so you guys submit your answer. JCC prisms on a roll here this is good stuff. Okay. All right. So it looks like a couple of you got fooled by the working distance. Let me see. All right. Who is JCC. That's me. Nice. Optics master. Jennifer, can you explain why the answer is C and not. I think the other one, excuse me, why the answer is the. So you have to take into account your working distance when you're doing retinoscopy you as the observer are only 50 centimeters away, you're not at infinity. So you have to take one divided by point five to get two diopters of, you know, kind of induced virgins because you're an observer closer. So whatever answer you get like the plus 22 you just have to take two away from it. So you end up with a 20 and a 25 instead of a 22 and 27. Nice. So can you guys see the presentation now. Are you guys still seeing the cahoot or are you seeing the presentation now. We're seeing the presentation. Okay. So this is exactly Jennifer saying so. We're doing retinoscopy working distance matters a lot. And so it should tell you a working distance and you have to account for that urgency. So like you said one over one over point five is a minus two. And so, if you put your, your retinoscopy powers on a power cross, take that virgins into account will end up with a plus 20 and plus 25.  You forget that working distance. And I am and I am very impressed you I you all got the powers on the right lines, which with retinoscopy can be a little bit tricky sometimes. Any questions on on this problem. Going once points. Okay. Great job on that one. Let's go back to the compute everybody rocking it on that one. spherical equivalent is something that thankfully is pretty simple. I don't know how high yield that is but it's good to have, have that skill down clinically and potentially on the test as well. You guys all got that one right basically. Here is the equation. The sphere plus half the sale. And I guess the only thing that I would pay attention to be close attention to using is if it's plus sale or minus sale. Because that would determine if you're either adding or subtracting from the sphere power. Do you guys all did really well enough. So, oh, there's a sneak peek at the next question. Any questions on spherical equivalent that's that's pretty simple stuff. Any questions there. Any questions on the next question. Hey, some Jordy. Talking about that one. So optically empty just just made a push there who is optically empty. It's me. Allie. Is that right. Yeah. Awesome. So, Ali, can you explain how you got that answer and how you got it so quickly. With prisms. They work off like 100 centimeters being how much they're going to displace. So, with this question. They, um, I think it was like 30 or 33. So I knew at 100 centimeters, it'd be six. So then 30, it'd be about two. Yeah. That's a good presentation here. Exactly. So we're at 33 centimeters, which is about a third of a meter, right. So if it's a six prison after you take a third of that, which should be about two centimeters. Great job. So you can draw this one out as well. With optics drawings are usually helpful. They just take a minute to draw. But yeah, if you have that 100 centimeter number in your head. You can just figure out how what length. Or how far from the prison they're talking about. Do a quick ratio and apply that to the prison. I think there's one person that didn't get this one right. Are there any questions. On prison. I just put the wrong ones. There we go. All right. Okay. And another thing to keep in mind. I'm going to go back to prison. Maybe applicable later. We'll see. For angles under 45 degrees each degree. Equals approximately two prison diopters or two prison doctors per degree for angles under 45. The big one I think they're going to be testing on is, you know, is to find this deviation of one centimeter at one. Love it when everybody gets it right here. So this basically explains. So far point in your point. So for an uncorrected mile. Our point of 40 centimeters. The power is just one over negative point four meters 40 centimeters. It's up to minus two and a half. Great job. The next question is also related to this. This minus two and a half. So don't forget that number yet, but. Any questions on how to determine. The refractive error for a mile or a. Hyper over any questions on that. Okay, let's do the next question. Like I said, it's related to question number three. Yes. Okay. So one for num or for answer D. And then five for minus one and a half. So what are the questions making the remove whose four eyes. I am. Yes. So hard. So, Ariana, can you. Can you tell us how you got that answer? Yeah. The patients. Regular far point. Told us that they have. Normally minus two. And then they would have to accommodate. So how do you know if you're supposed to like add them together or take the difference there?  And so he has. Power in their eyes. And then to get to this closer point, they would need. Minus four. And that's calculated from the 25 centimeters. So the difference in power. Is what they have to accommodate. So how do you know if you're supposed to like add them together? And so he has this. Near point like he's near sighted. And then this is now a closer near point. They used to get to. Awesome. Yeah, absolutely. So once again, if you ever can't keep that in your mind, you could draw something out really quick, but. Yeah, it's basically just taking that difference. And you end up with one and a half diopters. Of accommodation. Yeah. It's much, much easier if you put it into the powers and diopters to do a problem like this when you're accounting for equation. Excuse me, accounting for accommodation. So yeah. And they're, do they do questions on O caps that are kind of sequential. Are there. I don't think so. Not necessarily. Okay. So they could easily come. Yeah. Again, I feel like sometimes they had a two part question. Maybe like two questions are tied together. Got it. So they could put something where these are either separate or together easily. I mean, I just split it up just so you can do that, but. Yeah. Anyway. Putting it into the power and diopters is very helpful for some of this. Any, any questions on. Accounting for this accommodation right here. Next question. True or false. So glad you all got that right. Okay. So these next questions are tied together. Even if they don't have this type of question on. Oh cap where there's multiple questions in a row together. I think that it's actually very, very valuable. Practice to do this. So. So this is question number five. And you guys see it on the presentation there. Back in presentation. Does anybody need more time on question five. It's harder without being able to tell when you guys return. Okay, I'm going to move on to question number six. Here's question number six. Okay. So we have five more seconds for this one. Okay. Question number seven. Anybody need more time for question seven. Here's a question eight. Is 1.5 the distance between the two lenses. Yes, it is. Great question. Yes, it is. Anybody know that need more time on this one. Let's go question nine. The last one in the series. This is where it'd be great to be in person. Okay. I'll be COVID. Five more seconds. So. Are you on here? Yeah. I'm going to talk through Ariana's. Okay. Perfect. Can you tell me what you've got for question number five. Okay. So I got B. So you is minus one. One over four is point two five. And that's positive. So it's 25 seven years to the right of the lens. My wonderful brother. That's one of my favorite pictures. If you mind just kind of put that on. Don't show them that in the recording. Okay. So you ask question number five. The 25 seven years to the right of the lens. Awesome. And you just use that B equals you plus D. Equation for that. Okay. So the big thing here is just make sure you're keeping your science straight. If the object is to the left of the lens, which is the standard. Then. That's going to be minus one. Added to a plus five gives you that plus four. Plus is going to be to the right of the lens. So 25 centimeters to the right. Excellent job. All right. Any questions on this problem that anybody. How many questions on this. If you have any questions, feel free to ask Cole. He's got this one down. All right. Tyler, are you available? Yeah. Okay. So for question six. Can you tell us what you, what your answer was and how you got that answer? So I think the answer was. Sorry, B. It is real because it's a converging lens. So light actually passes through that point. It is if you draw the central ray from the tip of the object through the center of the five that are thin lens and beyond. So if you do the magnification equation, which states the image distance divided by the object distance, it should also be smaller. Awesome. So let me just go to the next slide here. Yeah. So. I just did a quick drawing as well. And you can also buy that see that it's inverted real to the right of the lens and reduced it is smaller. But absolutely just keeping those things coming in your mind. Okay. It's a converging lens. And then you can do the magnification equation. Jennifer, do you usually draw the rays or do you just. Do the equation and I don't know what to expect. Just curious. I like to think about the distances. So for, you know, this example, I forget how much it was, maybe 35 centimeters, but I'll do positive 35 over negative 100. So then I know it's minified because it's less than one. And it's minus. So it'll be inverted in real. Got it. That's great. That's great. I asked Jennifer because she's, you know, fresh out of optics boards and all that fun stuff. So yeah, there's a couple ways to kind of keep it in your mind. That's a great one. Just using the distances. So, okay, any questions on question six. Lydia. Are you on here? I am on yes. Great. Can you pull up question number seven here. You tell us what you got for question seven. Yes, so for question number seven. I said that the size of one second. The size of the intermediate object. So it is smaller. I actually thought that it was one half of the size, but based on the drawing and the previous question, I believe that the answer should be a force of the size. It is one fourth of the size. So. Yeah. So equals you plus T is a good way to kind of determine how. Or what the size is. So once again, like if you draw it. If you just, if there were these series of what is that four or five questions together and you did a drawing initially. And just drew where the image was, then a lot of these questions could be answered just by looking at that image. But it does take a little bit of time. So just as long as you're going to be able to keep that kind of image in your mind. Then you could just answer with that. You can also just use the distances, like what Jennifer was saying. The distance of 25 centimeters versus one meter. That's one fourth of the distance. So we expect one for the size. Yes, or you can just use the equals you plus the equation. I think the picture is very helpful the drawing. Yeah, pretty helpful. And so it goes over in the video. How to do these drawings. And also, so that grand rounds on Wednesday. I had not seen any of those resources on the Academy website. I'm going to try to incorporate some of those into my pre-work for next time. It sounds like some of you, each UI twos have been able to utilize that resource. But when I was browsing through it looked like it had some really good information on telescopes and I think one of them was a tracing.  And just you can continue to continue that one on for infinity. If it's a converging lens, you would. Yeah, I guess you do kind of need to know the distance away from where the lens meets the horizon. So it would be converging and just draw it. Anyway, it goes over on there. I don't want to take too much time doing that, but if you, if you learn how to ray trace quickly, it can be super helpful for questions like. Any questions on this one. Okay, for question number eight. Harry on it. Can you walk us through question number eight. Yes. Okay. Question number eight. The, the new you for the new image suffrage and for objects. I first placed the object 25 centimeters to the right of the plus five lens, which puts it at 1.25 meters to the left of the minus two lens. And then my new, that's my new object. So my new object versions is. The negative of the inverse of 1.25. I made that a fraction, which is like negative four fits. And then I added in the. Our lens, which is minus two. So now it's minus two added to minus four fifths. That's negative 14 fifths. And then our new distance is the inverse of that, which is five fourteenths. That's about a third. And it's negative. So it's to the left of our new lens. So about a third of a meter to the left, which is D. Yeah. Very good.  You have to make sure that your object starting out is in the correct position. 25 centimeters to the right of the first one. Take that difference. And then it's just a matter of keeping your sign straight. And that equals you plus the equation. And exactly. And sometimes you can get caught up on exact numbers. So things like. The dimensions or rounding can be very helpful.  It ends up being about a third. So close to 33 centimeters to the left. And that while there's not an exact 33. To the left option. There's a 36, which is pretty darn close. And so that's what you go to. Yeah. So that series of questions, I guess we have one more. So let's do question nine and then we'll. We'll talk about how helpful you since our, but any questions on question number eight for now before we move on. Okay. Let's go. Tyler. Are you on here? Yeah, I'm here. Okay, can you walk us through what you got for number nine? Um, so. Yeah, I mean, and if you don't know, that's totally. No, I think. I'm a so given that it's a negative two diaper lens. My assumption is that it's going to be a. Virtual image, which gives C or D.  Well, thankfully. You were right. Um, once again, just coming. From just like a, just a sheer rate tracing. If we started out with our initial. Our first image ends up being right here. Okay. And so if you had drawn this out or just, you know, and then you drew your primary rate through the center of that second lens. And then you knew that the new image was to the left. You could tell just by this image, if you just put about where, where it was on here on the drawing. It's going to be reduced. It's going to be virtual. And it's going to be inverted. It's going to be inverted. It's going to be even just drawing like one single rate can be pretty helpful if you know where the object image or ending up. But yes, this is a case where since it is a minus lens that it is inverted. But yeah, I, I find for me personally drawing it out. It's very. Great job. Okay. So I think if you were able to do those questions. That is awesome. I mean, if you got all this right. I think that's going to cover a lot of material as far as images. I mean, a lot of high yield stuff.  That's what most of this is just keeping your sign straight. I don't know that ever do anything this complex in a row. Okay. So that's questions five through nine. Any questions on any of those before we move back to the boot. Okay. So I wanted to. Quick question. I think I remember. At somewhere along the lines, somebody saying that. A. Hyperropic. Well, a. Negative lens. So like a negative two diapter lens will only produce virtual images. But a plus diapter lens can produce virtual or real images depending on. Where the object is. So that was one thing that Jennifer was talking about earlier. Yeah. For both a plus or a minus lens, the virgins coming in. Matters. As far as the type of object that will be produced. Okay. And so. If. You know, if this image was inside the primary focal point of the lens, that will determine. If it's a real or virtual image that is produced. And if it's to the right and the left. I. Cannot imagine that they would do something like that on. Okay. Because it would take like those problems on tests that we did in optics would take five to 10 minutes each to calculate sometimes putting our clean, like having to draw it all out. I don't know.  Have you run into a scenario like that? Not that it's all about the test, but I'm just curious. Has there been a scenario where. Where they had put an image inside the primary focal points that you were dealing with. Something different, I guess. I feel like. In my memory, they could. The optics could be anything like there could be a straightforward question, but there are also questions where you. Really, you have to do some work on it. So. Yeah. It didn't surprise me. So even if it was inside the primary focal length, if you keep the V equals you plus D equations straight. You should be able to determine how far to the right or to the left. The image is produced. And if it's to the right of that lens, it's going to be a real image if it's to the left of the virtual. And really that's what it all comes down to is. Where is that image being produced to the right or to the left of the lens.  If it's inside that primary focal point. But if you just keep your equations straight. And then you should be able to determine if that image is to the right or to the left of the lens. Does that make sense? Hopefully that does like that vehicles you plus deal with these lens equations. I mean, if you only knew that equation, you could come up with the answers for almost. Okay. Let's, let's keep cruising. We're going to go back to who can you guys see the commute screen now. Yes. Okay. So here's the next one. Double points. Okay. I don't have a double points, but. I had about 10 seconds. Nice. This is why it was double points here. So this one was obviously a tough one. Kind of through a curve ball there. Let's see. Optically empty. Nice. Solid work. Hey, Ali. Was that a guess? Nice. Okay. Does anybody know what equation we would use here? I know. I think you still do. You plus D equals B, but you have to. First calculate the power of the mirror. Which is a two over R. I think. Two. So the power of the mirrors. One day after. And so I think the object distance was 33 centimeters. So the last one is. Minus two. So your object distance is then. 50 centimeters. So your image just. Sorry. Your image distance is 50. So it's 33 divided by. Or 50 divided by 33, right? Let me share my screen. Okay. So exactly right. So. Power of the mirror is two over R two over the radius. So you have to calculate. So we have to calculate that power first. Two over two is one. Our object. This plays 33 centimeters to the left. Minus three diopters. And then the, so did any, was everybody able to get this minus two diopters for. The image. Did anybody get to that point.  I kind of got my time to make stuff. That's where. Where I lost, but yeah. I think it makes sense to think of a. The mirror as a lens. Which is, which in my mind, when I think of it as a lens, then I think of the U plus the virgin's formula. But if I didn't think of that, then I probably wouldn't have gotten to the virgin's formula. I don't. I didn't fully. I still really understand how you know, it's like a plus versus the minus 1.5 X. That's what I. That's what I'm still kind of stuck on. Got it. So it. It all comes back to this equals U plus the equation. And this is once again, we're drawing it out can be helpful just to keep. Objects and images. So. Exactly right starting out so you have to figure out the power of the mirror once you get that power of the mirror. That ends up being a plus one, then you can plug in that be equal to plus the equation. The equals so you are object distance is minus. 33 centimeters because it's to the left of that original lens.  Be. We take minus three plus the one from the lens we get minus two so both are B and are you are negative. Our transverse magnification equation is transverse mag equals you over. And so you would plug the minus three. Over the minus two. And then you get a plus one point five X. So in this case, it's all just based on that B equals you plus the equation. So if the signs get mixed up, it'd be super easy to get thrown off on it. It's a plus or a minus. But since you is a negative. The negative three. And B is a negative, a negative two from our equation. The negatives cancels each other out. You have a plus one point five X. Does that make any sense? The, the signs make sense in that, but what is it? Do you know what it means like the real world? Is that signifying like inverted or upright? If it's plus or minus. Jennifer, that would mean it's an upright image, right? She's on. Yes. So the plus signifies that there's an upright. I believe so. Yes. And magnified by one point five times. And then the negative would mean it was inferred. Okay. Cool. Thank you. Yeah. No bro. So that was a tough one. Obviously that's where the double points came from. So. Solid work on guessing that one correctly. Yeah. Keeping the sign straight. Makes a huge difference, but. Taking a second just to draw it. Draw it out. Okay. Let's go back to the boot. I'm a pretty nice person in real life, but this question does not. Make me a nice person. All right. Three seconds left. So. Let's see who got that one right. Okay. Did anybody actually try to do the math on that one? I tried, but full disclosure didn't get done. I just guessed what I thought might be about, right? Yeah. I hope that. That's all that work. Did anybody, I mean, were those all just guesses or did anybody have. Like some thought processes to what, how they came up with their answer. Let's see. Arianne, I think you got that one, right?  All right. Well, like Jennifer. My calculations were starting, but then had to quickly click one before finishing. I was starting to use. Like a lens maker formula with the. Like the power is proportional to the index of refactions, but did not get far and writing everything down. So how did you come up with the, an educated guess on that? It was asking for a corneal power. Which is close to 40 in a real eye. So I went with the answer close to 40. Awesome. So let me, is that kind of what everybody did? Was there any other clue that led you to. To answer D for anybody. You can also use the thick lens equation. Let me just share this really quick. So. You can actually come to this answer using all these equations. I'd be crazy to try to do that when you only have a minute and seven seconds per question on average. So basically the thing to pay attention to, if you get a question like this, there are good ways to make educated guesses on this. Like Arianna said, like a corneal power is close to 45, right? But that's in air. Okay. So the, the kind of key words if there is such a thing as assume index of refraction of air equals one. And it gives you the cornea and the aqueous. So if it's asking in air, it's going to be probably pretty close to 45 because that's what the average corneal power is. But it could give you this in water. Okay, it could say that somebody's opening their eyes under water and that changes things drastically. So as kind of a rule of thumb. If it's in air, it will be close to 45 diopters. If it's in water, it will be close to minus a half diopter. Like the lens maker equation and stuff is, and the thick lens equation, both very useful. And, and frankly, I think, you know, you could calculate those out. But something like this, if you just, if you can just keep that in your mind, like, I mean, I use this in contact lenses and in cornea, I use this in all the times that the average corneas around 45. So that's something that's good to have in mind clinically as well. But if you just keep those two rules kind of in your, in the back of your head and then pay attention to if the index or a fraction is in air versus water, that should be able to help quite a bit. So that was kind of a mean one. I didn't actually expect anybody to get that question right in 90 seconds. Do those rules. Make sense to people. Any questions or in terms of that. Okay. All right, let's keep going to the next good. So kind of a split on that one. All right, so let's see. Dr. petty my team over here, we just clicked a little too fast. That was our bad. No, you're good. Let's see. Cole, can you tell us what your answer was? Well, I was the one who got it wrong. I changed the sign too early. But basically you add the plus still to the sphere. And then switch the sign as well as change the axis by 90 degrees. So we did that we just did it incorrectly. All right, so let's go here. I would normally do a seventh inning stretch, but we got to get through all these questions here so. Yeah. So to switch from plus still to minus still form exactly what you said, you add the seal and sphere together just make sure you're paying attention to the signs, flip the sign of the sale and then change the axis by 90 degrees. We come up with the question. I'm curious, did anybody like mess up on that? Without just accidentally hitting the wrong button. I get any questions on how to switch from plus still to minus so. And vice versa. I got something that could easily show up and also very helpful in real life. You know, if you're switching back and forth between contacts and glasses. Nice job on that one. Here's the next question. Okay. I'm going to give you a little bit of a split again on that one. So let's see how it came up. Remind me who prison is. I don't know who that one is. That's me. Abigail. Okay, can you tell us how you came up with that answer? So. I knew that. Each prison. Diopter is equal to like half of the degrees when it's less than 45. So I picked the closest to 20, right? So the closest to 10. Exactly. Yeah. So, okay. I think that was something that I mentioned on an earlier slide about prisons. The exact number is 0.572 degrees. Times the amount of prison.  So it's, you know, it equals 11.4. That's about 10. If you just, it, like I said, sorry, let me back up. If it's less than 45. Then it's about half of the amount of prison. So that's a pretty good rule for a most prism. Certainly that we're prescribing is going to be much less than 45. Did anybody accidentally get that wrong? Or just not remember that? Look like maybe there are a couple of them. Just keep that in your head. Degrees half the prism. As long as we're under 45. Next question. Starting right now. This is a telescope question. That's rock that one. Can you tell us how you came up with an answer? So I, I'm not participating in the Kahoo chat. I have to be honest because I was late because I was. Oh, I'm so sorry. But it is because it's the, like the way the. How should I explain it the way the. Lenses are aligned. It's the Galilean. And then can we go back to the numbers of the question, please. Sure. Let me pull up. And if you do want to hop in, hop on the pin and pattern around the bottom, if you want to hop on there at some point, but let me go back to the question. Okay, so here's the question here. Yep. So. If you're subtracting the focal length of it. From the, from the two objective lenses. That will tell you that it's the. Galilean lens. And it's like, yeah, you're subtracting 10. Like minus 10 plus four. Let me put this up for you. So, yeah, so one thing to keep in mind, as far as like Galilean versus astronomical. If they're two plus lenses, you know, it's astronomical, which is going to be longer. The focal length is going to be in between. If it's Galilean. Then you're going to have a plus lens and a minus lens. I guess that's how you know that it's Galilean plus objective and a minus ocular. And then the focal point will be outside. So it's going to be a shorter telescope. So one thing to keep in mind, if you're given like the powers to find a distance, you'll, you'll want to take the inverse of the power. To find the focal length of that. So one over four. Plus one over a minus 10. You add those together. So 25 centimeters. Plus a minus 10 centimeters equals 15 centimeters. And yeah, so.  And the astronomical one is longer. If it's longer, that means that the focal point is inside or in between the two lenses. You'll be able to, like, that will help you to answer a lot of the telescope questions, just knowing that. If we just look at here, we got a plus four and a minus 10. Okay, well it's a plus and a minus. I know it's a Galilean that eliminates C and D. And then you can go ahead and, and plug in those powers. You take the difference and then that's about 15 centimeters. So, thank you. Yeah, you're very welcome. Yeah. Anybody else have any questions on this one? I think this is something very typical of what you might end up seeing. So you've been kind of those just general rules. Any other questions on this? Okay. Because the next one. Okay. I'll move that all over the place here. Telescope ones are tricky.  JCC man. Okay. So, for angular magnification. Server that just go. The answer is C minus five X. This gets back into the question of the minus versus plus on magnification. What does that mean. So the equation is for the telescope is magnification equals a negative power of the octave over the power of the objective. The reason that the negative and the plus matters. So a negative magnification will give an inverted image. So it's still magnifying it when you use an astronomical telescope. It's still magnifying and it will still give you a larger image. But it will be inverted. In other words, everything that you look at will be upside down. It's a different formula than the formula that's like. Diopter of the eyepiece over diopter of the object of the, of the, like, objective, I guess, is equal to magnification. I mean, it's for all the way back up. I think I may have confused ocular and objective or eyepiece or something. You may have just seen the answers. I think in one of my lectures I did before before we had the reverse classroom. I had some pictures of what the different telescopes look like.  An astronomical telescope usually has a band in it. They're not straight. So a lot of the telescopes you just see like somebody at a football game it might have like a band in it. That's because they have to have. They have to have mirrors in there to fix the image so it's not inverted when you look at it. So an astronomical telescope. There's just kind of some rules with them for an astronomical telescope would be greater than 4x. You'll have a plus power ocular or both lenses will be plus power, and the magnification will be negative or inverted. Yeah, I was just looking at that equation for the magnification. The one that is on the handout that I gave you guys. And it doesn't have that minus there for some reason. I don't know when I was looking at this, this problem online I definitely have that one so I'm going to have to look at that equation again. Jennifer do you remember if the equation has a minus in it. It does. The equations minus the power of the I piece over the power of the objective. That's my thought but for some reason the one that is on the paper which I just, I got from the vocab book. Because the image, they're talking about its image distance and object distance. And the image is a minus because it's coming from the left, whereas the object is a plus, if you're considering it in that way. There's a separate equation that's the telescope magnification equation that's the second to last one that doesn't seem to be wrong. Yeah, yeah, because it should definitely have that minus in there. I've never heard the telescope magnification. Because that's how you know that the astronomical hasn't heard it magnification so I will fix that on your equation sheet. The whole stars. Yeah, we only have two minutes let's do a few more questions if we can. I'm flies when having so much. I thought I'd fixed all the issues with last year. Okay, here's number 14 be glad you guys are nailing. I'm sure so. Okay, I think it's all about that one right. I'm just going to show you this page really quick so present after one centimeter at one meter distance we have half a meter. So we need to double that. Object size to get a prism. Yeah, you guys all got that right. Any questions on that one. They will keep moving through to get through as many more of these as we can. Do you see the good boot again. Yeah, we can. Okay. So this is that same equation that we were just looking at that and equals the power of the ocular over. I'm sorry the minus power of the ocular over the power of the objective. So, how are you able to tell astronomical versus gala way, Jennifer. We know it's astronomical because both powers are positive. Right. And to Jordan. Were you able to come up with, or how are you able to come up with the magnification on that. It's just the telescope magnification equation. So it's just the negative power of the piece over the objective power. Great. Yeah, you guys are really well on that one type race. All right. Okay, next question. You might get through. Fantastic. All right. There's kind of the images here. Ariana, can you tell us how you got that answer in the right eye. So first of all, we're looking below that. So we're interested in vertical in the right eye. The cell. Is actually acting at 180 so we can ignore the cell there. And then we multiply one centimeter from the 10 millimeters times minus three and get minus three and then in the left eye. So minus one and then the plus one that's acting vertically cancel out. So, left eye is zero. And then the minus three, like you drew there is, it's a diverging lens, it's a base down so three base down on the right eye, nothing in the left. Awesome. Yeah.  I'm just curious. What's most effective for you guys because everybody got that right. Did anybody draw a picture. I draw a quick picture, just two quick triangles. I draw two. May I ask a question just to see if I understand this correctly. If the patient was not looking telling 10 millimeters below the optical center but 10 millimeters above the optical center. The only thing that would change is that it would not be a base down but it would be a three day after base up. Correct. Yes, and that's where drawing the picture is helpful to see which direction the prison base is going. So, drawing this little question, or excuse me, these little triangles will show which direction the prism is now are going to do great job saying okay that you know they're looking one centimeter below. So we know that we only have to worry about the vertical. If this is saying that they're looking 10 millimeters to the right, then we'd be worrying about these horizontal numbers K which would end up being different. And in this case would end up being a different answer. Just pay attention to how far and which direction. The patient is looking all the ones that I've shown here have been vertical and looking down, but they could technically ask any direction and and amount I would hope that they would do 10 millimeters one centimeter or two centimeters something to keep it simple for you.  I have a question on that though they were looking up it would end up being base up prison. Any other questions on this. Okay, I think that time for our last question to the right or to the left I don't think I would get to that answer. So how would the equation differ if this patient would look 10 millimeters to the right. Like, how would we describe that with the basis, it would be. If it's looking to the, like it would be the base out. But how would the present day of just be good question so, so let's say that the patient was looking to the right. Okay. So that now we have to like think about the patient's perspective so that would actually move what we're looking at over to the left on this can you guys see my cursor there. Yes, yes. Okay. So, in this case 10 centimeters we would multiply that by the minus two. So two minus two times one centimeter. We'd have two prism diopters from this lens. We would have one person diopter from this lens because minus one times one centimeter gives us one. And in this case it'd be still be a base out. If you drew the picture you'd have triangles like this. Hopefully you can kind of tell what I'm doing from a cursor there. But it would be base out in both cases and then we just take the difference, a two person doctor minus one person doctor means that they would have one person diopter base out in the right eye induced by that lens system. Wonderful. Thank you. Yeah. Yeah, great question. Let's do our last one really quick. The great double points. Really just want to hash these ones is apparently pretty heavy. Oh, can you guys see it so I can you guys still see the cahoot on there. Yes. Okay, perfect. All right. Got that. So, see, see could be either, or I guess it was C or D so which one did you guys come up with. See, see. Great. Let's see. Ali, could you just walk us through this one really quick. Sorry, I missed the beginning of the question so I was still doing my math, but it is similar but the thing is that you have to flip it to, because you gave it to us and negative. So, right. Correct. Yeah. So you have to flip that, and then it's similar to what we did before so in making your power crosses so it'd be like the right I had minus three at the 90 minus four at 180. The left was minus seven at 90 minus six at 180. The right was minus three minus seven to do the multiplication with the 10 millimeters below. I think I can't see the problem. No, you, you got it totally right so. Hey, you're exactly right to you put it on a power cross. Now you had mentioned, you know, putting this in plus still form first. You don't necessarily have to do that. I know that that's kind of how we think in ophthalmology. Yeah, so, so it's completely fine to do that.  And then you just add these two together and put it 90 degrees apart so you could just go straight to the power cross. And at the same time, you know, like, if you're more comfortable working and plus so just put that in plus certainly quick, and then put it on there, but you could technically save yourself a step there, but absolutely did the rest right. We have a minus seven in the vertical on the left eye minus three vertical on the right. Take the difference or you know, together basically and you get minus four diopters were 10 millimeters below. One centimeter. So we have four base down in the left eye. Great job. Any questions on that one. Back to our who here. Let's see who took the podium here. Keplerian King. Who's the Keplerian King. I don't even know who that was. That's cool. Cool. Nice. Okay. Well done you guys. Yeah, optics. There is a ton of potential things to cover if you watch those videos. I hope you paid attention he kind of has like the top 10 list of hot ticket items on the test of high yield material. And I think in his lectures he does a really good job covering those top 10s and a few other things as well. I tried to gear, you know this towards most of the top 10 items and a few other things mixed in. But I know we're kind of at a time does anybody have any questions. This is the last couple minutes here. Before we end. Okay. Thanks Dr petty. Hey, you guys are so welcome.