Understanding Units and Measurement Concepts

So hello SBWB gang seniors Welcome to the party How are you all? Let me know in the chat Fast and furious How are you all? If you are new to the channel Like, subscribe and share the video As much as possible Because students We are going to start today Which is third part is particular chapter which is units and measurement students meritorious a each and every concept many of the tailway pariah here but apparently us co-users did say or time to time a garage may not complete clear hookah so I hope up so he could each after bohati a chitarra cases a much may I ahogha or at the same way job II thores a hard concepts this is a parallax method we're up movie up simple way may so much may are choking on get together a bit students are uncomfortable they can a Jana have which is third part care gourmet Sharaf Peru come this wouldn't you you already know kikol we have a witness about how we can change degree into the radian after that radian into the degree the kucham make conventions they can 8-10 points. Then we discussed some things about parallax method. We saw 3 types of parallax method. First one was measurement of distance of the stars or planet and also the size of the planet. After that we have witnessed about the very small distances which I told you yesterday in one point. The very small atoms and molecules, the very fine things We can't see it with vernier caliper or screen gauge For that we need electron microscope or tunneling electron microscope Okay? Yes? Clear? Okay! Okay! Now students pay attention, what we are going to start today By the way, did everyone completed DPP yesterday? Yes everyone, did everyone completed DPP yesterday? Tell me in comments Because students, yesterday I told you that this is what you have to learn on the yesterday basis. Before the session ends, brother had told you to do these things. Hello, pay attention. Don't look here and there. Don't sit and comment. Don't talk about here and there. I am talking to you. Look properly. Okay. Important things are going on. One is the value of astronomical unit, light year, per sec, par sec. Okay. Each and everything brother explained to you in detail yesterday. I hope you all have done it. Like it quickly. Let's aim for 100 plus likes. Okay. Now students, what we are going to identify today or what we are going to see today is Accuracy, Precision, Uncertainty in the measurements. Means students, we are going to see three things today. And above this, above the errors, We will solve some numericals also. So, all students please take your book and pen. I will tell you in a very simple way. First of all, we will see what is mean by accuracy. For example, your brother used to say that these questions are possible to come in paper and there are chances to come in paper. So, obviously, the same type of questions used to come in paper. Obviously, they will not come completely because we do not make paper at home. But, Closest value used to come. Yes or no? You have to believe that your 10th brother has taken it out. Hahaha. Okay. So that means students, So accuracy is nothing but it is the closest value of the correct value. Suppose for example students, this is a particular scale. See this example properly. Okay. And this is also a scale. Now the actual value of this scale or the correct value of this scale. Okay. What is the correct value? 15 cm. But when I measured it, it was 14.95, 14.94 or 14.93. That means it is closest value. Yes or no? Is it closest or not? See students, we can write 14.95 as 15.00. Why can we write? Because this is the closest value. Okay? This is the closest value. That means, that means, pay attention and understand. That means, accuracy is nothing but it is the closest value of the correct value, which we also call degree of closeness. Does everyone understand what accuracy means? Accuracy is nothing but it is the closest value. Means, our original value. Suppose, for example, this is our, as I said, our scale. And this is also our scale. The correct value of this scale is 15 cm in length. But when I counted it, it came to 14.95 or 14.94. That is the approximate value. So, students, that is my accurate value in a way. Because 0.04 is very negligible. So this is our degree of closeness. Is it clear to everyone? Is everyone understanding? Quickly comment. Hello, I am talking to you. Comment. Yes. Is everyone understanding accurately? Is everyone understanding accurately? See students, these are short notes. I am telling you in a very good way. If you read the test book, you will not understand. You will not be able to read. Okay? Yes. Is it clear? Yes, yes, let's move on. Let's move on. Clear. Understand. Now students, see our accuracy is done. Now we have to go to the precision. Now what is mean by precision? I am telling you precision. Precision means students, I am next to you. Agal bagal wali value. Agal bagal wali value. Isko hum bolte hai degree of repeatability. Isko hum CET mein ya fir NEET JEE mein kya aayega? Accuracy ka aur ek naam kya hai? Lala log, lali log, it is nothing but it is the degree of closeness. But agar mai precision ki baat karu to precision ko hum kya kahenge It is the degree of repeatability. Ab yaap boluge bhaiya repeatability kya hota hai? See students, I am taking the same example again. Suppose for example, here also there is a scale and that is the same scale. Now the original value of that scale or the correct value is 15 cm. But students, my answer is coming next to it. Means who is next to 15? One will be 16, one will be 14, or 13 or 17. That means my this value is not coming. This value is not coming, but the next to it is coming. You will say that the next to it is also coming here, but the sample is very close. Here 14.9 something was close. What I am saying is that 14 is coming there. There is a difference of ground and sky between 14 and 14.9. There is a difference of ground and sky between 14 and 14.9. For example, I will tell you an example. Those children who have 90.40, 90.40% will be in 10th grade. That is 90% only. But those children who had 90.60% that is 91% Yes or no. Yes or no. That means this value of mine which I have written here this one is done in one way. To understand the example, I am writing precision here. And this degree of closeness which is very close to 91 what will I call that students? Accuracy. What is the difference? Did you understand the difference between accuracy and degree of closeness in precision? Yes. Did you understand the difference between accuracy and precision? Did you understand or not? Write it in chat. Yes or no. So, the values which are next to each other, we call them which is precision and precision is nothing but it is the repeatability. What does precision mean? repeatability repeatability we call it yes yes yes perfectly clear students aim for 100 likes quickly hit the like button we deserve 100 likes obviously on the main channel of state board 10-10 thousand likes come but this is a new channel we are trying to grow By the grace of God, your love will grow very fast with the help of support. We will pick up the silver play button of this very soon. We will have three silver play buttons. Okay, I am waiting for that moment. Yes, let's go. Now students, what is mean by uncertainty? Uncertainty means degree of sudden change. Real value is fake value. Means uncertainty has happened. Suppose for example, there is a huge difference. Suppose for example, there will be a sample. Suppose this is Lala. Do you know what Lala did? When his new wife, Lala, was new to him, when they were new, they used to love each other. When they were new, they used to love each other. Then students, Lala had taken a lot of oaths. And Lala also took a lot of oaths. We will be together for life. Okay, what do you say, towards eternity, I will break the moon and stars for you. Okay, promises, promises, everything was given. But, but, but, what happened after that? After that, students broke their inka in a few years. Okay, Lala Lala got a breakup. Means students, she was completely fake. Whatever he said earlier was fake. That's why I am giving you suggestions as elder brother. Whoever is listening to me, listen carefully. Listen carefully to what I am saying. The words I am telling you will change your life. Listen carefully, whoever's message makes you happy, block them. I am telling you this already. Whoever's message, meaning you are understanding about whom I am talking about. I am not talking about my parents, I am not talking about my friends. I am talking about that. If you got the message of Babu, Shona, Jadoo, Tona and you are happy, it is obvious that the time has come to block them. I am talking about the marks. I am not talking about anything else. I am talking about cutting the marks. Do you understand? So, you have to be sensible with that. Did you understand? Yes. Okay. Come on. Let's move forward, students. Let's move forward. Let's move forward. Okay. So, students, this is called uncertainty. Uncertainty means what we had hoped for. Okay. What we had hoped for. It didn't fall on the expectation. It was 15 cm and the answer is 2 cm. This is uncertainty. Did you understand? Accuracy means it is the closest. Degree of the closeness or closest. Precision means it is the degree of the repeatability. Whereas if we are talking about the uncertainty, it is the degree of sudden change. It changed suddenly. If there are any sudden changes in them, then they don't happen suddenly. There will be some reasons behind it and we call it errors. Similarly, students, in real life also no one changes suddenly, there are some patterns. If someone is changing in real life, then it is obvious that he had some patterns. There is no sudden change, no one changes suddenly, some things must have happened. There must be some reason, there must be some error, even if it is physical error, mental error, human error, anything. In the same way, students, when we do measurement in physics, we get some errors which we call uncertainty or errors. Errors means that something has gone wrong in the calculation. So, let's see what has gone wrong. So, till here, everyone understood. See it very well, students. By giving you examples of day-to-day life, I try to explain you in every lecture. So, brother, If you have understood, then write it in the chat. Yes, clear, clear, clear. Yes, yes, yes. Okay. Students, don't do 100 likes, do 100 likes quickly. Don't try to say this much. Fast and furious. Okay? Kids are watching above 110, hit the like button. Yes. Okay. Okay, one kid is saying and the other one is saying bad boy Why did my sister block me? As you wish, do the block You have taken this seriously You have to take it seriously Yes, you have to take it seriously Now students we are going to move into the errors in the measurement Now what usually mean errors? First of all, let's understand what error means. Faulty measurements of physical quantity can lead to errors. Faulty measurements can lead to errors. For example, if I have a scale. If I am told to make a base of 5 cm. If I take it from 0, it will be 5 cm. If I take it from 1, it will be 5 cm. Yes or no? So that means physical quantity when we take any faulty measurements we do something wrong. For example Optical angle is above 90 but I took it below 90 considering it as an acute angle. So it is nothing but it is the faulty measurements. Clear? It is nothing but it is the faulty measurements. Okay. Now There are various types of measurements. I am telling you about various types of measurements. Try to understand it properly. There are two types of measurements. What is the first one? The first one is the student's systematic error. This error occurs in only one direction i.e. positive or negative. This means that in systematic error, students can make only two types of errors. Or the error will be in only one direction. One will be in the positive direction and the other will be in the negative direction. First, what could be the reason for systematic error? What could be the reason for systematic error? First of all, imperfection in the technique. Meaning, whatever experiment you are doing, suppose you are told to use vernier caliper or screw gauze, but you are not the perfect person to take that particular experiment forward. Means you are not the perfect one to do that particular experiment. In that particular case, you will bring some imperfection in that particular case. Did you understand? Okay, suppose for example, if I am a teacher, that means my job is to teach you. Correct? If someone tells me, no, no, you go and do construction work. First time when I will do that work, it is obvious that I will be imperfect. So the first thing which causes the error is nothing but it is the imperfection in the techniques or in the experiment. Clear? I hope this is clear. Second one. Second one is like this, the error can be caused by the temperature, by the wind speed or by the humidity. Suppose for example, if I am doing some sort of experiment here. Right? I am experimenting. Now what happened students? In my experiment, the temperature that I need is room temperature. Room temperature is nothing but 25 degrees to 27 degrees Celsius. That's my guess. But what happened suddenly? I got a lot of heat in my room. I am giving an example. So the experiment that I had to do on room temperature, its temperature increases, so the values will also change. For example, if we are taking values on standard temperature and pressure, then how much should we take? How much value of STP did I say? According to the new test book, I had taught in chemistry. Tell me quickly, who remembers? According to the new test book, tell me the value of standard temperature and pressure. fast fast fast standard temperature and pressure value say it say it guys say it say it fast yes which is good that is 22.7 very good ok how much is it? 22.7 according to the new test book. According to the new test book. Very good. So, if you take some other value instead of standard temperature and pressure, then it will be wrong. If you take 22. something, then it will be different. Right? So we call that error. Did you understand till here? The third one is the personal error because of casual behaviour. Suppose if you look here, Hey, look here, look here, hello. Suppose for example, I said that you have to conduct this experiment. You are conducting it but suddenly your crush enters. Suddenly your crush enters or your best friend enters. He is doing the same thing or your crush is... style, hairstyle, you are making. What you do? Experiment went wrong, we will see that. Okay, we will give life, we will see that. So what happens students, this is because of the personal error. Means that his behavior was very casual. Casual in the sense that it is fine, it happened, it did not happen. We call it personal error. Did you understand everything till here? Did you understand everything? Yes. So that means, did you understand the systematic error? Systematic error can be due to three reasons. One is that there is an imperfection in the technique. Or it is due to temperature, wind speed, humidity or it is due to personal error. Is it clear? Yes. Now students we will see random error. Now what does random error means? Now what does random error means? Errors which cannot be associated with a constant cause. Suppose for example this error can be randomly have any sign. Like see plus minus taken. Means see students what you always do in examination is you write correct answer behind. When you are doing calculation then behind your division answer comes correct. Comes in plus. But you write and write and minus. Or is it written as 3 and 6 here? Does it happen or not? It must have happened with everyone. So, this is called as random error. Now, listen carefully. All the errors that I have told, all the errors that I have told, can be reduced. Now, how can it be reduced? After observing them many times, like for example students, see, I am giving an example. Okay, I am giving an example. Suppose if someone is bothering you, then you observe him first. What do you think for the first time? That he must have done it intentionally. Right? So this was the first error. Now he bothered you, you sat quietly for the first day. The next day came, he bothered you again. You observed him now. Means you observed him twice. The third time that person has come back to you, you have to bother him again. Or he is hitting you or whatever it is, he is making fun of you. He is making fun of you many times in the friend circle. You are observing that particular person. And the more you observe, the more you can push him that if you have done this after this, then see. I will complain or whatever it is, I will say something. So that means, what does it mean? The more you observe, the less error you will get. Understood? The more you observe, the less error you will get. So always keep in mind that observation is inversely proportional to random error. That means the more you observe, the less random error you will get. Did everyone understand till here? Yes or No? fast fast fast say fast fast because after this we are solving numericals after this we are solving numericals ok our topic is on last last stage on last last stage Now understand properly Now students if we have to count the errors Now if we have to count the errors Then we can count it in four ways Please understand properly students Hello, look here First is mean error First is nothing but it is the mean error Now you will say what is mean error Look properly Which one will be the first one? Write in the chat, all the kids. You also have to solve it. Which is mean error. Okay, now it is numerical. Now you will say that what is mean error? First of all mean error means average. Ok, find the average. Find the average of anything. How to find the average? See I am giving you the formula. Write like this in the formula. A mean equals to A plus A2 plus A3 plus dot dot dot plus An upon n. This is nothing but This is the formula. Okay. What is this? This is our formula. Now, you will say, Brother, throw an example in front of us. Look. Suppose, I am taking an example. If students, whenever you have done observation, suppose, you have done observation 4 times, then the value of A came 20 cm. The value of A2 came 21 cm. A3's value is 22.5 cm and A4's value is 26.5 cm. These are the given values. And if you get a question that take out A mean, then what will you do? You will write A mean. How many are there? There are 4 observations. So A plus A2 plus A3 plus A4. Correct. Okay. How many observations are there? 4. So division will be 4. If here A5 would have been, then we would have done it from 5. Do you understand? Okay. How much is A? 20 plus 21 plus 22.5 plus 26.5. Tell me how much is the addition of all these? 20 plus 21 is 41. 41 plus 22. I guess it is 90. Yes. How much will this be? 90. 90 by 4. Now what you have to do is simply divide 90 by 4. 4 times 1 is 4, 4 times 2 is 8, 0 is left, 1 is left is 10, 4 times 2 is again 8, again 2 is left. What is wrong? If you put 0 here, then you put a point here, 4 times 5 is 20, then what will be the answer? So the value of A mean came, A mean came, 22.5, all were in centimeters, so centimeters. What did you understand? How did you find the mean error? Okay? This is nothing but this is the mean error. Okay? This is how we found the mean error. Yes? This is how we found the mean error. Did everyone understand the mean error? Yes or no? Let me know. Did everyone understand the mean error? Okay, clear clear clear Write in the chat once fast and furious Yes, okay The second one students will be absolute mean See we have done the first one. Now mean absolute error. What will happen in the second one? Mean absolute error. Students please pay attention. Mean absolute error. Now students, what we show this or I will write a formula directly for this. We show this as delta A mean. What is this called? Delta A mean. See, what will come in bracket? Mod of A mean minus A plus mod of A mean minus A2 plus dot dot dot mod of A mean minus an upon will come your n. Means, whatever number you have written. See, now you will say, how? See, did everyone understand the formula well? Did everyone understand the formula? Okay, in this formula, students, always keep one thing in mind. If you came to find mean absolute error, then see. Here, students, what is A mean? Means you have to find A mean first. Means you have to find A mean first. In order to find mean absolute error, you first have to find A mean. So now let's do one thing. We take the same question here and we keep the value of A mean here. Did you understand? We keep the value of A mean here. Suppose let's do one thing, let's take a new sum. Look, question. Suppose I have taken A as 20, A2 as 30 and A3 as 40. These are nothing but these are the centimeters. This is the question that we have to solve. And you have to find mean absolute error. You have to find mean absolute error. Now understand this properly. First of all, the first thing that you have to do is you have to find the A mean. Why? Because here is A mean. So how will you find A mean? A plus A2 plus A3 upon 3. So, say then, what will you get? 20 plus 30 plus 40 upon 3. So, this will be 20 plus 30, 50. 50 plus 40, 90. 90 upon 3. That means, what did Ameen get? 90 upon 3. 3 1, 3 3. So, that means... How much did A-min get? Then 3 cm. Yes or no? Yes or no? Yes or no? Yes or no? Yes, I got it. Okay, I understood till here. Okay, this was like the previous one. But, students, what we have to find now is delta A-min. So, what is delta A-min? Which is the value of A-min. First, minus A and then add plus. Then again, A-minus A2. Then again, A-minus A3. What is everyone understanding? Upon n. n means 3. Now students, it is mod. Whatever is in minus in mod, it becomes plus outside. Okay. So see what will we get in A-minus. A-minus is 3. A-minus is 20. So 3-20. 3-30 mod plus 3-30 mod plus 3-40 mod 3-20 mod plus 3-40 mod plus 3-40 mod plus 3-40 mod 3-40 mod plus 3-40 mod plus 3-40 mod Calculate this. How much is this? 17 plus 27 plus 37 Can you understand? This is nothing but 81 upon 3 I guess 81 upon 3 is 27 Or else Yes 27 So what will be the answer? Delta aiming will be 27 cm. Do you understand? If you want to cross check it, you can do it. How can you cross check it? You can multiply the value and the number of n you have given. You can cross check it. So the answer is correct. 3 to the cube is 27. Sorry, I am saying 3 to the cube. If we did 3 to the triple bar, which was n, then we got 27. What did you understand? Let me know in the chats, fast I am telling you in a very simple way Nobody will tell you in such a simple way I am very tired sir Let's do one thing We have done the calculation Let's do one thing Let's cut from all sides 0-0 You are getting very fast. But then it will be wrong here. Let's change this. Let's change this. 3-2 I know what is this. I didn't see your comments. I solved it in flow. Okay, I solved it in flow flow. 3-2, how much is 3-3? It will be 0 and this is 3-4. So that means 1 plus 0 plus 1 so answer will be 2 by 3 ok answer will be 2 by 3 so that will be approximately 0.666 which we can write approximately 0.67 cm what did you understand? ok now it will be clear ok now it will be clear yes Okay students, I am giving you all a homework. Okay, let's do one thing, first we will solve one more. And one more means after this. Now we will see students relative error. First we saw mean error, then mean absolute error. Now we will see relative error. Are you ready everyone? Okay, did everyone understand both? Okay. Mean error formula is understood. Mean absolute is also understood. Okay. Now students we will understand relative error. See students relative error is the simplest. Relative error is the simplest. You will say how? Relative error. The third one is nothing but. It is relative. Error. Okay. What is the third one? Relative error. Relative error is written as it is. Means there is no such symbol given. What is relative error? Look at the formula. Delta A mean upon A mean. Okay. Means the delta A mean value we got, you have to divide it by A mean. Delta A mean is 0.67 My brother wrote 0.67 A mean is 3 Do you understand? If we calculate it Approximate value will be 0.22 something Is it? If it is 0.67, if it is 0.67 from 3, if it is dividing from 3, then it will be 0.22 something. Do you understand? Do you understand? Yes or no? Yes or no? Okay. And the last one is, students, the last one is percentage error. The last one is percentage error. So, what you have to do is, the relative error formula that has been given, the answer of the relative error, you have to apply percentage before that. What you have to do before that is, you have to apply percentage before that. That's it. Clear? Yes, yes, yes. Means what we have to do is multiply it by 100. Okay. For example, 0.22 is there. Into 100. We always know in percentage that we do it by 100. So, if we move 2 points ahead, then how much will it be? 22%. Did you understand? How much percent? 22%. Yes. Yes, yes, yes, Divyani, 22%. Okay, let's do one thing, students. Let's try to solve all together one last time. Okay? Let's take all values and try to solve them together. Let's see if we get the answer or not. Clear. Okay? We will remove all. Relative error. Sorry, mean. Then absolute mean. Then relative and percentage. yes yes okay so the question I am giving you suppose for example a1 okay even even I have given suppose 26 a2 I have given 28 a3 I have given 32 and a4 which is 28 32 A2 is 28, A3 is 32 and A4 is 34. We have to find all of them. First of all we will find mean error. First of all we are going to solve mean error. So what is the formula? A mean equals to A. plus a2 plus a3 plus a4 upon 4 which is 26 plus 28 plus 32 plus 34. Tell me, I want to give you the answer quickly. Tell me, 26 plus 28 plus 32 plus 34 upon how much is 4? So, I guess it is 120 upon 4. So, how much aiming did I get? 120 upon 4. 4 1 sub 4, 4 3 sub 12. I will not do it wrong now. So, how much aiming did I get? 30 centimeter. Yes, how much did I get? 30 centimeter. How is the vision aligned? How is the vision aligned? 30 centimeter. Come on, very good brother. Come on, I have understood till here. Okay, we have understood it very well. Okay, moving on to the second. What is the second one? Which is absolute mean error. We all know its formula. Delta absolute mean. So, let's do one thing, let's write it directly. How much is it? 30 minus First is 26, so 30 minus 26 plus 30 minus 28 plus 30 minus 30 plus 30 minus 34. All are in mod, upon 4, so therefore delta A mean, how much was it? 4 plus 2 plus 0. plus both have difference of 4 plus 4 upon 4 not equal 4 plus 2 is 6 6 plus 4 10 upon 4 so how can we write 10 upon 4 5 by 2 which is 2.5 cm yes I am doing it right ok so delta A mean how much is it 2.5 yes delta E min is 2.30-32 oh got it got it got it See, I told you, something happens in flow. 30 minus 32, good, I saw the comment. So again 2 plus 4. Yes, 2 plus 4. Now it is clear, what was its name? Babu boy. Yes. So how much is this? 4 plus 2, 6. 6 plus 2, 8. 8 plus 2, 12. So, answer will be 3. Answer will be 3. Clear? Answer is 3. Okay. Now, relative. Now, what will be relative? So, what is relative? Relative error, delta A mean upon a mean. So how much will it be? 3 upon 30. Okay. So see how I can write this. 3 upon 3 into 10 raised to 1. 10 raised to 1 went up. Means 3 into 10 raised to minus 1 upon 3. So this got cut. So 1 is left. Means how much came? 0.1 came. Who to whom to explain? See what happened? 3 upon 30 was there. So let 3 remain as it is. How did I write this 30? 3 into 10 raised to 1. Now this 10 raised to 1 went up. So how much is 10 raised to minus 1 upon 3? 3 3 cut 1 is done. Means the answer is 1 into 10 raised to minus 1. So 1 into 10 raised to minus 1 I can write 0.1. Yes, now I have to find the percentage of the sun. Now I have to find the percentage. So what percentage will I do? 0.1 x 100 which will be 10%. How much percent? 10%. Yes, which will be 10%. Come on, come on, come on. Say clear, fast and furious. Yes. Clear? So students, I hope this particular lecture you have understood well. And students, here I declare that the chapter is over. Tomorrow we will start a new chapter of physics. You will see the thumbnail of the chapter tomorrow morning at 12 o'clock. Okay, quickly say bye to me. Come on, say bye to me. Sir, where I can refer extra numericals for physics? In your test book or solved examples. Okay, solve examples and then do it in your test book. Students, you will get its PDF today itself on your Telegram group. So, quickly download the Telegram group. What is download? I have given the link in the description. I have given Telegram, Instagram and Snapchat. wherever you can follow me, do it because i guess that in the coming time many things are going to happen to you yes, we will take the lock table one day we will see one or two days of sunday we will see one or two days of sunday Now students listen, whatever is being said about dimensions, listen carefully. The dimensions that will be given to you in the test book, 9 dimensions will be given to you in the quantities of 9 to 10, which is in the physics test book, learn that much. In 12th, students, as soon as we start the first chapter of 12th, Rotational Dynamics of 12th, then I will teach you the dimensions in full detail. For now, please focus on what I am teaching and learn the dimensions. If you have understood this much in this chapter, then it is a very good thing. Your basics of physics have been cleared. I hope students you get all the points that I have told you. Don't worry, nothing will be skipped. Think about everything. I have not even taught the dimensions in my offline. We will teach it in January. Yes. Let's go. So, see you students tomorrow. Till then keep on making fun of me. See, we have completed 3 chapters while talking. 2 of chemistry and 1 of physics. Okay. Consistency matters and maybe someone will have consistency like me. Okay. And you will also have to give a scolding. Okay. Bye. See you.

Then we discussed some things about parallax method. We saw 3 types of parallax method. First one was measurement of distance of the stars or planet and also the size of the planet. After that we have witnessed about the very small distances which I told you yesterday in one point. The very small atoms and molecules, the very fine things We can't see it with vernier caliper or screen gauge For that we need electron microscope or tunneling electron microscope Okay?

Yes? Clear? Okay! Okay! Now students pay attention, what we are going to start today By the way, did everyone completed DPP yesterday?

Yes everyone, did everyone completed DPP yesterday? Tell me in comments Because students, yesterday I told you that this is what you have to learn on the yesterday basis. Before the session ends, brother had told you to do these things. Hello, pay attention. Don't look here and there.

Don't sit and comment. Don't talk about here and there. I am talking to you. Look properly.

Okay. Important things are going on. One is the value of astronomical unit, light year, per sec, par sec.

Okay. Each and everything brother explained to you in detail yesterday. I hope you all have done it.

Like it quickly. Let's aim for 100 plus likes. Okay. Now students, what we are going to identify today or what we are going to see today is Accuracy, Precision, Uncertainty in the measurements. Means students, we are going to see three things today.

And above this, above the errors, We will solve some numericals also. So, all students please take your book and pen. I will tell you in a very simple way. First of all, we will see what is mean by accuracy. For example, your brother used to say that these questions are possible to come in paper and there are chances to come in paper.

So, obviously, the same type of questions used to come in paper. Obviously, they will not come completely because we do not make paper at home. But, Closest value used to come.

Yes or no? You have to believe that your 10th brother has taken it out. Hahaha. Okay. So that means students, So accuracy is nothing but it is the closest value of the correct value.

Suppose for example students, this is a particular scale. See this example properly. Okay. And this is also a scale. Now the actual value of this scale or the correct value of this scale.

Okay. What is the correct value? 15 cm.

But when I measured it, it was 14.95, 14.94 or 14.93. That means it is closest value. Yes or no?

Is it closest or not? See students, we can write 14.95 as 15.00. Why can we write? Because this is the closest value.

Okay? This is the closest value. That means, that means, pay attention and understand.

That means, accuracy is nothing but it is the closest value of the correct value, which we also call degree of closeness. Does everyone understand what accuracy means? Accuracy is nothing but it is the closest value. Means, our original value. Suppose, for example, this is our, as I said, our scale.

And this is also our scale. The correct value of this scale is 15 cm in length. But when I counted it, it came to 14.95 or 14.94. That is the approximate value. So, students, that is my accurate value in a way.

Because 0.04 is very negligible. So this is our degree of closeness. Is it clear to everyone? Is everyone understanding? Quickly comment.

Hello, I am talking to you. Comment. Yes.

Is everyone understanding accurately? Is everyone understanding accurately? See students, these are short notes.

I am telling you in a very good way. If you read the test book, you will not understand. You will not be able to read. Okay?

Yes. Is it clear? Yes, yes, let's move on.

Let's move on. Clear. Understand.

Now students, see our accuracy is done. Now we have to go to the precision. Now what is mean by precision?

I am telling you precision. Precision means students, I am next to you. Agal bagal wali value.

Agal bagal wali value. Isko hum bolte hai degree of repeatability. Isko hum CET mein ya fir NEET JEE mein kya aayega?

Accuracy ka aur ek naam kya hai? Lala log, lali log, it is nothing but it is the degree of closeness. But agar mai precision ki baat karu to precision ko hum kya kahenge It is the degree of repeatability.

Ab yaap boluge bhaiya repeatability kya hota hai? See students, I am taking the same example again. Suppose for example, here also there is a scale and that is the same scale.

Now the original value of that scale or the correct value is 15 cm. But students, my answer is coming next to it. Means who is next to 15?

One will be 16, one will be 14, or 13 or 17. That means my this value is not coming. This value is not coming, but the next to it is coming. You will say that the next to it is also coming here, but the sample is very close.

Here 14.9 something was close. What I am saying is that 14 is coming there. There is a difference of ground and sky between 14 and 14.9.

There is a difference of ground and sky between 14 and 14.9. For example, I will tell you an example. Those children who have 90.40, 90.40% will be in 10th grade. That is 90% only.

But those children who had 90.60% that is 91% Yes or no. Yes or no. That means this value of mine which I have written here this one is done in one way.

To understand the example, I am writing precision here. And this degree of closeness which is very close to 91 what will I call that students? Accuracy.

What is the difference? Did you understand the difference between accuracy and degree of closeness in precision? Yes. Did you understand the difference between accuracy and precision? Did you understand or not?

Write it in chat. Yes or no. So, the values which are next to each other, we call them which is precision and precision is nothing but it is the repeatability. What does precision mean?

repeatability repeatability we call it yes yes yes perfectly clear students aim for 100 likes quickly hit the like button we deserve 100 likes obviously on the main channel of state board 10-10 thousand likes come but this is a new channel we are trying to grow By the grace of God, your love will grow very fast with the help of support. We will pick up the silver play button of this very soon. We will have three silver play buttons. Okay, I am waiting for that moment. Yes, let's go.

Now students, what is mean by uncertainty? Uncertainty means degree of sudden change. Real value is fake value. Means uncertainty has happened. Suppose for example, there is a huge difference.

Suppose for example, there will be a sample. Suppose this is Lala. Do you know what Lala did?

When his new wife, Lala, was new to him, when they were new, they used to love each other. When they were new, they used to love each other. Then students, Lala had taken a lot of oaths.

And Lala also took a lot of oaths. We will be together for life. Okay, what do you say, towards eternity, I will break the moon and stars for you.

Okay, promises, promises, everything was given. But, but, but, what happened after that? After that, students broke their inka in a few years.

Okay, Lala Lala got a breakup. Means students, she was completely fake. Whatever he said earlier was fake.

That's why I am giving you suggestions as elder brother. Whoever is listening to me, listen carefully. Listen carefully to what I am saying.

The words I am telling you will change your life. Listen carefully, whoever's message makes you happy, block them. I am telling you this already.

Whoever's message, meaning you are understanding about whom I am talking about. I am not talking about my parents, I am not talking about my friends. I am talking about that.

If you got the message of Babu, Shona, Jadoo, Tona and you are happy, it is obvious that the time has come to block them. I am talking about the marks. I am not talking about anything else.

I am talking about cutting the marks. Do you understand? So, you have to be sensible with that.

Did you understand? Yes. Okay.

Come on. Let's move forward, students. Let's move forward. Let's move forward.

Okay. So, students, this is called uncertainty. Uncertainty means what we had hoped for. Okay. What we had hoped for.

It didn't fall on the expectation. It was 15 cm and the answer is 2 cm. This is uncertainty. Did you understand? Accuracy means it is the closest.

Degree of the closeness or closest. Precision means it is the degree of the repeatability. Whereas if we are talking about the uncertainty, it is the degree of sudden change. It changed suddenly.

If there are any sudden changes in them, then they don't happen suddenly. There will be some reasons behind it and we call it errors. Similarly, students, in real life also no one changes suddenly, there are some patterns.

If someone is changing in real life, then it is obvious that he had some patterns. There is no sudden change, no one changes suddenly, some things must have happened. There must be some reason, there must be some error, even if it is physical error, mental error, human error, anything. In the same way, students, when we do measurement in physics, we get some errors which we call uncertainty or errors.

Errors means that something has gone wrong in the calculation. So, let's see what has gone wrong. So, till here, everyone understood.

See it very well, students. By giving you examples of day-to-day life, I try to explain you in every lecture. So, brother, If you have understood, then write it in the chat. Yes, clear, clear, clear. Yes, yes, yes.

Okay. Students, don't do 100 likes, do 100 likes quickly. Don't try to say this much. Fast and furious.

Okay? Kids are watching above 110, hit the like button. Yes. Okay.

Okay, one kid is saying and the other one is saying bad boy Why did my sister block me? As you wish, do the block You have taken this seriously You have to take it seriously Yes, you have to take it seriously Now students we are going to move into the errors in the measurement Now what usually mean errors? First of all, let's understand what error means.

Faulty measurements of physical quantity can lead to errors. Faulty measurements can lead to errors. For example, if I have a scale.

If I am told to make a base of 5 cm. If I take it from 0, it will be 5 cm. If I take it from 1, it will be 5 cm.

Yes or no? So that means physical quantity when we take any faulty measurements we do something wrong. For example Optical angle is above 90 but I took it below 90 considering it as an acute angle. So it is nothing but it is the faulty measurements. Clear?

It is nothing but it is the faulty measurements. Okay. Now There are various types of measurements.

I am telling you about various types of measurements. Try to understand it properly. There are two types of measurements. What is the first one?

The first one is the student's systematic error. This error occurs in only one direction i.e. positive or negative. This means that in systematic error, students can make only two types of errors.

Or the error will be in only one direction. One will be in the positive direction and the other will be in the negative direction. First, what could be the reason for systematic error?

What could be the reason for systematic error? First of all, imperfection in the technique. Meaning, whatever experiment you are doing, suppose you are told to use vernier caliper or screw gauze, but you are not the perfect person to take that particular experiment forward.

Means you are not the perfect one to do that particular experiment. In that particular case, you will bring some imperfection in that particular case. Did you understand?

Okay, suppose for example, if I am a teacher, that means my job is to teach you. Correct? If someone tells me, no, no, you go and do construction work. First time when I will do that work, it is obvious that I will be imperfect.

So the first thing which causes the error is nothing but it is the imperfection in the techniques or in the experiment. Clear? I hope this is clear. Second one. Second one is like this, the error can be caused by the temperature, by the wind speed or by the humidity.

Suppose for example, if I am doing some sort of experiment here. Right? I am experimenting.

Now what happened students? In my experiment, the temperature that I need is room temperature. Room temperature is nothing but 25 degrees to 27 degrees Celsius. That's my guess.

But what happened suddenly? I got a lot of heat in my room. I am giving an example.

So the experiment that I had to do on room temperature, its temperature increases, so the values will also change. For example, if we are taking values on standard temperature and pressure, then how much should we take? How much value of STP did I say?

According to the new test book, I had taught in chemistry. Tell me quickly, who remembers? According to the new test book, tell me the value of standard temperature and pressure.

fast fast fast standard temperature and pressure value say it say it guys say it say it fast yes which is good that is 22.7 very good ok how much is it? 22.7 according to the new test book. According to the new test book. Very good.

So, if you take some other value instead of standard temperature and pressure, then it will be wrong. If you take 22. something, then it will be different. Right?

So we call that error. Did you understand till here? The third one is the personal error because of casual behaviour. Suppose if you look here, Hey, look here, look here, hello.

Suppose for example, I said that you have to conduct this experiment. You are conducting it but suddenly your crush enters. Suddenly your crush enters or your best friend enters. He is doing the same thing or your crush is... style, hairstyle, you are making.

What you do? Experiment went wrong, we will see that. Okay, we will give life, we will see that.

So what happens students, this is because of the personal error. Means that his behavior was very casual. Casual in the sense that it is fine, it happened, it did not happen. We call it personal error.

Did you understand everything till here? Did you understand everything? Yes.

So that means, did you understand the systematic error? Systematic error can be due to three reasons. One is that there is an imperfection in the technique.

Or it is due to temperature, wind speed, humidity or it is due to personal error. Is it clear? Yes. Now students we will see random error.

Now what does random error means? Now what does random error means? Errors which cannot be associated with a constant cause. Suppose for example this error can be randomly have any sign. Like see plus minus taken.

Means see students what you always do in examination is you write correct answer behind. When you are doing calculation then behind your division answer comes correct. Comes in plus. But you write and write and minus.

Or is it written as 3 and 6 here? Does it happen or not? It must have happened with everyone. So, this is called as random error. Now, listen carefully.

All the errors that I have told, all the errors that I have told, can be reduced. Now, how can it be reduced? After observing them many times, like for example students, see, I am giving an example. Okay, I am giving an example.

Suppose if someone is bothering you, then you observe him first. What do you think for the first time? That he must have done it intentionally.

Right? So this was the first error. Now he bothered you, you sat quietly for the first day.

The next day came, he bothered you again. You observed him now. Means you observed him twice. The third time that person has come back to you, you have to bother him again. Or he is hitting you or whatever it is, he is making fun of you.

He is making fun of you many times in the friend circle. You are observing that particular person. And the more you observe, the more you can push him that if you have done this after this, then see.

I will complain or whatever it is, I will say something. So that means, what does it mean? The more you observe, the less error you will get.

Understood? The more you observe, the less error you will get. So always keep in mind that observation is inversely proportional to random error.

That means the more you observe, the less random error you will get. Did everyone understand till here? Yes or No? fast fast fast say fast fast because after this we are solving numericals after this we are solving numericals ok our topic is on last last stage on last last stage Now understand properly Now students if we have to count the errors Now if we have to count the errors Then we can count it in four ways Please understand properly students Hello, look here First is mean error First is nothing but it is the mean error Now you will say what is mean error Look properly Which one will be the first one?

Write in the chat, all the kids. You also have to solve it. Which is mean error. Okay, now it is numerical.

Now you will say that what is mean error? First of all mean error means average. Ok, find the average.

Find the average of anything. How to find the average? See I am giving you the formula.

Write like this in the formula. A mean equals to A plus A2 plus A3 plus dot dot dot plus An upon n. This is nothing but This is the formula.

Okay. What is this? This is our formula.

Now, you will say, Brother, throw an example in front of us. Look. Suppose, I am taking an example. If students, whenever you have done observation, suppose, you have done observation 4 times, then the value of A came 20 cm.

The value of A2 came 21 cm. A3's value is 22.5 cm and A4's value is 26.5 cm. These are the given values. And if you get a question that take out A mean, then what will you do? You will write A mean.

How many are there? There are 4 observations. So A plus A2 plus A3 plus A4.

Correct. Okay. How many observations are there? 4. So division will be 4. If here A5 would have been, then we would have done it from 5. Do you understand?

Okay. How much is A? 20 plus 21 plus 22.5 plus 26.5. Tell me how much is the addition of all these?

20 plus 21 is 41. 41 plus 22. I guess it is 90. Yes. How much will this be? 90. 90 by 4. Now what you have to do is simply divide 90 by 4. 4 times 1 is 4, 4 times 2 is 8, 0 is left, 1 is left is 10, 4 times 2 is again 8, again 2 is left.

What is wrong? If you put 0 here, then you put a point here, 4 times 5 is 20, then what will be the answer? So the value of A mean came, A mean came, 22.5, all were in centimeters, so centimeters.

What did you understand? How did you find the mean error? Okay?

This is nothing but this is the mean error. Okay? This is how we found the mean error. Yes?

This is how we found the mean error. Did everyone understand the mean error? Yes or no?

Let me know. Did everyone understand the mean error? Okay, clear clear clear Write in the chat once fast and furious Yes, okay The second one students will be absolute mean See we have done the first one.

Now mean absolute error. What will happen in the second one? Mean absolute error.

Students please pay attention. Mean absolute error. Now students, what we show this or I will write a formula directly for this. We show this as delta A mean.

What is this called? Delta A mean. See, what will come in bracket?

Mod of A mean minus A plus mod of A mean minus A2 plus dot dot dot mod of A mean minus an upon will come your n. Means, whatever number you have written. See, now you will say, how?

See, did everyone understand the formula well? Did everyone understand the formula? Okay, in this formula, students, always keep one thing in mind. If you came to find mean absolute error, then see.

Here, students, what is A mean? Means you have to find A mean first. Means you have to find A mean first. In order to find mean absolute error, you first have to find A mean. So now let's do one thing.

We take the same question here and we keep the value of A mean here. Did you understand? We keep the value of A mean here. Suppose let's do one thing, let's take a new sum. Look, question.

Suppose I have taken A as 20, A2 as 30 and A3 as 40. These are nothing but these are the centimeters. This is the question that we have to solve. And you have to find mean absolute error. You have to find mean absolute error. Now understand this properly.

First of all, the first thing that you have to do is you have to find the A mean. Why? Because here is A mean. So how will you find A mean? A plus A2 plus A3 upon 3. So, say then, what will you get?

20 plus 30 plus 40 upon 3. So, this will be 20 plus 30, 50. 50 plus 40, 90. 90 upon 3. That means, what did Ameen get? 90 upon 3. 3 1, 3 3. So, that means... How much did A-min get?

Then 3 cm. Yes or no? Yes or no? Yes or no?

Yes or no? Yes, I got it. Okay, I understood till here. Okay, this was like the previous one. But, students, what we have to find now is delta A-min.

So, what is delta A-min? Which is the value of A-min. First, minus A and then add plus. Then again, A-minus A2. Then again, A-minus A3.

What is everyone understanding? Upon n. n means 3. Now students, it is mod.

Whatever is in minus in mod, it becomes plus outside. Okay. So see what will we get in A-minus.

A-minus is 3. A-minus is 20. So 3-20. 3-30 mod plus 3-30 mod plus 3-40 mod 3-20 mod plus 3-40 mod plus 3-40 mod plus 3-40 mod 3-40 mod plus 3-40 mod plus 3-40 mod Calculate this. How much is this?

17 plus 27 plus 37 Can you understand? This is nothing but 81 upon 3 I guess 81 upon 3 is 27 Or else Yes 27 So what will be the answer? Delta aiming will be 27 cm.

Do you understand? If you want to cross check it, you can do it. How can you cross check it? You can multiply the value and the number of n you have given.

You can cross check it. So the answer is correct. 3 to the cube is 27. Sorry, I am saying 3 to the cube. If we did 3 to the triple bar, which was n, then we got 27. What did you understand?

Let me know in the chats, fast I am telling you in a very simple way Nobody will tell you in such a simple way I am very tired sir Let's do one thing We have done the calculation Let's do one thing Let's cut from all sides 0-0 You are getting very fast. But then it will be wrong here. Let's change this.

Let's change this. 3-2 I know what is this. I didn't see your comments.

I solved it in flow. Okay, I solved it in flow flow. 3-2, how much is 3-3? It will be 0 and this is 3-4. So that means 1 plus 0 plus 1 so answer will be 2 by 3 ok answer will be 2 by 3 so that will be approximately 0.666 which we can write approximately 0.67 cm what did you understand?

ok now it will be clear ok now it will be clear yes Okay students, I am giving you all a homework. Okay, let's do one thing, first we will solve one more. And one more means after this.

Now we will see students relative error. First we saw mean error, then mean absolute error. Now we will see relative error.

Are you ready everyone? Okay, did everyone understand both? Okay.

Mean error formula is understood. Mean absolute is also understood. Okay.

Now students we will understand relative error. See students relative error is the simplest. Relative error is the simplest.

You will say how? Relative error. The third one is nothing but. It is relative.

Error. Okay. What is the third one? Relative error. Relative error is written as it is.

Means there is no such symbol given. What is relative error? Look at the formula.

Delta A mean upon A mean. Okay. Means the delta A mean value we got, you have to divide it by A mean. Delta A mean is 0.67 My brother wrote 0.67 A mean is 3 Do you understand?

If we calculate it Approximate value will be 0.22 something Is it? If it is 0.67, if it is 0.67 from 3, if it is dividing from 3, then it will be 0.22 something. Do you understand?

Do you understand? Yes or no? Yes or no?

Okay. And the last one is, students, the last one is percentage error. The last one is percentage error. So, what you have to do is, the relative error formula that has been given, the answer of the relative error, you have to apply percentage before that. What you have to do before that is, you have to apply percentage before that.

That's it. Clear? Yes, yes, yes.

Means what we have to do is multiply it by 100. Okay. For example, 0.22 is there. Into 100. We always know in percentage that we do it by 100. So, if we move 2 points ahead, then how much will it be?

22%. Did you understand? How much percent? 22%. Yes.

Yes, yes, yes, Divyani, 22%. Okay, let's do one thing, students. Let's try to solve all together one last time. Okay?

Let's take all values and try to solve them together. Let's see if we get the answer or not. Clear. Okay? We will remove all.

Relative error. Sorry, mean. Then absolute mean. Then relative and percentage.

yes yes okay so the question I am giving you suppose for example a1 okay even even I have given suppose 26 a2 I have given 28 a3 I have given 32 and a4 which is 28 32 A2 is 28, A3 is 32 and A4 is 34. We have to find all of them. First of all we will find mean error. First of all we are going to solve mean error. So what is the formula?

A mean equals to A. plus a2 plus a3 plus a4 upon 4 which is 26 plus 28 plus 32 plus 34. Tell me, I want to give you the answer quickly. Tell me, 26 plus 28 plus 32 plus 34 upon how much is 4?

So, I guess it is 120 upon 4. So, how much aiming did I get? 120 upon 4. 4 1 sub 4, 4 3 sub 12. I will not do it wrong now. So, how much aiming did I get? 30 centimeter. Yes, how much did I get?

30 centimeter. How is the vision aligned? How is the vision aligned?

30 centimeter. Come on, very good brother. Come on, I have understood till here. Okay, we have understood it very well.

Okay, moving on to the second. What is the second one? Which is absolute mean error. We all know its formula.

Delta absolute mean. So, let's do one thing, let's write it directly. How much is it?

30 minus First is 26, so 30 minus 26 plus 30 minus 28 plus 30 minus 30 plus 30 minus 34. All are in mod, upon 4, so therefore delta A mean, how much was it? 4 plus 2 plus 0. plus both have difference of 4 plus 4 upon 4 not equal 4 plus 2 is 6 6 plus 4 10 upon 4 so how can we write 10 upon 4 5 by 2 which is 2.5 cm yes I am doing it right ok so delta A mean how much is it 2.5 yes delta E min is 2.30-32 oh got it got it got it See, I told you, something happens in flow. 30 minus 32, good, I saw the comment. So again 2 plus 4. Yes, 2 plus 4. Now it is clear, what was its name? Babu boy.

Yes. So how much is this? 4 plus 2, 6. 6 plus 2, 8. 8 plus 2, 12. So, answer will be 3. Answer will be 3. Clear?

Answer is 3. Okay. Now, relative. Now, what will be relative?

So, what is relative? Relative error, delta A mean upon a mean. So how much will it be?

3 upon 30. Okay. So see how I can write this. 3 upon 3 into 10 raised to 1. 10 raised to 1 went up. Means 3 into 10 raised to minus 1 upon 3. So this got cut.

So 1 is left. Means how much came? 0.1 came.

Who to whom to explain? See what happened? 3 upon 30 was there. So let 3 remain as it is. How did I write this 30?

3 into 10 raised to 1. Now this 10 raised to 1 went up. So how much is 10 raised to minus 1 upon 3? 3 3 cut 1 is done. Means the answer is 1 into 10 raised to minus 1. So 1 into 10 raised to minus 1 I can write 0.1. Yes, now I have to find the percentage of the sun.

Now I have to find the percentage. So what percentage will I do? 0.1 x 100 which will be 10%. How much percent? 10%.

Yes, which will be 10%. Come on, come on, come on. Say clear, fast and furious.

Yes. Clear? So students, I hope this particular lecture you have understood well. And students, here I declare that the chapter is over. Tomorrow we will start a new chapter of physics.

You will see the thumbnail of the chapter tomorrow morning at 12 o'clock. Okay, quickly say bye to me. Come on, say bye to me.

Sir, where I can refer extra numericals for physics? In your test book or solved examples. Okay, solve examples and then do it in your test book. Students, you will get its PDF today itself on your Telegram group.

So, quickly download the Telegram group. What is download? I have given the link in the description. I have given Telegram, Instagram and Snapchat. wherever you can follow me, do it because i guess that in the coming time many things are going to happen to you yes, we will take the lock table one day we will see one or two days of sunday we will see one or two days of sunday Now students listen, whatever is being said about dimensions, listen carefully.

The dimensions that will be given to you in the test book, 9 dimensions will be given to you in the quantities of 9 to 10, which is in the physics test book, learn that much. In 12th, students, as soon as we start the first chapter of 12th, Rotational Dynamics of 12th, then I will teach you the dimensions in full detail. For now, please focus on what I am teaching and learn the dimensions. If you have understood this much in this chapter, then it is a very good thing.

Your basics of physics have been cleared. I hope students you get all the points that I have told you. Don't worry, nothing will be skipped. Think about everything.

I have not even taught the dimensions in my offline. We will teach it in January. Yes.

Let's go. So, see you students tomorrow. Till then keep on making fun of me. See, we have completed 3 chapters while talking. 2 of chemistry and 1 of physics.

Okay. Consistency matters and maybe someone will have consistency like me. Okay.

And you will also have to give a scolding. Okay. Bye. See you.

Transcript for:Understanding Units and Measurement Concepts

Transcript for:
Understanding Units and Measurement Concepts