 Write down transistor as an amplifier Okay, so you can see that there is a relation for input voltage. Okay, so if I Again, write this down vi is Vbe Plus Ibrb Then what is delta vi what it should be equal to? How much is delta Vbe first? Tell me what is Vbe be Vbe is the bearer potential Yes or no There you go look at this Vbe you're going from base to emitter. This one is a bearer potential Vbe Okay, now will bearer potential change if you change the input voltage It it remains in the forward bias. It will be more or less close to 0.7 volt only Okay, so Vbe will not change if you change input voltage Delta Vbe will be zero. So Delta vi will be equal to Delta Ib into Rb. Okay, so this is your first relation Let's say third relation first and two are there Okay, now similarly What is Delta V o? Delta V o if you see whenever we talk about amplification We keep the output voltage source if there is any voltage source out at output side to be constant So Delta Vcc will become zero Okay, so this will be minus of Delta ic Rc this is equation number four okay, so you have Voltage amplification which is represented as capital a with subscript V as Delta V o divided by Delta vi All right, this is equal to minus of Delta ic by Delta Ib Into Rc by Rb. Okay. Now Delta ic by Delta Ib is beta ic. So this is beta ic times Rc by Rb. Okay, so you can just vary the resistances Rc and Rb and You'll get different values for Av Fine. So is this thing clear transistor as an amplifier and transistor as a switch Any doubts? No, sir Those who are watching from YouTube. Do you have any doubts? Somebody said something. No doubt guys. No, those who are online All right So this is it. I mean with respect to transistor We will now talk about The most easy part of this chapter and we are at the fag end of this Semiconductor's chapter. So So what are we doing after this chapter today? That will discuss after the chapter I have Okay, all right, so write down logic gates logic gates See when you were kids you have learned numbers one two three four five six, right? My daughter has learned up to 30 now It's four four and a half year old. Anyway, the numbers Yes, so you have learned Numbers or just counting using numbers, okay But the actual usage of number will happen when you learn how to add how to multiply how to divide Okay, then only you will be able to do some operations on it Getting it similarly when you will learn about digital electronics Okay, you will understand that Essentially the message has to get transmitted as a sequence of zeros and ones Okay, so a particular sequence of zero and one could mean a letter a Then another sequence could mean letter B Then a particular sequence could mean color yellow color could could mean green color like that They can be coding done by zero and one. Okay. One thing is doing Encoding a particular thing as a sequence of zero and one but another more important thing is You know doing some sort of operations on it as in you As in what I mean to say is that How to process the data Okay, in order to process the data you need to understand what kind of tools are available to you I am talking with respect to machine language. I'm not talking About writing a C++ code or something. Okay, so the machine understands bus just zeros and ones so the kind of Logics that are used to process zeros and ones they are called logic gates Okay, so they are very very simple. All right, so we will Directly get into the type of logic gate and then you'll immediately you'll be able to pick up. Okay, so the first gate Is the not gate? right down the first one is not gate and this is how it is Represented this is the not gate Okay, it has one input and one output Right, so let's say output is a and sorry input is a and output is y okay, so When input is zero, what should be the output? One it is not gate and when input is one the output should be zero Fine, so a table between input and output is called truth table so a truth table Is a table between input and output which lists down all possible inputs and outputs zero one one zero clear This is a truth table for not gate Not just reverses the input The second one is or gate or takes The maximum of the two As in it has two inputs and one output This is how it is represented It is why let's say input a and b Okay, so you'll have zero zero input zero and one input one and one input like that Okay, so can you quickly draw a truth table for this? So this is input output. This is a b and y Draw a truth table. Let me know once it is done Okay Brough faster everybody got it Yes, sir, okay one one will be what One one zero one one one one zero one zero zero So this is odd or gate all right Now we will uh see and gate and gate Is represented like this It is a flat back a b And this is why okay quickly draw a truth table a b and y In and gate it takes minimum of the two Oh, yeah Okay So when you have zero zero it'll be Zero zero one zero zero zero one zero And what else one one one one one one one one Okay All right, so these are the uh The most basic ones Then there will be a few combinations as in I can combine You know I can combine The and gate and not gate and I'll call it nand essentially What I'm doing here. I am putting And gate like this And then I am putting a not gate like that Okay, so it's a combination of two gates and uh It can be also represented Like this It just put a circle here It becomes nand you can see that Is a circle okay Quickly draw a truth table for this a b y Okay, so uh Nand will just give reverse of and isn't it? So zero zero should give you one One zero should give you one Zero one should give you one and one one should give you zero. Is it same as or The difference is one one zero and zero zero one Okay, so this is nand gate now. Let's talk about nor get Nor is as You have rightly guessed I hope Is a combination of nor yes nor get So it Get represented as this a very Samuel man I totally sir is not feeling well today, sir You know about everyone, huh? So no, sir No, he he did not come I think for last couple of classes anyways a b And this is why Have you drawn the truth table Yes, sir, it will be again reverse of or one one will be zero Zero one will be zero One zero will be Zero and zero zero will be one. Is it like and get oh one one zero and zero zero one that is a difference Okay So these are the uh few typical ones. Okay, let me quickly give you uh numerical and Then we can proceed further So why is nand called the universal gate? Why nand is called a universal gate? Probably I think it's because all the basic gates can be Generated from nand and nor yeah All right, so So what is the second one again the second gate? Tell me oh, it's oh, I didn't see I didn't see the spritter. I thought it was a square or something So So which gate it is closest to as in which gate it is I mean if you just have to Or is it like or So let me quickly do this a b and y Okay, so like kevin has message. Let's see what is zero zero Zero and zero if it goes from there. What will come out here One one will come out and then one one will go there. What will come out there? zero zero Zero zero will be zero Okay, then one one will be what one and one will go from a and b then here it will become Zero and then zero zero will go and it will become one Okay, similarly zero one will be one and uh One zero will be one. So it is the Or gate Okay, all of you understood those who are uh online Please type in any doubts You guys understood it's like uh an or gate There are two nor two nor gates are connected in series Okay, so let me repeat again see Zero and zero From a and b goes Then this nor gate will convert zero and zero into one and this one will be fed Both sides because it is split into two the same one one is fed One one is fed in a nor gate. So you get zero Okay, like that you can analyze fine. So Okay, let me Let me first finish this chapter and then I'll give you one numerical to close this off So towards the end there is a definition on integrated circuit. I see This is integrated circuits fine, so What happens is that when you make a circuit you have diodes transistor Resistance all that are connected. Okay, but then if you want to get the same effect and You have lesser space. You want to fabricate entire thing in just a chip Okay, I think you might have seen a chip. So the same effect can be you can get In a very very small chip And when you do that you call it as integrated circuits. Okay, these are electronics chips So what happens there is that you have a lot of logic gates connected In it fine and depending on how many logic gates are connected. They are different different names all right, so There Are let's say a small scale integration Which have logic gates less than 10. Okay, if logic gates number of logic gates In in that circuit is less than 10. It is called small scale integration ssi. Okay, and if logic gates More than 10 but less than 100 It is called medium scale integration fine if logic gates More than 100 but less than 1000 It's called large scale integration lsi and if logic gates Is more than 1000 It is called very large scale integration vlsi fine. So, uh This is just naming. Okay. They are not in our syllabus to study further Fun, but then some one or two mark questions can be asked on just the definition of it Okay, so let me uh give you a numerical and then we will Say goodbye to this chapter Okay, for this numerical also, I need to show you a figure Yes This one So example 14.13 you can see on your screen try to solve this The graph should look like this, you know, I'll show you say this is how the graph should be looking like and this this line sorry This line see this a is this horizontal line is zero It jumps up So when this goes up, it means one it remains one from t1 to t3 and then it drops to zero Then it becomes zero only and then it goes up it becomes one from t3 t5 to t6 It is one and then again it drops to zero Similarly for b from here to here it is zero and then it goes to one from t2 to t4 It was one so like this these are inputs and then when you draw the output You'll see that from zero to t1 time period a zero and b zero So likewise you can compare what should happen from t1 to t2 a is one but b was zero Okay, so like that you have to draw the graph And that's what you have to do for Steadland sir Those who are online are you guys done? Are they there is not there right? Yeah, I could not like not able to hear the train sound Why what happened to him? I don't even tell him So done what happened? Sir I don't know sir What? Okay, so this is how the plot should be is this what you have done Any doubt? That's us Yes, sir correct Those who are online Is this what you guys have done or you have any doubts? All right, so Chapter is over Okay, so this is it for semiconductors and You know treat as if This is an opportunity for you to score at least four four to eight marks in j names And it's very hard to find out good numericals on semiconductors Okay, so you have to literally search for it and look for numericals on Semiconductors, but you can start with Completing etzyverma Okay, and then look for previous year j question and let me tell you if you do that These four to eight marks are not going anywhere. They are in your pocket Easily All right