 So, you already identified your own set of updates, so you've got 100 mistakes in this field. So, you've got 100 mistakes in this field. So, you've got 100 mistakes in this field. So, you've got 100 mistakes in this field. Hello, hello, check one. Good evening friends, happy Republic Day. Hope there is not a confusion on which one it is, 66th or 67th, right? So again, moving toward the result diagnostic approach of understanding physics, we are today at the chapter Magnetic Effects of Electric Current as the title indicates. In the very one line, the stuff shows that in this chapter, we will study the effect of electric current, okay? So, what we are going to understand are the effects of electric current, right? Clear? So, fine. Now, these effects of electric current are actually on a wider note on heat, okay? We do understand the heating effects of electric current, okay? Heating is H, E, A, A is there and E is also there, okay? Heating effects, sure? Clear? Which we are not doing now. What we are doing is the magnetic effects of electric. Fine, so let's move on with that, clear? It will be an easy chapter because though the chapter is quite complex, there are many properties which are discussed in that chapter, okay? But here in 10th standard, as we are saying that this is a pretty result diagnostic approach, okay? We are not going to go into the deeper aspects of the chapter. We have already done that when we were in the classroom, right? In this approach towards the end of the year, towards the annual and the board exam approaching you, we are keeping it very to the point, okay? So that you can convert or you can translate many words received by you into schools, clear? So, so the whole chapter, okay, will be, we will try to conclude it by today, sure? As the chapter is having multiple topics as well as there are many variations also, different principles and fundamentals are discussed. It may take a time, clear? Sure, so getting into the chapter, the card one, the OSTED experiment. Yes, exactly. Mr. OSTED was the first person who actually identified or at least it is in the records that he identified that yes, there exists a magnetic effect associated with electric current. Sure. One day what happened by mistake is, he was having a current carrying wire. Actually, you might be, let's create a story. He was verifying Ohm's law, okay, for example. Sure. Now, there was a compass placed at a location near to that. Sure, clear? As he switches on, this compass was showing deflection. The magnetic needle was showing deflection. He recognized it and again tried it. First, so he thought here, this may be a just coincident, but then he repeated, right? How we confirmed the happening or something by repeating it, by again giving it a try. Right or not? Sure. Clear? No doubt. Cool. Cool. So, he repeated and he verified that yes, there exists a magnetic effect associated with electric current. Easy. The first name to remember from the chapter, Mr. OSTED. Okay. Easy. Sure. Now, as he defined that yes, there is a magnetic impact associated with every current, electric current. So, then came defining things like why if there is a magnetic effect, okay, what is magnetic field? So, see, very simple. Okay. For example, if I am speaking from there, there exists an area in which my voice can be heard and by coming into that area, that vicinity, someone can recognize, okay, this person exists. Right or not? In the very same way, clear, if we are talking about a current carrying conductor. Sure. So, this will surely produce a magnetic field. We denote the magnetic field by capital B or its intensity also by capital B. So, yeah, there surely exists a magnetic field. Right or not? Clear? But will you experience the impact of that magnetic field at a very far distance? No. Can be said theoretically yes, but that influence is negligible. Right or not? So, similarly, what is magnetic field? Though magnetic field tends to infinity, but what is it? It is the area around any current carrying wire or a magnetic material. It is the area around the current carrying wire or a magnetic material under which its influence can be felt by what? By what? By other material. Right or not? See, for listening me, for observing that I exist, someone who is coming here should have a capability to hear. Right or not? In the very same way, in order to detect that yes, there exists a magnetic field, the material should be magnetic in nature. Easy? Sure. The material should be capable of detecting the magnetic impact. A dust particle may not. Right or not? But yeah, an iron filling can. Got it or not? So, what is magnetic field? Magnetic field is the area around any magnetic material or a current carrying conductor under which its influence can be felt by another magnetic material. Easy? Sure. Clear? Now, what is a compass needle? You are very well aware about it. Okay, what are magnetic field line? Now, this is a very important part. And there is a very high probability that a question will fall from this. There is a less probability, you being in 10th standard, that someone will discuss to you about magnetic field. But surely they will have a discussion with you about a magnetic field line or magnetic field lines. Clear? Sure. So, let us understand magnetic field lines by the help of? By the help of? Yeah. Sure. A bar magnet. Clear? Suppose this is a bar magnet. Clear? North and south. Clear? Sure. Clear? By very concept, by experiment it is observed that if you throw iron fillings around it, they will arrange themselves in a systematic pattern. This pattern will look like this. Clear? So, see, by looking at the very nature, I myself draw it. Why? Because I wanted you to experience that. Okay? I could have used a picture, pasted here, but I did not wanted that because if an exam it comes, you got to draw it by yourself. Right? So, simple thing, note down the things that the field lines move from north, okay, to south. Outside the magnet. Clear? Sure. And within the magnet, they go from south to north. Easy point. If you see here, no two magnetic field lines are intersecting. No two magnetic field lines are intersecting. Clear or not? Sure? Easy? Paka? Cool. Why they are not intersecting? We will talk about them. Okay? Sure. You will see that the magnetic field lines are denser, nearer to the poles. North and south are what? Poles, right or not? Clear? And they get rarer as we move away from the field. Sure. These are fundamental or basic natures. Okay? Of, easy? Clear? No. Understand that this is the property or the magnetic field lines associated with bark. Let us now see the magnetic field lines associated with the current carrying conductor. Because what Orsted did is, he recognized the field around the current carrying, sorry, sorry, conductor. Okay? So for example, current is going in this way. Then the magnetic field lines will be like this. Circular. Okay? They will kind of make concentric circles. Okay? Sure. Clear? So you can easily do that. Like if you will put a card here and there is a hole, the wire can pass and if you will put sand over there, not sand, iron fillings over here, the iron fillings can arrange them in this way. Why sand? Because recently we did this kind of thing, not with the current carrying conductor, but with the plate for sound waves. Clear? Sure. Sure. Now, when we talk about these, there comes a very important rule which is known as right and thumb rule. Easy. Now what does that indicate? It states that if there is a thumb held in the direction of current, then the willed fingers will tell us the direction of, I am quite bad at drawing, but the willed fingers will tell us the direction of magnetic field. Clear? Sure. Easy. You know right hand thumb rule. This is the right hand. Okay? Sure. Why? Cool. Similar to right hand thumb rule, there are rules like screw rules. Okay? What does a screw rule indicate? It states that if there is a thread and yes, the screw is given like this, then if you turn the screw you will apparently see the threads going up. Right? Sure. So the direction in which screw is rotating is the direction of magnetic field and the direction in which screws are apparently moving is the direction of current. That's screw. Simple. Sure. So these are the fundamental rules. Okay? Discussed. Post understanding that yes, there exists magnetic field associated with current. Okay? Sure. So this is what we have discussed about the field lines associated with the bar magnet. Okay? Now characteristics of magnetic field lines. So I discussed four primary characteristics that they are denser nearer to the pole. They are rarer as we go away from the pole. They move from north to south. Outside the magnet, they move from south to north inside the magnet. Clear? Simple. No doubt. Now simple question that why two magnetic field lines don't. Interesting. Okay? Sure. So now see north to south these fields are being drawn at any point when we place the magnetic compass, the tangent directs towards the direction. Now for example, for example, two field lines are intersecting. That means that at this point, there are two different directions. For example, it's showing north here. And then at this point, there is two norths. This is really not possible. Right? For that sake, two magnetic field lines can never intersect. Clear? Easy. This is the only conceptual question which can be drafted from this topic. That is the properties of magnetic field lines as you are in 10th standard. Okay? Sure. Clear? You can read it out. The compass will show two directions of the magnetic field line which is not possible. Exactly explained in the same way. Sure. Clear? We have understood how the magnetic field is experienced around the current conductor and the thumb rule also. Clear? Sure. No doubt. Now, the primary thing is the magnetic field due to a current carrying loop. Circular loop. Understand that this is very interesting. Okay? If you have understood this, you can see the more part of the 15th question for the game. See. Suppose there is a current carrying loop. Just watch. Okay? Clear? Now, this is the left-hand side. This is the right-hand side. What have I done is I have kind of tilted it. So what you see is something like this. Okay? So the left hand more toward you. Okay? I have tilted it this way. Left hand more toward you and right hand quite away from you. Writing it short because it is away and this will be clear. Sure? No doubt? Sure. Easy? No. For example, just simple understanding, have this understanding very clear, very clear that suppose this is the direction of current flowing, which is clockwise. Okay? So even the current will go kind of up from here and will go down from here. Right or not? If you will apply right-hand thumb roll, this is the direction of the current. Clear? Sure. Okay? The magnetic field will go like this. Inside, outside. I don't know. Similarly, if you look here, this is the direction of current. So the magnetic field, so here will go this way. But again eventually will fall inside the circular loop. Right? Sure. Clear? If I just put this circular loop in such a way that you see nothing but this. Clear? Then what will you see? What will you see is like many lines are going in and coming out even from up and down. Someone's thumb is on. Okay? Go down. So what will you observe eventually is that many lines are going inside the loop and coming out. Okay? Similarly, going inside the loop and coming out. Right or not? Sure. If I draw this in this, then you will see this. Going away from you like going inside the loop. Clear? Sure. And coming out. Easy? Clear? Now, if I ask you what is the difference in the magnetic field lines, then there is no difference. Right? Is there a difference in magnetic density? Yes, surely. The magnetic density inside is very high as compared to that. I don't know. Sure. Easy? Clear? Clear? So, now just try to understand this. There exists, suppose, there exists two such holes here. Okay? One. Two. Okay? Okay. Multiple. Three. Just to make you recognize it well, I am just trying. Okay? You can understand it from one way. What you are seeing is that the magnetic field lines are going this way inside and going this way outside. By the very property of the magnetic field lines, by the very property of the magnetic field lines, inside a magnet, they go from south to north and outside the magnet, they go from south. Not to south. That mean what? That mean what? It's quite a simple thing. Simple thing. For the same single current carrying loop, if you look at the, if you look from here, what is the direction of the current flow? Clockwise. Right? So, for the very same loop, if you look from the direction where the current appears to be clockwise, surely appearing. Why? Because if I go to the other side of the loop, it will appear anti-clockwise. You can imagine it very well. Right? Yes. Hello. Hello. Hello. Check. Yes, sir. Ok. Ok. Ok. Ok. Going back to the agenda. So, all this while, was I not audible or for a good duration? Not for like one minute or so. Repeat? So, for one minute or so. Ok. Just like that, right? Yes, sir. The whole while I was audible, right? Yes, sir. Cool. Thank you very much. So, we were discussing, should I repeat from where should I repeat? So, the S and N after you do that. Oh, fine. Thank you. Thank you very much. Thank you very much. So, simple. Very good. Sorry for the inconvenience. I saw that the mute button got to you, but I don't know from where, because I was on the screen. Ok. But let it be. Now it is ok. What I have explained here, I will repeat it. Ok. If you will take this loop in consideration, I have drawn it here. So, if you can see the clockwise direction. Ok. And then tilt it this way, that it looks like this, or making it more tilted like this. Then you will see that, toward the south or toward the clockwise, is the south pole, and toward the anti-clockwise will be the north pole. This image explains this well. As the current is going clockwise here. Ok. What you are observing is that, so no. So, that the magnetic field lines are going this way, and then coming out. And by very nature, which we understood by the north and south pole, that this is the nature. Right? Clear? So, using the same application, we can conclude that toward the clockwise end, it will be a south pole, and toward the anti-clockwise end, it will be a north pole. Easy. Ok. Very good. Next one. Now this is very important, the solenoid. As I tried to explain you, with multiple terms, this is what exactly is solenoid. Ok. But it is a, I have drawn multiple loops. It is a collection of loops drawn by the same wire. All of them are connected. Ok. I will just, there is a easy way to draw very beautiful and comfortably understandable solenoid. Tempting between the lecture. Simple. Draw a ball. A ball. Ok. So, don't take any shape now. What I am doing is by just, by the help of this. See, easy. We have to mark the most exhaustive option. Sure. Clear? This is a solenoid. Any conducting wire, bound over any core. See, the core need not to be a hard one, as I have taken it. It can be air also. So, any wire, any conducting wire, bound over, bound over, a core. Ok. So, it makes a solenoid. So, what happens in a solenoid is, as the current goes in. Clear? So, if you look from this side, it is very easy, watchable that this is the way it is going. It is the clockwise way. Right or wrong? Clear? Clear. So, what you should see is the south pole here, and then the north pole here. So, if someone... If it be a... Isn't it anti-clockwise? No. See, if I... Got it or not? Right? Yes. I'm sure. It's coming from back, going like this, right or not? So, it is a clockwise way. Clear? So, if somebody will ask you to draw the lines, you can. Why? Because you know the very nature of the magnetic field lines. Simple? No. As I have kept a hard core here, clear or not? Sure. Now, if this core is a material which can receive magnetism. Magnet... Sorry. Magnetizable. Which one? This core. If the core is magnetizable, the solenoid can act as a very good magnetizer. If you put a magnetic sensitive material inside the core, inside the solenoid, this magnetic material will become or will act as a magnet depending upon its very nature. Based on the nature of magnetic materials, we have diamagnetic. As the flow... Ask it. I'm just explaining it here. Paramagnetic and ferromagnetic substances. Diamagnetic substances are those which oppose magnetism. They don't get magnetized. They oppose magnetism. Paramagnetic materials are those materials which get magnetized. Which get magnetized for a temporary, for a small time. Temporary magnetized. Clear? And ferromagnets are those material which once magnetized retain their magnetic strength for a good duration of time. Easy? Sure. So whatever material you put in a solenoid, the similar kind of response you get. Clear? Not a problem? Easy? Now, there's a good probability that the line can come. What is solenoid? And draw a schematic representation of magnetic field around solenoid. There's a good probability of this question being asked. So mostly, I hope most understanding the circular loop, you don't need a different understanding for solenoid. It's pretty same. Rather, there are multiple loops here. Okay? In solenoid. Clear? Which actually makes it simpler. My personal understanding. Clear? Now, that's what I was explaining. The permanent magnets, temporary magnets. Those magnets which are temporary, we call them electromagnet. Why? Because they will show magnetization or they will show magnetic properties. Only till the time they are being magnetized. Like the electric bell. Right or not? As you switch on the bell. Clear? Sure. The solenoid makes the core magnetic. Sure. And hence, there is a steel big part and there is a clicker. This clicker becomes magnetic. It hits it. Clear? It creates a sound. Easy. Sure. Electromagnetic. Got it? Even in cranes, we use electromagnets. Even in my MacBook charger, is there electromagnet? Clear? Easy. Sure. So what are electromagnets? Electromagnets are the magnets which show magnetic behavior, magnetic attraction, representation. Only till the time the magnetizing force is switched on. Easy. Sure. As you close the magnetizing force, they will act as a normal magnet. Normal material, not a magnet. Clear? Easy. Sure. Now understanding this very important topic. Force on a current carrying wire. There is a shift to a chip. It has to be card 15 first in this. But not a bomb. So force on a current carrying wire. When this wire, which is having current, we by very nature know that the wire will produce its own magnetic field. I don't know. I have two spaces. Okay. Sure. If this wire is there, current is there, then it will have its own magnetic field. I will add a magnetic field of wire. Okay. Sure. Now see, not this magnetic field, but if this wire is placed in an external magnetic field. Clear? Sure. Then this wire will experience a force. Now this force will be equal to current, length and magnetic field. I, L, B. Okay. Sure. What is that? I am a fool, I think. Gladly. Now, what is this I, L, B? See, I is the current of the wire. L is the length of the wire. But this capital B is not of the wire, it is external. This is the force experienced by the wire. Clear? Now, actually this force comes from Lawrence, okay? Lawrence explained that the force experienced by a charge will be Q, V, cross B. I am not stating it here, but it is Q, V. Okay. Now what we have made, this will never be as in your exam, I am just explaining you. So as there are multiple charges moving with current. Clear? And it is having, when charges charge can I write the velocity as distance covered upon time? By the way, on the figure it seems to be 1. Q by T is nothing but the correct. So this is how this expression was observed. The one who is applying the force is not the magnetic field generated. By the way, I am scanning current. No, it is an externally applied magnetic field. Even within this figure if you look carefully, you will see that this magnet is the externally application of the magnetic field. This is the wire which is having its own current. So because of its current, this wire is experiencing a force which is generated by this magnetic field, the externally applied magnetic field. Okay? Easy. Quite a very important topic, even you can see there is explanation as of now we have not seen the formula. Clear? Easy. Sure. Clear? No. What is the direction of this force on it? It is explained by Fleming's left hand rule. Okay? Left hand rule given by Fleming. It is Chotu F. It is a person. Capitalism. Very simple. Hold your hand. The left hand. Clear? In such a way that the thumb Okay? Sure. The middle finger and the index finger. So are mutually perpendicular to each other. Now it is nothing but the direction of F. From diagram it seems to be one part to be If the magnetic field and current are mutually perpendicular to each other this will be the direction of the force. Clear? Easy? Sure? Sure. Hmm? No doubt. Great. This is Fleming's left hand rule. There is a right hand rule also which is used under magnetic induction. Okay? Whenever there will be electromagnetic induction Fleming's right hand rule comes into action not the left hand. Okay? What is the way to simply remember it is? F B I. Clear? Sure. Now the functioning of electric motor. Very important. And I would love to appreciate the person who created these cards there is a mistake no problem but surely and properly put at the right place. See generally guys what happen is you make a confusion within yourself that both the electric motor and the electric generator works on the principle of electromagnetic induction because both are rotating now actually. The principle behind functioning of electric motor okay? The principle behind functioning of electric motor is based on the fact that any conductor which is placed in a magnetic field and it carrying current will experience a force on sure? Clear? Hmm. Sorry. Sorry. So I will just draw a schematic representation here schematic representation okay? Simple. Suppose this is a coin. This is the armature connector. Now if you supply current to this current will go this way this way this way also okay? Sure. Sure. If there is an externally applied magnetic field north to south then the field is acting this way clear? Clear? And for these two arms okay? Apparently this is also an arm. For these two arms the direction of magnetic field and the current is same they are parallel. So there won't be any force active. Clear? Sure. Now if you try to adjust your left hand rule in this line then you will find that the force is acting downward. Check it. The force is acting downward here for this line. Okay? You can tell me if once done is the force acting downward? Down right? Similarly if you apply that for this line then you will find that this is acting upward right or not? I am not focusing on actually now this coin as it is completely connecting kind of having a feeling to turn this way right? And that is how motor works. You supply electricity and it turns. Simple? Clear? Clear? This is a fundamental understanding of how a motor works. Clear? Clear? Now there are shortly certain auxiliary parts which do play role in the performance of a motor. Like there is this shaft which actually rotates. Clear? There are brushes. Clear? There are splittering and all about them you can easily understand read but do remember them because this is one of the highest probable question which can be asked. Explain the working of the motor. Clear? Clear? Cool. Now come Sir Faradi and he explains an excellent concept of electromagnetic induction but before going into it I would just want to add on because in 2009 one time this was okay and actually in 2012 the pattern was changed C came so things got changed and again they have introduced the same board pattern again so there is a probability that things which used to happen before 2012 may be repeated. So in 2009 mostly in 2009 there was a question asked for a mark but good one. There are two current carrying wires. I and I so they are at some distance both are having different or same currents okay immaterial. So the question was what will be the force acting on wire 2 force on 2 due to one attractive repulsive coming out of the paper going into the paper. What is the direction? Sir it will go up it will go up in the same way this way yeah think again So then they will go closer I see suppose for example we are checking the force on this wire right? yes sir simple by this wire a magnetic field will be generated yes or no? yes. By very right and thumb rule this magnetic field will be downward yes or no? yes any doubt in this? yes so as electromagnetic induction is not happening we will apply left hand rule sure finger B index finger is inside right or not clear if you will see then the I is upward please tell me that the force is either this way or this way please A or B sir B left hand left hand rule B the capital B the index finger is pointing inside the screen right or not? yes sir the current going up so yes sir so the force will be toward A am I right? sir how do we get the magnetic field sir? repeat which magnetic field will apply a force on to the magnetic field by one right or not? we had in discussion the external magnetic field will apply the force right? yes so who is the external magnetic field source the I1 right? yes so the magnetic field due to I1 will be by right hand thumb rule right or not? will be going in plane of paper oh yes sir easy yes sir this was a question asked mostly in 2009 but I I witnessed this question I encountered it sure going in opposite directions repeat if the current is in opposite directions then so you can easily remember I did not wanted to dump in one more line to remember in your brain but simple in the case of two current carrying wires place parallel sure same direction current attract opposite direction current simple okay? easy but you want to remember it so that's why I did not wanted it to happen it's okay without any effort can remember it right or not it's just the opposite case of charges okay? yes sure so now getting into the Faraday's law of electro magnetic induction okay? clear? so what happened with Oster sir right? was an accident he accidentally kept his compass or magnetic middle near an electric circle sure and he got a result that no electric circuit is not just electric it is having its own magnetic impact right? in the very same course in the very same way Sir Faraday made a mistake okay? sure what he did is like he was having a solenoid and there was some experiment going on sure? by some way it may be a story but yeah it's okay to develop a concept around that story by some way he apparently created or generated a relative motion between the magnet and the solenoid and he observed that the gildano connected with the circuit is also showing the reflection okay? which gave an idea that no when there is an interaction between electricity and magnetism then there is again something extra okay? sure? and then he proposed and he experimented further and researched out that yes there exists something beyond electrical conduction which is induction and as induction was an outcome of electricity and magnetism it was named as magnetic induction easy? yeah now see what is electromagnetic induction so whenever there is a relative motion between electricity and magnetism sure? clear? sure? and impact is generated now where is the impact generated? and impact in air? do you feel electricity in air? no right? where is the impact generated? so see understand this as we have defined there exists something called as magnetic field lines right? we have also defined the line densities right or not? the density of magnetic field by definition there exists a term flux magnetic flux which is the product of number of magnetic field lines given here when you go to 12th standard you will see this as vector B dot vector I clear? now it is as of now magnetic field multiplied by area clear or not? sure? not a problem? clear? so when there is a relative motion electricity and magnetic field there comes a change into this way change in flux leads to electromagnetic induction ok? sure? what is flux B into A? so by any means you change B or A or both flux will change and change in flux will be electromagnetic induction for example what is Farada's experiment? I am just explaining you with the help of a Gilvanometer ok? for example where is the bar? ok? around the bar there is a clear? again looking from this side it is a clockwise kind sure? so for sure there will be a south pole here and there will be a north pole here no doubt what is happening here? understand this if I take a magnet for example with the north pole this way the net magnetic impact here is increasing or decreasing? fast decreasing why? because north is cancelling south as more north will go towards south it will become more of a neutral point ok? so as you see this the B is decreasing A is constant right or not? but B is decreasing clear? the combination of that flux is also decreasing flux is decreasing at least denotes that it is changing and by Farada's law ok? change in flux with respect to change in line time induces an EMF clear? sure now for example there are more number of turns then it will be N also adding the lens statement to it that every effect opposes its own very cause then as this north is going away the change want to cancel this north going right? so it want to generate clear? something which can go right or not send the north away that means north again clear? so it will induce an EMF such that the current generated will have such an impact that a north will be produced here that is immaterial for you what you can understand is by Farada's law E is equals to minus N instead minus N d phi by dt change in flux with respect to change in time so what is galvanometer? galvanometer is the device it is not a measuring device it is just a detecting instrument galvanometer is a detecting instrument which just detects or checks the variation of just detects or checks the existence of current so all the variation of current is also clear? beyond this Farada also experienced that as I said opposite and all that north creation of north and south Farada also experienced that when you take bar magnet towards the coil for example in that case if it is showing left hand side deflection then when you bring back the bar magnet then when you bring the bar magnet then it will show opposite side deflection so even the relative motion and its direction also varies clear? now why this current is being generated or induced it is because of electromagnetic induction creating an electromotive force which is eventually breaking the current as the current comes there is a resistance in the wire so you will eventually get this expression also so slowly from this line we move toward alternating nature Farada's experiment was an excellent one there that actually changed the whole virtue or the whole trajectory of world's faith when Farada did this experiment generator was able to be created we were able to create the generator and then electricity came and everything took a different course everything took up may not be a different course but a different rate of expanding and the different speed was inflow for the world to grow all this industrialization and all that we can see electricity which is coming from a generator really from a generator either you use a nuclear power station or you use a thermal power station that is from the very basic to the very advanced all this is leading to a generator being rotated by the help of a turbine so generator is what giving you and me and all of us the electricity which we are we take to leaving this social lecture apart can we proceed I just got flown into a different mode kind of drowsy today ok so now understanding how the electric generator works the construction of the electric generator schematically is kind of same schematically I said kind of same as of electric motor only when you look at the electric motor you give electricity and take a mechanical work in a generator you give a mechanical work and take electricity one second so generator simple line as there were in motor coil as there was in motor see here we add a gear this gear is help to rotate it I remember my childhood days we have seen the generator getting started so at times there were I have seen two types of generator one with a handle supported by it with which there were one or two quick rotations not just small like not like a child rotating it very quick and forceful rotations required ok to turn this quite ok as I grew up I saw I witnessed a honda generator I will state that name also it was having just a holder here you got to pull it easy to start really you did not needed a force right just a kid can also start by saying a kid I mean of your age ok sure not a kid of who is in fifth or sixth and all but a bit grown 8th 9th 8th 9th and all that ok you can relate a kid of your strength ok it's quite a relative thing so when you pull this what happens is the squire comes into rotation as the squire understand this is this is this is a bit different ok clear squire rotates now as you say by a rotation there is there doesn't appear a relative motion like I said in order to generate electromagnetic induction in order to see electromagnetic there has to be a relative motion between B and A now there is no motion happening only circular thing happening going up so how the flux is cutting how is the flux changing because without changing the flux whatever be the number of turns you can't bring E and F right see very simple line very simple understanding keep your hand ok in front of your eyes so like the way we salute if you are aware about that the way we salute we keep the hand like that right so bring it in front of your eyes now try to rotate it rotate it it is very clear to see that the area which is coming in front of your eyes is different right easy and this is the way the flux the B dot A got changed in generator easy because see every time you can't generate you cannot whether these guys have earlier tried to create a generator which is was moving relatively having a solenoid and a bar magnet and like a drill going in and out and all ok I don't know about it but even if they might have tried it would have been really difficult for them to continue it why sure because in order to achieve that kind of movement quite difficult so whoever has thought it that utilizing of rotation and cutting magnetic field lines excellent ok if it is serfarade then he deserve to be called as ser right so the rotation actually cuts the flux we use this term cutting of magnetic flux so the rotation cuts the flux and eventually change in magnetic flux is observed I don't know clear so we see this d5 by dt and whatever be the number of turns and whatever be the number of turns equivalent variation in emf will be seen sure easy this is how the generator works clear again stating here there will be auxiliary passing generators ok you can go through them understand their functioning it's quite an easy thing sure ok for the basic structure and working is same ok sure clear in generator you give mechanical force and take electricity out in a motor you give electricity and take mechanical output simple this is the fundamental understanding ok and the difference also there is a difference in motor regulator beyond in the vertical of the basic principle they work right sure generator works on generator works on electromagnetic induction not the motor motor works on the principle that a current placed in a magnetic field and external magnetic field will experience well experience oh beautiful figurative representation right sure beautiful if you can draw like this nothing like beautiful I love it sure clear so the motor functions on the line that whenever a current carrying conductor is placed in a magnetic field the experience it will experience force ok sure the topic which is in front of you now self induction ok is actually now being used in generator in transformer sorry ok sure they are single coil we are we call them auto transformers generally transformers I am an electrical engineer also so in transformers we use two coils ok there is a primary we will read about it we have already read about it we have discussed about it so there are primary and secondary coils but there comes a transformer which is having a single coil or a single cylinder which may have two coils which is known as auto transformers ok in that we use self induction and mutual induction I will answer ok let it be of the shore ok we will continue our own course and like by saying the course over here I also mean the course the flow if you guys are aware of the navy terms so let it be so let it be what is self induction so as of now what I am saying is T if this is a coil there is another coil if you change the flux associated with this there will be changes observed in this so this is mutual induction this is mutual induction self induction means within itself clear easy so going coming so within itself the changes will happen clear ok easy clear self induction capability is measured at self inductance ok inductance of a coil when you move to senior classes you will read a word see this is mutual inductance primary one coil and second coil if you will change the flux of one mutually another will be changed if they are mutually linked primary point see if one is in Bangalore another is in Mysore they won't work clear they got off the place in a magnetic linking within a transformer like that so they will see mutual inductance easy so when we use induction PMI we apply Flemix right hand rule ok clear same I don't want to introduce another term air motion not required motion is nothing but force field is magnetic field and current is current so as B and I the later two are same let keep the first one as same motion and force the direction the force will act the motion will come in the same direction so though it is stated in different pictures that consider the left hand rule as FBI it's an easier word for your generation to remember ok clear FBI so ours was 100 and US generation is 9-1-1 don't dial 9-1-1 in India it doesn't work so simple for left hand rule we discussed about FBI keep it very simple for right hand rule also FBI just understand that this force application will bring change in motion the direction the force is acting the direction is the movement who is moving the conductor easy no doubt very good ok the chapter is edging toward the end ok clear now as you are aware about the generator ok you can also identify that as it is rotating two types of waves will be generated one wave will be having a positive nature another apparently and in comparison right or not you can't define being positive and negative unless you have a ground reference right so one is a positive another is just opposite to it that's why it is also known as negative so positive and negative and as nature of flow is alternating as the very word says so we call it as alternative current clear the one that you get from battery cells it is direct current it's a similar line which comes to you clear so there is a very simple difference but they do the two currents alternative current and direct current their performance their action is very different like literally they act in very different manner in different like even when we are transmitting sure like you may you guys are quite curious I expect that you might have been through a google search at least that why don't we use DC in India why we use AC right the primary reason behind that is not DC being less adaptive or DC being less efficient surely DC is way more efficient the problem will be there will be a whole new transmission system which will be required we need a whole completely new transmission lines if you know like giant towers right when you go on roadside even in HSA there are few we have in HSA where there is a small substation right you can see giant towers all that won't work when we will jump into DC ok so DC will be more efficient but it will surely take a very high bandwidth of capital investment and that is the primary reason we are not adapting the DC even not we the growing countries even the developed countries are even giving it a thought just giving it a thought even on paper ok so that ok let's plan to adapt DC but it is really hard to adapt DC DC at domestic level very good so because see when we adapt DC we can easily move toward non-conventional sources of energy right all these very modern sources of energy can easily adapt DC especially the solar it is DC it is charging battery and using it for later purposes ok so I will not deviate much ok pull me back to the lecture talking about what is there in 10 standard as we are in a result agrostic approach clear sure easy sure there are few points of comparison between AC and DC I was giving a lecture over it ok so we can talk about positive nodes also we can talk about negative nodes also positive on action when we talk that how AC is helpful or how AC is ok better than DC the primary thing is the power losses the heat I2R will be less in AC ok sure clear also the instruments which work on frequency like the transformer the transducers ok they do they can only perform on AC transformer is an electromagnetic inducting device electromagnetic induction will not act in DC this is a problem big problem we will have to change the transformers right simple these are the primary advantages of DC oh sorry AC over DC now I would hear just officially state here these are not the problems with AC or DC these are the problems with us Ankit these are the problems with us as we have not developed a device which can receive it already so easy sure so as I discussed with you in the last lecture that there is a word named as domestic electric circuit I have a question yeah please since we get AC light and there is one live wire and one neutral wire ok dear AC shouldn't the live and neutral keep switching aha no dear neutral means no charge whereas positive and negative is something right or not ok so like when it's positive then it's coming from the line to our house and when it's negative it's from the house to the line no no no not like that there comes a positive cycle and a negative cycle what does it mean it actually doesn't mean that something coming and going it's not a oscillating thing you are getting my point oscillation is one time coming toward you one time going away from you right or not yes sir it's not that what it is I will explain you simple so clear understand this very clear really very clear these are the north and south pole of the generator clear this is the coil clear so as you are turning see at your reception and you are not changing the terminal are you no right or not your reception terminals are static clear as your coil is rotating one time this one is touching one time this one is touching right or not so one time you are experiencing this kind flow of current another time you are receiving this side flow of current but both flows are being received at single terminal am I clear yes sir as I said it's a relative right or not nothing is positive okay and nothing negative until and unless you have the ground reference right so as we call the first one as positive this is negative for a part of utility yes machi you said that neutral wire doesn't have any current right but short circuiting happens only when live when neutral needs so how does that work exactly see what happens is see simple huh this is the supply and right or not this is the phase and the neutral end clear as you said okay that if this wire and this wire will come into connection clear a short circuit will happen right why the reason is the same thing that this wire doesn't have any supply as of now right or not clear okay this wire is having as they come into connection the resistance between them which is making the circuit work okay sure will disappear and hence there will not be any getting my point there will not be any square by R the power utility okay whatever goes is square by R the heat and as more of heat that's what you see in the form of fire easy yes sir thank you okay param am I clear for you as well yes sir so like even so like how does alternating current manifest itself like in direct it just remains constant like when we are actually something which is to be used right now in alternating current this is the case right yes sir this is also a utility for us and this is also not a utility for us why the reason is like our device is there okay our devices our appliances are designed to convert this into productive cycle got it okay so when the negative like when the negative part is coming is it possible to detect the oscillation between positive and negative yes we can we use a term named as a device named as rectifier okay so when you go into 12 standard okay so you have the same chapter EMI and AC again okay you will have this word rectifier this rectifier can easily convert also normally direction it can easily convert the complete wave of positive and negative into only positive or only negative aspirates program okay this rectifier is made of electronic devices okay so but if it like changes it from positive to negative then it's only positive so how's that alternating no but then this happens this one rectification happens okay we use it as a DC we further convert it to a uniform supply okay so okay and then we use it as a DC it is generally done in your electronic devices we these days don't use much of electrical devices we are rather sure electronic devices right or not if you remember your grandparents home you might have observed the fan regulator right or not which was having a channel yes or no yes sir yeah yeah yeah kitch kitch kitch like that right or not and now at our home okay so the fan regulator is very smooth very small also right it doesn't clicks like kutch kutch kutch right it just goes round yes or no so this white one which we use now fancy thing small thing is electronic whereas that older one was electrical and why this kutch kutch was happening if I have taken your class then I might have explained you that it just changes the value of the resistance putting the click putting the needle okay at the proper resistance place yeah so as the resistance will vary the absorption of current will vary and so do the rotating force right or not yes sir how does how do the current regulators work then like the ones which you use now okay the fan regulator yes sir is it like got to do something with the speed of the motor yes exactly absolutely correct you know that the motor works on IELB right or not force is equal to IELB right or not yes sir so by changing R you control I because force the designing is done right you can't change L neither be you can't change the size of the regulator or the wire neither you can just magnetic which is inside that regulator right yes sir so what you can eventually change is only I so that that is what you use so okay similarly there will be a question when we go through transformer there will be a question in what way can you increase the efficiency of a transfer okay suppose the designing is done we really can't change anything it's a closed box right yeah so for changing the efficiency we will have to look for options which are viable okay so easy so but like in a transformer the more tightly packed the coils are the more efficient it will be oil is nothing in EMI oil is just a coolant as you know that as electromagnetic induction will happen current will come I square I will be there no no no sir in the like in transformers when you have the like when you have the coil the one in which electricity is going through like if you put more turns inside the coil turns not oil but yeah yeah by definition there is a technical term turns per unit length if turns per unit length will be more okay so more EMI electromagnetic induction will be observed if turns per unit will be this what is the name of that definition which definition Bite the turns per the turns per unit length okay it's not the definition it's the principle of working of a transformer okay what is the transformer by definition as the very word indicate transforms okay transformer is a device it's a static device see if you look into other electrical devices there is one or another part moving right like in a fan a motor is moving right or not yeah sir but transformer is such a device in which there is no movement it's a static device okay so this is something which makes transformer is one of the most efficient device in any vertical okay transformers are having an efficiency of 96% there is no electrical appliance which works on that great efficiency why the reason is there is no movement so no mechanical because of that it will stay for a longer time and stuff yeah this is the way because there will not be any wear and tear there will not be any yeah there will not be any mechanical losses right that because it is being used it is getting friction and all right easy also these days you get like really advanced technologies to cool down if you know there is a masters vertical when you after pursuing your bachelor degrees in technical whatever it may be it may be an arts degree and all that so when you pursue into technical bachelor degree you go for a masters bachelor technical degree right in masters there in an engine ring which is like very famous these days pooling engine so a person who pursue pooling engineering pooling that vertical I am not aware about the absolute term of it but yeah it is working on coolings something which can cool something down so all the devices which work they get heated up you know it very well at whatever even Antarctica is some machine is working it is getting heated up right or not so these engineers who pursue the masters there is no bachelor vertical as of now I am not aware about it but surely there is masters vertical MS or M tech through which this technology is in high boom ok so people read about how can I decrease the heating influences how can we cool down something so these days transformers are coming not with oil not oil cool transformers ok the transformers are coming with silica gel how does that help ask what oil do hmm tell me what oil do in a transformer what will the oil do oil helps in cooling right sir yeah exactly right the heat which is produced oil absorbs it ok sure see whichever engine you see it may be a transformer it may be engine of a motorbike sure it is having oil in it right or not so the primary function of oil is to reduce friction if there are any movements luckily in transformer there are no movements so the only function of oil is to cool down cool ok so silica gel is more efficient in cooling it is more thick right sure and it has got a high heat reception capability in comparison with oil ok sure there is a term fire point and flash point what is the fire point and flash point see if you have seen at at home mama gives a tadka to the dal right yeah yes what she do she takes oil in in a spoon sure in a spatula which is quite big in size ok so in labs we see a spatula which is very small at home we have a spatula we use to serve ok which is a bit big in size so she takes oil and ghee into it right and then heats it right and eventually it catches fire you know it right or not a small fire a small spark yeah so beyond a certain temperature limit every oil ok so catches fire so silica gel is better on that ground because the fire point of silica gel is way higher than oil so you can heat up silica gel to a higher extent that means eventually what the silica gel has got a higher heat reception capability than oil easy kind of deviated from the actual lecture course ok easy hope it is answering your queries right yes sir sure so looking at what we actually started with is the domestic electrification right so general question that why we use parallel copies electrification at home instead of series param answer so I couldn't hear that what did you say I asked that why we use or why we opt for parallel electrification at domestic at home instead of series sir because in series the voltage gets split so each one will not get 220 volts and in parallel you get 220 volts for each one and further more if one breaks down then the rest the other will function still and it's like independent because voltage is the one which is priority point ok yes sir in board what is required is not just we know thing it is what is required is what you have written right or not someone doing less than you but representing it fairly good will get more scores right yes sir so the second point which you said is the priority point ok ok in series there is a problem if one part stops working if one part of the circuit get damaged the whole circuit will not function whereas in parallel the other can continue working primary thing second thing is what you said at the first ok so yes sir very good what is the function of fuse safety devices which which safety devices fuse fuse oh fuse it has a low melting point so it melts and breaks the circuit if there is extra current if there is a current flow i square r impact breaks the current right so that is why it is better to state the formula the fuse wire is made of such a material which has got a low melting point ok sure on that round here I would state that in 2011 I think a question had came what is the modern replacement for fuse mcb's miniature miniature circuit breaker very good ok and on what principle does they work I forgot what happened in a mcb if the current goes above a certain like limit then it just switches off actually the word is strips but how you hear a sound cut right there is some kind of spring there right after a certain current it activates the spring then this lecture will be uploaded on youtube right you got to answer this in the comment I will check the assignment ok ok ok we are moving right ok sure so what is short circuiting we just now kind of had a discussion I see there is a very good difference very nice point stated there is a very good difference in short circuit and overloading right or not and overloading may not cause a short circuit ok sure it can be a case that the circuit is overloaded but it is working but in short circuit the circuit won't work ok short what is short circuiting when the resistance of a working electric circuit by any mean by some moisture some water into it moisture into it or by an external conducting material or just by connection of phase and neutral wire goes down the current raises to a very high extent which by joules law creates a heating effect and this heat we see in the form of fire right or not this not only this not only damages a circuit but also damages the device ok sure what is overloading when the appliances are supplied with an energy beyond their power ratings every appliance will have a power rating right or not a bulb 100 volt bulb will work on 220 volts right or not here so it clearly states that baba don't give me energy beyond this else I will burst out ok so basically more power that's given than it like the appliance can handle not even more power even in case of less power ok it is accessible why because it's like a thread ok look at it from both ends at the supply end and at the reception end clear yes sir so I found out how the MCB works I said great have you googled it out or just thought about it so like I thought that there has to be some mechanism with which it closes in the circuit very good I don't know exactly what it would be right but I knew that since that small that it can't be something electronic like mechanical exactly so I will prove that generally we won't have found in electrical things you have some ok yes sir so please proceed so it uses a like it uses a solenoid as an electromagnet once the current passes the safety amount then the coil gets activated and like the switch which is keeping it open the switch will close yeah I was thinking it has something to do with electromagnet but I wasn't really sure so another question on that ground para ok this is the case in education you do a work you will get another ok so the course we have electronic iron boxes at home for which we can set the temperature are we ironing a silk cloth or are we ironing a denim cloth so we can set the temperature and automatically it trips after a certain heating limit how that works does that um you want us to find out what how that works I just want you to guess so when it reaches a certain like temperature that cuts off the circuit so how that cutting is happening I think some element will maybe get heated heated up and that will like transform very good both of you very good we use a conductor made of two metals we call it bi-metallic strip ok you might have been through this word bi-metallic bi means two you know it ok metallic strip so what we do is this is strip one and placed above it is strip two ok so clear easy I am kind of giving you a microscopic view wire is not this thick ok sure so these two metallic strips shortly will have different melting points ok so see as there is a series connection I will remain the same clear or not so I square R will generate different heats depending on their own R's right so we design them so that after a certain temperature after a certain temperature this one which is beneath will get melt as it will melt if it has like this is the lower one this is the upper one ok they are suppose connected ok as it melts this one bends down right or not so the circuit will be opened easy yes sir easy yeah got it similar thing you use in tubelite starter at home these days we use CFL and LEDs right but at school at least we have in your classroom also I have seen it's only CFL so when we see cubelites right in tubelite there are two parts two devices like this is the frame we set the tube here all of you guys have witnessed it right you are not that young in the era of tubelite and bugs right so this is a choke coil the bigger box and this one smaller is a starter even the starter is made of biometallic strip ok sure yes sir easy ok clear ok the chapter is there was I clear yes sir sure is there any doubt remaining no sir no sir sorry for the delay but the electricity videos ok which was the last chapter and previous year solved questions numerical specially also complex conceptual questions are already recorded in a day or two I promise that I will upload ok dear sure there will be there on youtube sir there will be there on youtube ok the links will be shared with you ok we will try to create a play playlist so that it will be accessible in just a click ok and yes sure similar way the electricity videos electric effects of electric current videos ok and whatever chapters Rohit has done they will follow the same course ok yes sir sure dear ok if there are any doubt you can easily reach out ok feel free whenever you are reading and you get a doubt don't wait for the day to come ok you can send it anytime so clear we will always like try to clear that as soon as possible ok whoever will see it may be your own classmate ok sure who may solve it out here yes sir thank you sir good day bye happy republic day ok oh yeah happy republic day sir there was some connection problem in the middle so I had gone out so sorry about that no not a problem bye