for W this chapter is all about calamities you can say lightning we'll talk about earthquakes but you know these things which we are very much scared of we are going to study it there's a lot of signs in it and that's why today let's understand them the way science should be right let's figure out the science behind them and that's why kids welcome to the one short session of some natural phenomena everybody good evening good evening how are you I'm good yeah I'm good how are you you tell me first and I'll take your doubt let me start come on good evening everybody welcome welcome Oran an Santos Lana soale S Abida very good very good so everybody this chapter is something which I have seen a lot of people think sir I don't think it's an important chapter do you feel that some natural phenomena is not that important the way we have like light like we have chemical effect like those are good chapters sir they are scientific chapter this chapter is all about lightning what to do in earthquakes how to prevent yourself from lightning um all of this right do you think this is not a good important chapter it's very important l i i I'll take down don't worry let me start now come on H abhas for 6 to8 your session has been rescheduled to Monday we don't want both of the 91 and 628 to get clashed so your plan is getting refined and we'll meet on Monday don't worry and important listen to me let me clarify something very important to you this chapter has two important Concepts two very important Concepts one is lightning so we we'll understand everything behind lightning why lightning occurs what what are charges how charge transfer happens how things get charged and when this charge transfers from one body to another and when this happens then what will happen and so all of this is connected to lightning so we'll think and we'll understand we'll explore everything behind lightning that is one right second precautions very important we'll talk about precautions right third we'll go to earthquakes why do we have earthquakes and how to prevent yourself how to safeguard yourself when earthquakes happen right could this all will understand today are you ready yes come on come on are you ready an unexpected you don't know when there's going be when there's going to be a fault or when there's be going to be a tectonic plate movement you can't figure out that's why good evening yes are you ready come on Sarah shall we start because before starting I have a condition I want want Jo to be high I want you to be attentive I want like button to be pressed very important that thumbs up is very important here see one shot I don't mind do you know there is already a oneshot on your 628 Channel why am I doing it again there is already a oneshot session there's actually two oneshot sessions previously we broke this chapter into two parts right if you if you have been regular you would know chapter already why am I doing it again we don't do it yes so that in one session you should be able to complete the whole chapter ion and let's understand [Music] lightning Lana not all objects conductors May it's difficult but yes insulators me it's easy all right let's begin have you ever experienced this I mean I this I did this when I was a kid up to right so have you ever experienced it you are combing your hair and suddenly you feel like you bring it close to pieces of paper and the Paper Bits get attracted you might be doing it in your in your classroom also you take a plastic scale you do what right nowadays I will do right so then if you bring it near to the plastic oh sorry uh Paper Bits they will get attracted you have done this this is a very good starting point to understand lightning yes it's a very good starting point how I'll tell you now there go why is it happening how the comb is attracting the Paper Bits that's the first question and you know what the lightning has a similar trick like the comb and paper yes both are connected how and when we have to understand what is everything made up of what are things around you made up of in one simple word and I'm not going too deep I'm not saying going to qus bons ESS B particles I'm not saying go what is everything made up of come on atoms very good Cosmic Explorer nice said that very good very good nice so everything is made atoms atoms atoms I mean till our grade as we know it has a center portion which is very heavy it it is made up of protons and neutrons outside May what do we have we have small small particles which are kind of revolving around this Center portion we call them electrons right now this is where the charges come into picture charge charge is a intrinsic property of matter matter property every matter has charge right every matter has charge which type of charge there are two types of charges one is the negative charge h AK negative charge we call it it is made up of you can say electrons which particle gives you negative charge we have just said it netive charge you figured out you had to give a name you gave negative to electron right so negative is two electrons positive is two protons right very good sir very good so two types of charges negative and positive clear has Happ by rubbing yes you right my name is no one okay nice correct now what are the properties of charge see when you rub two objects and especially if you notice two insulators it could be your hairs and a comb it could be a balloon and a cloth it could be uh uh eonite rod and silk right most of them are insulators when you rub two objects what happens every atom is made up of you told me electron outside protons inside when you rub two bodies H some of the atoms they gain energy especially who the electrons electrons are like those small kids of the house who are just looking for a reason to run outside like you guys sometimes I know right so electrons when you rub two things when you rub your both the hands you feel hot right this hotness this is energy and electrons gain this energy and they jump to other body and when this imbalance is created that's how bodies get charged normally Char right correct normally you and me we are not charged we are not charged then sir how bodies get charged when electrons gain energy so that they can jump from one body to another that's how things get charged here if you take two balloons made up of same material if you take a cloth let's say you take a buen cloth or let's say a silk cloth you rub both the balloons what do you see you will see both the balloons start to move away from each other right you see both the balloons are repelling each other right H Lana one shot of light tell me in the comment section we'll see we'll see yes IGN if I just keep taking all your name you listen to me you ask the doubt I'll manage fine now when you rub both the balloons with the same cloth M sir Doo material are same so whatever charge the balloon gets over here same charge balloon will get over here right both the balloons are getting same charge and they're getting repelled that is a good understanding like charges they don't like each other like charges they repel like charges they say when they look at each other go away right so two like charges they don't like each other they're repel right so like charges repel and there is more that is going then meets the ey come on properties of charge now let's say you have this thing you rub your pencil with plastic sheet and you keep it in a glass then you rub your balloon with let's say separate cloth right you will see that both of them are attracting when things are rubbed with different different bodies their charges are also different or different charges they Attract it is similar to the magnetic poles in magnet North Pole likes South Pole South Pole likes North Pole but North does not like North and South does not like South like poles repel like charges repel unlike poles attract unlike charges attract same thing unlike charges attract now if you see when the Paper Bits were getting attracted to your comb right interesting magnetic force H magnetic force we have done class six fun with magnets that very easy chapter right h s that I'll do PKA don't worry correct it will attract so charging by friction we have three types of charging charging by by friction so wherever you are seeing this rubbing right think about it when you rub your hands become hot because of because of friction and because of roughness so one is charging by friction wherever you rub things no that is charging by friction charging by conduction charging by conduction where you touch and something gets charged right that is charging by conduction where touch is required charging by induction is where without without even touching you can charge other objects ah right so these are three ways of charging correct yes everybody three ways of charging by friction where you rub things conduction where you touch things induction where you don't even touch things you will bring up some you will bring a positive charge it's a metal sphere all the negative so charging by induction Works something like this let's say you have a positive charge over here right and this is your metal sphere all the negative come over here all the positive come over here now if you connect it to Earth Earth and by the way if you have been following all the Olympiad sessions you would know I explained this in the olymp session sir Earth is like a big big I would say a very hungry body I will take it right ah very good so that's why all the negative things go over here right so that's why this becomes negative correct so this is called as charging by induction is question right three methods of charging we are done charging by friction charging by friction by if a body gets charged means it has some extra charge it could be extra electron it could be deficiency of electron right you tell me something if I say this body is negatively charged which means it has something extra what is ity come on Earth is a huge magnet huge but weak magnet red roses come on don't know you tell me shagun bye H if I tell you this body is negatively charged which what is excess in this it has extra electrons right see naturally all the protons and electrons are equal in a body right but when this imbalance is created when a body gains more electron because of different different methods could be friction could be conduction could be induction right if you charge a body and a body gains more electron the body becomes negatively charged why because now negative charge is more than positive charge right so that's why overall negative charge wins sir so the body gains negative charge why because of excess of electron when I say this body is positively charged does it have something extra what extra does it have when I say this body is positively charged what does it have extra and H and there is a series called as tribo electric series I don't want to teach it to you for ICC I teach and for grade 11th I teach just Google it no after this session tribo electric Series this will tell you when you rub something with what what charge will go over there yes proton electron you know proton is inside the atom the center of the atom if protons get transferred M whole atom is getting transferred but that does not happen so you know when a body is positively charged I told you normally positive and negative are at same level if let's say a body loses electron H I had let's say 10 electron 10 proton and someone took my four electrons now what is happening I have 10 protons and six electrons means I have more positive charge than negative charge so transfer of electron only happen the one body which gains electron become negatively charged the one body which loses electron become positively charged right so I won't say this has gained proton a positively charged body has lost electron yes clear and those were not charged it's a very good point I'm happy yes class 7even play time we had no Olympiad class we had electrolyte multi ideas chemical effect of electric current but we have done this right H so static electricity refers to an imbalance in the electric charges in a body static what is the meaning of static think language wise sir I am static means static means come on Namaste Namaste static means reproduction your language is different I think what is electronic rest good or static means at rest so these are charges which are not moving why because they are on insulator insulators they don't allow charges to move freely conductors do right so conductors El you can say electrons of conductors they are out of their hand so similarly you can say conductors don't have control over their electron but insulators they they put a lot of control over their electron right so electrons cannot move here and there in insulators so you can say if a insulator gets charged by friction conduction or in induction you can say you can say what is happening the charges on that body are there they are at rest static electricity yes H mov an not throughout the body if you if let's say this body is positively charged and you bring this body both are insulator HH you touch it this will become positively charged right but not throughout from the tip the tip will become positively charged not the whole body that's important fine H good good good nice so electrically neutral sweater rub with a balloon charges get rearranged after interaction with the balloon but question is Sir if you give me this pen and you ask me hey can you Det if this body is charged or not come on think about it can you DET if I just give you this pen H I come to you and I give you hold this pen and check if this is charged or not how will you do it yes nice good good good on h l i I'll take care of it B take near hair anug good good that's a that's a nice answer actually what do electronic understand electron body a body is made up of tiny tiny particles called atoms in chemistry you might have read about this no atoms under we have central portion which is proton plus Neutron proton is positively charged Neutron is noncharged H that is the nucleus heavy part around it we have negatively charged particles called electrons which keep on rotating right so that's why this is atom correct H very good huh nice H buy a silk clothing okay what if there was a technical instrument for this ah and you know what there is we call this instrument as electroscope right spectroscope checks Spectrum electroscope checks how much electricity or you can say static electricity is there right an electroscope is a device that is used to detect the presence of electric charge on a body sir how does it work first of all let me tell you how it is made up of very simple starting me on the top you have a metal disc and actually you know what something you can make and I'll tell you how don't worry metal disc is on the top we have insulated plug then there's a brass Rod there's a glass jar and there's a gold leaf we have gold leaf think about it you tear your aluminium foil make it a a v-shaped leaf and you put it h yes simp let's understand how does electroscope work now you tell me normally everybody is positively charged negatively charged or neutral I mean normally every body is positively charged negatively charged or neutral come on yes SCH andine aluminium can also be used right so that's why we only said electroscope what is seismograph Rahul it will come in this very session don't worry neutral everybody is neutral yeah and see I'll tell you something if you have a if you have a plastic ball if you have a plastic ball right and you bring a rod which is let's say positively charged H right so this plastic wall will have a very very very tiny polar polariz ation polarization you can say few electrons will come this side few positive will go this side why sir because positive repels positive and positive attracts negative right to electron why because insulator insulator will not allow it electron to just run right so insulator keeps control over electrons right but this is plastic if this is a metal ball metal ball electrons are free must so when you bring a positively charged Rod charged Rod near the metal ball you know what happens all the negative charge it comes on this side why because negative is get attracted to the positive charge positive rod electr and this positive charge will repel what positive charge right on that side we have deficiency of electron if let's say you have equal positive negative if all the negative runs over here we have deficiency of electron over here this is positive charge now so this becomes positively charged right H working and explaining but I'm going towards that only it is that LEF real gold auh Kevin yeah very thin say I'm telling you brass Rod brass is a is a type of material no very good this is clear tell me yes or no yes or no is this clear I'm telling you this is something which is very easy right is this clear right is an intrinsic property of a body that's it that's it charge special property of body correct now when you bring a charge body near to the near to the the disk of the electroscope sir my balloon is negatively charged so this negatively charged balloon if you bring it close if you bring it close then let me ask you if you bring it close look at this animation first guys before this I want you to look at this animation tell me in this animation we are not touching the balloon we are not touching the balloon right correct yes what are ions my word ions chemical effect elri current I just taught this repel good see I'm saying if you have this disc right this is your brass rod and then at the bottom you have your two gold leaves like this fine you have two gold leaves now when you bring a body which is let's say negatively charged what will happen you are not touching it so what will happen sir all the positive charge will run towards the top why because of the negative charge both like each other what will happen about negative charge I don't like this guy right so negative charge will all all start to deposit over here now you tell me these are two leaves H these are two leaves and both are negatively charged what will happen they will they will spread this is negative this is negative they want to go away from each other so they will spread like this right right now this is about how if you don't touch repel very good now if you touch your balloon your balloon was negatively charged and your negatively charged balloon came and touched the gold leaf electroscope now your leaves are negatively charged done your leaves are negatively charged in the previous case if you remember I told you all the positive is here and all the negatives here but the moment the moment you remove the balloon the moment you remove the balloon you know what happens sir electroscope becomes normal why electroscope was neutral only charges see until unless you touch the balloon no extra charge will come and go right it was H what was happening so all the positive went on top all the negative went on bottom that is why the leaves got spread correct balloon if you take the balloon away what will happen sir it is neutral only all the charges will get distributed and they will say right yes h what about positively charge uhhuh you can do same thing with positively charged if you touch a positively charged balloon with this thing the electroscope will become positive charge right correct so that is why if your body is charged listen to me very carefully I explained you a little deeper first thing but important thing if the body is charged and you touch that body with the electroscope the leaves will spread leaves will spread leaves right but it was still working yeah I told you know insulators charging by friction is is best with insulators uhuh water can be charged or not sh I'll give you an experiment for this right everybody is this clear what is the test to check if a body is charged or not sir I will take my body I will touch it on the metal disk of the electroscope and two leaves will spread that is your test clear yes what is distillation himansu distillation somewhere else you boil water you collect the vapor you condense it that is installation now how to make a simple electroscope it's a very famous thumbnail picture our guys are very proud of it uh yes H this is what happen happens when you touch uh a Vandy grab generator I will not go into that right now but you know what recently last year I did this session where I taught the students how to make their own electroscope right so this is something you can go ahead and check it out this is the thumbnail picture of that session right H yeah yeah this is me only I know correct oh no no can liquids be charged Oto girl liquids get charge no when you give ions to them right ions are what charge only liquids May who moves ions solids May who moves electrons as simple as that right everybody activity time if you bring a charge balloon very close to your empty cold drink can your can will be attracted your can will become attracted towards your balloon it will move in the direction of your balloon you can try it out and there are lot of videos on YouTube about this right similarly when when you bring a charged balloon closer to water closer to water the water will get deflected towards the balloon that is also an activity you can try and everybody this is for you to explore these things right easy you explore them and tell me in the comment section did it work for you or not charge nice thank you can we just sound light ooh and what do you need a body should have atom does light have atoms no is gas is charged rul gas can be gas can be ionized I would say nice Nia thank you first one work not understand kumal if you listen very carefully you will understand right I'm not sure if the language is the problem or it is the concepts right but just know I'm telling you these are activities I want you to try at your home because you what do you need yeah you need balloon and what else you take your balloon and now it is the winter season that is best Winters May everything works very nice why because winter is a dry season and dry season me all this static electricity it works very nice so take your balloon rub it with your sweater and bring it close to water tap what you will see tap will it will deflect you rub your balloon bring it close to the can can will start moving right so all of this is fine sir we started with lightning h do you remember our whole discussion started with lightning and we are what are we doing right now sir we are rubbing balloons plastic right we are moving cans why are we studying this yes very serious about this chapter nice they should be there is only summer season oh K nice yes Kevin I'm saying I'll I'll tell you how to make a body charge I'm joking H I know H very good and listen to me now see everybody let me just give you a quick repap recap what we have learned till now we started with what is lightning and why does it happen right we said if you have tried those activities of where you rub a scale a plastic comb in your hairs and bring it close to the plastic sorry paper the paper gets attracted com and all of you have done it there is a good clear there's a good relationship right which means it's about static electricity if you rub two bodies right bodies can be charged why because bodies are made up of atoms and atoms have charges normally they are equal but by rubbing by doing something like charging by friction charging by conduction charging by induction using these three techniques you can charge a body when a body gets charged now it will show its effects right unlike charges they attract each other like charges they don't like each other they repel and all of this whatever you are doing this is the this is the consequence of whatever we have learned the device which can detect charge the device which can detect if a body is charged it is electroscope let me give you a statement and you tell me true or false electroscope can tell you how much charge is there on a body true or false yes ah Aida nice it's capacitive sensor that's true come on true or false electroscope can measure how much charge is there on a body yes or no true true true false false false ah yes lightning happens to charge this is false electroscope can only detect if a body is charged or not you have to take the charged body touch it and if the leaves get spread it means the body is charged what electroscope cannot tell you it cannot tell you how much charge is there on the body let me give one more statement electroscope can tell you what kind of charge is there on the body answer is false if you touch a positively charged body to electroscope the result will be leaves spreading you will say body is charged if you bring a negatively charged body and touch it to the electroscope what will happen sir same thing so you have it will tell you if a body is charged or not what kind of charge it will not tell you how much charge it will not tell you yes these are small small questions which can come so I'm telling you I hope you understood come on everybody Lana B if you say this again and again nothing will happen see H I want you to write a comment section so team can have a look but if a team gets irritated they will might block you and they will not do it again right so that's why it's a complete open Stam telling you you write it in the comment section the team will have a look and if they feel this is Justified they will do it okay fine very good repulsion is more aha then body will go away more for class A don't worry yes again whatever I told you body as atoms it can be charged using three methods friction conduction induction right which device can detect the charge it is the electroscope it will not tell you how much charge it will not tell you what kind of charge unlike charges attract like charges repel this is everything we have learned this is all you have to learn apart from that nothing all very good and you know there was there was a person American dollar you might have seen in movies at least in American dollar notes there is a picture of someone who is he come on it is H yes it is the picture of Benjamin Franklin Now Benjamin Franklin although he was a politician but he was very much interested into science and you might have heard the story he tried he always suspected that that lightning is charge he thought I will catch this lightning into my bottle right sir Benjamin Franklin he thought I will catch the lightning into my bottle so what he did he took a kite made up of like it had some metallic threads there was a thread of metal and he started flying his kite in the sky hoping the lightning will fall on the kite and this lightning because of his charge will flow through the wire and he will store it into his container this was his thought process but luckily the lightning did not strike his kite but he still got a mild shock you know all the wires correct yes so it means yes there was charge in lightning but luckily it did not strike his kite right what do you think what would have happened if the lightning would have struck the kite yes what do you think what would have happened if lightning would have struck the kite yes how can lightning be stored Hamad charge can be stored means lightning can also be stored yes yes as doubt ah rip luckily the lightning did not strike his guite but you know where the lightning strike stried after a few months there was one more one more guy who did the same experiment I don't remember the name but lightning struck his guide and he died on the spot so lightning is dangerous something which is not to be played with but this is something which tells us that lightning has charge clouds have charge and this lightning which you see it is the charges flowing and you know I would say unimaginable amount of char charge flowing you can think about it like this right so that's why lightning has charge let's think about we said sir till now whatever we studied it was static electricity but you are telling me Lightning has charge and that charge is Flowing right where does charge flow charge flow current electricity ah person and his helper maybe right what is phenomena PR phenomena means means any uh natural I know I'm struggling to explain you phenomena phomen Something You observe in nature that is called as phenomena ah yes very good George Washington huh very good due to which charge lightning happens ah we'll come to it static electricity versus current electricity if you think about it static was when the charges were not moving current electricity when the charges move okay fine in all your insulators charges were at rest whenever they get charged charge will remain there but in your electricity you know wires all the wires you have in your house you turn a switch on and your fan starts moving right why is it because of of so current what is current rate of flow of charge so it is charges only H correct yes ands Class 7 physics we teach yeah that's true we did this time very good charges are in motion where when current flows in a wire right so in current electricity the only difference is the charges flow correct okay sir but how does the lightning occur take it sir we understood a lot of things yeah we understood about static electricity we learned about charges we learned about flow of charges what is current it's the rate of flow of charge correct H and if you have seen there is a current chapter in your grade right chemical current in seventh you had effects of electric current all of this we talked about current here current flow of charge but lightning what about lightning from where to where are the charges flowing they by important thing your clouds they are made up of Sir they are made up of moisture they are made up of small small bits of ice right all of this is what clouds are made up of now these clouds when air kind of moves across the clouds you can say this can be called as charging by friction you can say a cloud is getting rubbed again and again by air or you can say a cloud is getting rubbed again and again by the neighboring clouds this makes them charged a cloud becomes charged right which means sir Cloud now has two types of charges which are in opposite direction AB so listen to me the charge which is closer to the Earth right it will it will do the same thing which your comb was doing to the paper the comb was asking the paper to come come come come come H same thing the charge in your cloud is asking to the Earth it is asking the charge in the earth to come towards it right so this is what the cloud charge is telling the charge of the earth L Earth is fixed right so what will happen charge from the cloud will be so much that it will have to move towards Earth in sudden jerk and this is what we call as Lightning right so did you understand because of rubbing from the air and the surrounding cloud it becomes charged this charge cloud is passing over the Earth Cloud charge it is passing over the earth below it it finds whatever it finds the cloud wants to become neutral so what will it do whever it will get mocha whereever it will get a chance H wherever This Cloud will get a chance the charge will move towards Earth and this is what is lightning hji yes ah come on come on come on H draw black listen to me what I'm saying is your Cloud let's say becomes charge plus plus plus plus plus minus minus minus minus minus why sir because of you can say all the air moving around it air say the cloud become charged fine now this cloud is moving over the Earth n n wherever This Cloud finds a good chance but it can find let's say a pole or it can find tree all this charge suddenly comes down this is what we call as Lightning right is lightning this process of electric discharge can occur between two or more clouds or between a cloud and the Earth to lightning it is electric discharge only right correct ji everybody lightning and thunderstorm thunderstorm is a storm in which you see lightning and thunder thunder is what hearing right correct so lightning is simple lightning a thunderstorm is where you see right come on good question it's a very important question lightning is caused by the accumulation of charges in the clouds very important thing now question now you tell me something have you ever seen whenever there's a tall building or in your city have you seen any tall buildings building tell me if in your city or whenever you go to let's say uh Mumbai may we have very highrise buildings bangal also we have so have you seen those tall tall buildings correct have you noticed tall buildings have these pointy pointy topsall building fashion is it do you think it is because of looks no no buing oh yes who discovered lightning you can say uho lightning is a natural nobody discovered it yeah prevent from lightning aha good why do tall buildings have these pointed roofs to prevent from lightning there is a red color bub so that airplanes might know there is a building over there second they are pointed why because this is this is saving your building and you from lightning so how let's understand this go if you notice this CH this tip H this pointy thing it is made up of metal and this metal is not just on the top this metal thing goes through the building till the Earth it is going from here then through the building it is going going going and finally it is going inside the earth so why what is lightning sir lightning is electric discharge right lightning it is electric discharge so when this charge falls on this rod and let me tell you let me tell you if there is a cloud This Cloud is charged This Cloud is charged and on the earth there is let's say uh dog uh drawing is very bad okay let's say this is a dog and let's say there is a tree okay let's say there is a tree if lightning gets a choice who do you think is more prone to be struck by lightning yes lightning conductor is used the process of earthing it is connected to the earthing pit yes come on am answer answer tree tree why hey why why why are you saying tree Intuition or there is some logic to it mixed Ah that's true yeah why is tree conducting electricity as such air is also insulator why is air conducting electricity because this difference of charge becomes so much that it breaks the air you can say air it breaks the air and ionizes the air and then it makes a PA you can say the air ionizes and that's how this charge flows right so this lightning has a lot of charge by what what why because it's tall uhhuh good because it's tall and what happens if a building is tall if something is tall it will become polarized so polarize M if you remember I just taught you yeah if you have a metal sphere right and you bring a positive charge body all the negative will go over here all the positive will move over here right H this is called as polarization so when this charge Cloud passes over the Earth it polarizes everything negative negative negative negative positive positive positive doggy is doggy negative negative positive positive but this doggy is at a lower level this tree is at a higher level so if lightning had to choose which negative charge to gain which is easily accessible you can say that this lightning will see which one is easily let's go towards the tree push right correct side so that's why I'm telling you these tall buildings are more prone for the lightning yes electric energy sha yes we can bu always if there is a tall building now it is more prone to be struck by lightning and when you create this pointy Rod when you are just creating this pointy Rod you know what you are doing you are calling the lightning you are in a way calling the lightning you are say hey come to me come to me right so this lightning rod it is pointy it is tall it is kind of attracting the lightning right why is it doing it it will it will help others also discharge it is helpful to others also so what will happen charge of the lightning will pass through this metal metal rod throughout the building and finally will reach to the surface of the Earth Earth is like a very hungry person for charge full Lightning goes to Earth chill yes correct huh abas for class 8th don't worry we'll come to it we'll come to it we are launching it on Monday we want to make it special day for you know that's why don't we get shocked an charge always select a path with less resistance electricity current or you can say charges they always like to flow through a path which has less resistance your conductor this whole lightning W system this whole lightning rod which is going through the building it is made up of metal and metal is like an Express way for charge H charges like to go through metals they don't like to go through insulators insulator lot of jams I like metal conductor why right so that's why charges go through this lightning dood because it's a metal so if you are in the building you will not get be you will not be affected by this charge why because charge is going through the rod charge must right so that's why the process of transfer of charge from a charged object to the Earth is called Earth thing ah right it's called earthing and this earthing you you do for your home appliance also same cheese all the extra charge now you want it to go to earth that is your thing yes just check your building manager do we have a lightning uh conductor on the top excuse me I had a question uh do we have a lightning conductor on the top of the building uh take fine a lightning conductor is a device used to protect buildings from the effect of lightning to take all the charge of the lightning and give it directly to Earth without affecting the building and the residents yes which metal you can say this is copper mostly it is copper be copper plate because copper is a good conductor chapter 13 okay H very good correct everybody listen listen listen to me till here it is clear why lightning happens because clouds get charged H when clouds see anything which is pointy they will fall right all the charges will come towards the Earth this Electric discharge is called lightning simple fine or how to protect your building using a lightning conductor easy till now is it clear nothing happen conductor will take the charge directly it will not affect you relax multi ideas good question so lightning safety outdoors and guys this is a very important question because subjective question we have been seeing it is very commonly asked because it's a very important thing we should know if you you are if you are studying in school we should know how to prict oursel in lightning right lightning right so what to do reduce your height you can say h so you can just bring your level down dos and don'ts if you are outside imagine you are in a open ground H and there's a lot of clouds right so much lightning is happening what to do sit Crouch down with your head between the hands Crouch down right this is called as crouching down with your head between the hand what are you doing you are reducing your height right because lightning it checks for l l right that's what happens come on sorry your question raal n sorry right listen to me second get inside a car why because cars are nowadays made up of fiber bodies and when it is wet no lightning will fall on the car it will through the body of the car will go inside or car so it is made up of leather seats rubers rubber mats under say the car is fully insulated so inside the car you are pretty safe so relax lightning it will not affect yes charge Earth is so big Earth so much electric charge is already flowing and because of this charge inside the earth you have this magnetic poles Earth magm because of charge of the Earth right find shelter in a building not a Kopi kop hey what is a kopy can you you can say these makeshift pandals don't go to these Kopi types item go find shelter in a building fine what to do second what not to do do not stand under an isolated tree what is the meaning imagine if you are in an open field field field there's only one tree it starts to rain and there's a lot of lightning happening let's go under AE it will be safe right do you think tell me yes or no come on I know I know but relax the light will go the current will go straight to the ground no never good I told you I told you who is at risk who is tall right so if you go to this tree it is a tree which is alone in the whole field lightning will see l l l tree and you are sitting under the tree and you will be like roasted marshmallow right so please please don't do not stand under an isolated tree never aart why vising isolated if you are in a forest and there's always trees then it's fine right lightning will see all are same inky pinky py right so if you are in a forest lot of trees are there lightning has no choice right getting my point canop is a Christmas tree kop is that those P thing you have seen no these stalls yes correct H mix use yes P you're right very good to revise very good yes SII welcome welcome now listen to me second avoid High Ground why you should not go to High Ground lightning likes tall things right if you go to height you are a lightning will say come come come let me let me take care of you H so avoid High Ground do not carry an umbrella why sir umbrella normally is made up of that metal umbrella at least the previous one they used to have those metal tips umbrella used to look something like this so this metal is risky by so AG if you see lot of light ing close your umbrella and run for your life right why not isolated your tree Nisha isolated tree because it is in the open field this one tree is at a height it is at risk that's why okay fine clear everybody three things to do and three things not to do when you are outdoor but if you are indoor then what to do yes huh very good lightning safety outdoor right outdoor we have done no no no a second this is not outdoor B this is indoor under avoid electric equipments have you seen this when there's a lot of lightning happening outside right your parents they tell you have you seen this come on number oh thank you have you seen this happening so again inky pinky py very good can we bath with bug mug and bucket in lightning but still still you will turn the water on risky relax avoid electronic equipments why because lightning can fall on electric poles and the sudden current can come and come and dis damage your equipments avoid electric equipment first second unplug the appliances Appliance right so that's why unplug the appliance third stay away from window when there is a lot of lightning happening please please don't go to your window open don't do that stay inside away from window three things this is do electric appliance window fine don't touch that's true don'ts what not to do nobody will say don't take a bath why because like tap water and a tap water is a conductor let's say there is some water tank near your house from where water supply is coming to your place imagine that high tank has got struck by lightning that water supply will have a momentary surge of current right so that's why I'm telling you not take a bath tap water the conductor yes because of impurities hey this to we have done in chemical effect of electric current session watch the session come on do not take a bath do not lean on walls right if you are in your home do not lean on the wall say wall this is my be there might be lightning conductor behind it there might be lightning passing through the wall so stay away from the wall fine hii IDE if there's a lot of pressure it might be possible do not use telephone why telephone if lightning strikes a telephone phone and by the way this is not about mobile huh everybody it is about landline mobile this is about landline nowadays we don't use landline when we were kids nowadays very few people have landlines apart from government offices and your Corporate Offices do not lean on walls wall if lightning has fallen on your building it will pass through the walls so that's why if you are touching the wall you will get a shock so don't lean do not use telephone Q sir landline it has all those wires connection now right so in on that telephone pole telephone booth you can say po if on that pole lightning Falls the lightning will travel through that wire and come to your phone and if you are talking Hani hello right so that's why ah Study Life yes people do it there are companies which are doing it ah guess where are we able to from Windows you should stay Windows now because if you're in your window you are at a height first second third fourth 14th floor you are at a height right so that's why stay up from window safe correct these are don'ts with this we are done with lightning everybody tell me is it clear lightning May there are three four things which are very important first different modes of charging take fine next is what is a charge unlike charges attract like charges repel the device which can detect charge that we have learned what is lightning how does it happen this we have learned then the safety precautions what to do when you are outdoor and what not to do indoor under things to do things not to do these are two very very important things right okay with this we are done with lightning and this was in our previous one chart my first my first session we had done almost 1 hour we'll take another half an hour to complete the next thing lightning clear lightning say tell me everybody I want to see the Jo next time if you have a lightning will you be aware what to do and what not to do yes or no don't worry you have a lot of power power of Common Man Woman boy girl yes hob you can talk with mobile not a problem yes relax everybody fine oh hey what is this it's earthquake I know bad acting but earthquakes how many of you have I mean hopefully not how many of you have experienced an earthquake and see if you are in Delhi up uh utarak in past few months you have experienced earthquake that I know if you are in Bangalore in uh Andra Pradesh odisha you might not have experienced expence earthquake returns me me me me me correct it's a natural disaster in Kashmir oh yes everybody you know what earthquakes are very much possible but there are zones of earthquakes in India if I talk about it it's not every place you can get an earthquake there are few places which are at risk of earthquake and if you have experienced you would know but not all places are at equal risk there are few places which are at higher risk there are few places which are at lower risk in this earthquake while section we will learn about what is earthquake why do they happen how to measure the earthquake but one thing which an was asking is you cannot predict an earthquake this is one thing which is which still we are at fault because Earth fault line you cannot predict you will know that on this fault line earthquake can come anytime but but no idea when right so that's why predicting earthquakes is right now not possible right but we know why they happen right how to safeguard ourself that is very important if you are in between aukamp in Hindi we call earthquake asuk right these are some very important things we'll learn in earthquakes shall we start come on yes so that's why metal things if you take outside yes from Kashmir I knowa all the hill areas are at risk I'll tell you and how to safeguard yourself I tell you don't worry chello hii ah come on all right earthquakes natural disaster these are what they are natural disasters where you don't have a control sir sometimes it happens because of us also that's true but still they happen naturally so we call the earthquakes as natural disasters it is caused due to shaking or trembling of the Earth Earth Quake sudden shaking or trembling of the ground Beneath You Hil Jana right if you have experienced you can't be joking about it because earthquakes are scary earthquakes are deadly if you remember the Nepal earthquake you know how much Devastation it happened if you remember the Japan's earthquake you know how much Devastation happened right earthquakes are not a joke and that's why it's serious so we should learn about it correct H yes ah very good earthquake they are natural disasters yes sir because Earth shakes Earth shakes sir Earth we live right what happens when earthquakes come have you seen it these are few of the images telling you a lot of story about what happens in earthquakes lives are lost they lose their family members brothers sisters son wives husbands parents earthquakes are a disaster right so that's why but why do they happen earthquake tell me come on see as people of science you are studying it right now so that tomorrow when you grow up maybe maybe you would like to explore Maybe you would like to come up with a solution of how to predict earthquakes yes movement of tectonic plates that's true now what is a tectonic plate it is caused by a disturbance deep inside the Earth crust you can think about it you know what Earth crust the land on which you are living you know what you are not living on a solid land you are like sitting on a thermacol floating on water think about it you are like sitting on a thermall floating on water your Earth this whole land is like a thermacol floating over water simply so is it really water no that's not water that's the liquid molten metal in the Earth right but your land is kind of floating over it it's like different different plates they are floating over this liquid molten metal yes correct floating on magma very good H yes so that's why what is Earth made up of Sir the outside area where we live is called the crust I say if you order pizza what do you say give me thin crust I want stuffed crust crust M upper layer outer layer right mantle mantle is the layer next to the Earth the next to the crust crust mantle semi liquid outer core interior of the earth is called the outer core then we have inner core if you go beyond crust and crust it is it is quite quite huge right so outer core then inner core so Earth from inside is liquid yeah that's true now question is what is the cause of an earthquake it is caused by a disturbance deep inside the Earth crust this is what I told you and the crust of the earth is in the form of fragments which are known as plates I told you it's not like earth is made up of land which is one body cing it is like a covering which is in Parts this covering is in parts and we call these different different parts as plates imagine two thermacol plates floating on water right now what is the cause of earthquake when these two plates interact the continual motion and collision of the plates with each other it causes earthquake yes very good Sunil nice uh the Krishna it was in thousands of Kelvin if I remember I'm not very sure class class it's not Crush it's crushed m styo all right Hindi ex all right come on huh very good there I told you that Earth is not a solid thing right it's not one plate it's like fragments and when these fragments are floating over this magma magma s liquid by so you can say crust is kind of floating over the magma when these two plates are floating there are chances they will come together and do this as I was they will come or they can do this thing right so they can brush past each other or Collision can happen AB Soo you are living on these plates if the plates below you they are colliding boom whatever you have built it is gone to dust and that's how we realize no we feel as humans we are so powerful but nature is much more powerful than us right right it's like liquid correct ah screen is not clear change the video settings go to Advanced and change it to 720p yes they so it can either brush past brushing past say or folding M sir folding means like this this is called as folding right and all your mountains are caused because of folding yes seismic waves the Tremors produce waves on the surface of the Earth and these are called seasic waves think about it when uh uh uh uh uh uh any of you play cricket cricket does anyone play cricket when you hit a ball with the bat do you feel sensation in your hand yes crust crust crust come on me me me H when you hit a ball with a bat do you feel sens s in your hand do you feel do you feel sensation yes correct ah very gly Cricket very good H why is it happening see the ball struck over here Ball but you are able to feel it over here why because this vibration spreads and this vibration spreads similar kind of a thing happens in the earthquake as well inside the crust Point P you can say maybe brushing happened maybe folding happened again when this happens the effect will be only over there throughout the body you will feel Sensations right these Sensations are called as waves the name is seismic waves everybody very important now the name is seasic waves H correct very good trimmers produce waves on the surface of the Earth these are called seismic waves these waves from the point of striking cion sismic waves they spread out and that's how the earthquake spreads out earthquake but you were able to feel sensation in utarak in up in Delhi H so sir earthquake but I am sitting thousands of kilometer away I felt it why because waves are traveling throughout the crust correct H yes magma is not cooling down the because it is in so much pressure and when you apply a lot of pressure things get heated up and that's why it's not cooling down correct H very good now AB the boundaries of the plates are the weak zones you have different different plates now the boundaries of the plates are the weak zones where earthquakes are more likely to occur I told you scientists can predict where earthquake might come hey have you seen that movie movie San Andreas yes have you seen that movie Dwayne Johnson a similar looking fellow dashing guy uh right so have you seen that movie right it was all about fault lines I know are Quake can come but when I don't know right H near Himalayas oh nice very good Hanah yes hello hello hello hello welcome welcome H tectonic plates move 2012 yes you're right correct the weak zones are also called as seismic or fault zones so all these weak zones now we call them seismic zones means they are prone to get the earthquake earthquake what is the map of an earthquake in the earth wherever the earthquake arises it is called the focus everybody these terms are important by these are important terms the place where everything started it is called the focus H and if whenever you hear about the news whenever you hear about the news you will you will hear about a word called as welcoming to this rich scale you might have heard that earthquake happened near uh near pagar earthquake happened near dula earthquake happened near Nepal and the epicenter was this particular place H right epicenter so inside the Earth where earthquake originates that is focus but the point on the surface of the Earth just above Focus surface right that point is called as epicenter right so these are important important terms the origin of the earthquake inside the Earth is the focus and on the surface of the Earth just above the focus point is called as epicenter clear very good epicenter epicenter clear Focus white tonic plates move sketch imagine no if you have two thermacol sitting on water do you think they will just keep sitting no right they will keep moving slowly slowly here and there here and there and they might strike same thing is happening with the Earth correct H yes very good it's okay it's okay not a problem my dear good correct epicenter and focus two important things and from the focus keeping it as a center the seismic waves originate like this right and these seismic waves is what causes Quakes because they they travel and the farther they are from the epicenter the weaker is the earthquake earthquake right there at the Epic Center earthquake was very high oh it was very very very devastating right but at my place I'm thousands of kilometer away I felt a Min minor earthquake H so these waves become weak as they go far and Far from the epicenter right so that's why these seismic waves are what causes earthquake h yes everybody till here it's fine epicenter we have learned Focus we have learned we have learned about seismic waves fine why earthquakes happen because Earth crust is not a solid thing throughout it's in fragments these weaker parts are called as fault zones or seismic zones and these tectonic plates they can brush they can fold and this is what causes earthquakes clear how Earth how last last long usually it's few seconds because few seconds may it has done the damage yes H earthquake I will tell you loudest sound because of earthquake earthquake in history there have been many scale this is important what are other causes of earthquake sir you told me because we are sitting on tectonic plates and these plates move and that's why we can have earthquake is there any other reason earthquakes can happen volcanic eruption explosion of hot gases when volcanic eruption happens no right the nearby places they will feel Tremors they will feel the earthquake so in volcanic eruption what happens boom sudden lava dis placement Under the Volcano disturbance is small intensity High near the volcano volcano eruption these are another natural phenomena devastating and I'll tell you can somebody guess what is the loudest sound ever heard on the earth in history loudest sound ever heard on the earth yes iron plus magnet iron plus magnet see magnet comes near to iron it will Attract it and iron becomes a magnet yes I SS o lad aush the sessions which we have done we'll try to do more but volcano good mount ktoa mount ktoa when it exploded when it erupted the sound was so loud sound earth right so this is the loudest sound ever heard on Earth it was of a Volcan IC eruption so these are not lightly taking things this causes earthquakes this is one of the reasons next anthropogenic factors because of human beings earthquake yes if you remember right now there was this UT Kashi tunnel thing do you remember types of rock can lightning happen in volcanoes or it needs charge particles but when volcano erupt there are few charges yes correct but see anthropogenic factors these are the man-made factors humans made factors so when you mine a lot when you mine mining why to get nutrients to get minerals right so if the Earth is weak at some point and you keep drilling it what will happen it will give up it will become weak so this is one of the reason the earthquakes can happen mining is one reason collapse of mining pass can trigger earthquakes right if you create a mining pass and suddenly it collapses land it will go like boom right so that's why second Rock blasting when you mine it's one way in which you make way right now Rock blasting blasting using explosives can lead to small earthquakes so these are two factors which are caused by us but this is not the all there are other things nuclear explosions yes dog whistle blows how long I told you know it's usually few seconds only yes come on HH difference between Tech ocean see the plates which are below ocean we call them oceanic plates the normal plates which are just above land we call them tectonic plates H yes come on 41 workers they have been saved now that's a good thing H yes third factor which is man-made is nuclear explosions see nuclear explosions are so devastating they are so huge they create earthquakes nuclear explosion asass earthquake AA why because the Earth will shatter because of the blast right so that's why dams and reservoirs this is important can you tell me sir why dams cause uh earthquakes to create a dam see normally a river is Flowing everybody listen to me very carefully everybody time pass how dams can cause earthquakes do you do you have any idea I'll tell you but do you have any idea Dam earthquake come on yes it came name in Nagasaki you're right it is artificial it is because of human activity yes come on come on come on open himim H you're right natural why do you think dams can be one reason of earthquake any idea pressure of water good yeah raal I love this answer nice logical reasoning we have done so many things Force weight aha good listen to me there go normally what is a Dam dam sir there is a flowing water listen very carefully there is flowing water P must you stop that water now what will happen the water which was flowing nicely it will build up rise rise rise rise rise rise rise rise so first thing happened here what this the layer of the earth on which this River was flowing this layer was not meant sometimes this layer was not meant to sustain so much weight of the water if River was flowing it was all fine when you block and the river now rises in height so now this layer of Earth is able to is going to sustain this much water previously it was only this much water this layer of Earth has to withheld H this layer of Earth has to kind of support so much weight of water one second thing what happens in Dam sir in Dam we release water suddenly we release water from much height is let's say this is your Dam gate from here water is Flowing like this H if water is Flowing like this and this water is falling again and again and again and again at this one spot imagine you are hammering a bar do bar three bar bar five six seven eight and you keep hammering always this thing will become weak now H right so when this water keeps on falling again and again and again at the almost at the same spot the spot becomes weak and this can result into earthquakes yes getting my getting my point everybody it is slightly difficult to imagine but this is something I explain my students normally because it will make you remember things sir blasting Mining and Blasting third sir third nuclear explosion dams these are four anthropological factors or multi ideas a river flows you block the river and you let the river rise in level suddenly right so this land was not built it was never meant to withheld so much water second when the water falls with so much force again and again at the same spot spot will become weak it will become weak it will break sometime fine meteor strikes yes that's true but that is not anthropological Factor right now next question in charge you ask this question can I measure the charge I told you you can detect the charge but here you can measure the charge how can we measure the intensity of an earthquake measure that is a good question using a cograph this is a device which will tell you how intense was the earthquake now seismograph is the device H or scale the device is seismograph whatever it plots this reading and this reading is kept or measured using a scale called as richer scale RoR scale RoR scale we call it RoR scale right so magnitude of earthquake this is a very important thing RoR scale question listen to me RoR scale is very important it is a measure of the strength of earthquakes developed by Charles Francis Victor in 1935 each increase of one unit on the scale represents a 10 fold increase in the magnitude of earthquake sir 4 3 4 five uh it's okay I mean it will scare you but it will not be devastating Beyond five six seven oh sir very very difficult above seven deadly devastating very destructive above eight oh my God everything is gone above nine we don't experience but if this comes the day it comes you will see the Earth to be flat yes come on so why difference we only went from 5 to 9 only four step important thing listen to me important thing is if you are a dictor scale five oh or wait I'll come to this right and I'll come to this how how this is divided don't worry if you are at number five and if you compare it with number eight how much unit difference is there sir five 6 7 8 H right above five how much you went sir five about six 7 8 every step but 10 to the power of that step 5 to6 is 10 times stronger 5 to7 is 100 times stronger 5 to8 is 1,000 times stronger 5 to9 is 10,000 times stronger and that is why each step increases the intensity so much getting my point focus focus ah yes so that's why this is why RoR scale above six it's destructive above seven very destructive above eight above nine everything is flat nothing survives that's true India's seismic zones everybody I want you to focus these are the India's seismic zones Northeast the complete Northeast apart from that Nepal uh up wer area utarak Kashmir these are red zones Gujarat if you remember there was a there was earthquake in BJ right very deadly right and here Andaman and nicobar Islands so all of these are zone five means they they have highest probability of getting an earthquake they are at very very risk K Jammu Kashmir yes so all these red ones are the zone of highest earthquake danger zone four orange zones yes almost paur up Delhi utarak right mad Pradesh to slight bit of Mumbai slight bit right so all this is is zone four zone three is moderate zone three you can say your Karnataka is over here so mostly Bangalore is normally safe you can make high-rise buildings zone two is the least active ones but least active it them white right so that's why these are all the danger zones up can you tell me in which zone you are lying everybody in the chat look at this map and you tell me in which zone you are lying ji yes or no the map is in front of you you tell me in which zone are you lying H yes rud tell me come on zone two zone two highest or says highest zone four zone five Kashmir five two two high to moderate five yes yanii this is something sir I don't have a control right now whenever it it will come it will come you cannot do anything can all the people from Red zones they get scared and start running towards all these zones no sir that is my homeland that is my motherland I will not leave it no no matter what happens but you should learn ways in which you can Safeguard yourself because earthquakes are destructive if you have seen documentaries if you have read the news buildings collapse Landslide happen fire happens flash floods happen loss of property tsunami can come because of earthquake if earthquake happens in the ocean you will get a tsunami rise and fall of ground surface interruption in communication systems this is important we all should know what can be consequence of earthquakes this can be asked directly safety measures when earthquakes happen do not panic if you panic right so that's why do not use the elevator use the stairs if earthquakes happens run from the stairs stay away from potentially dangerous objects m c say all the knives and everything so that when something Falls it should not fall on you right potentially dangerous itams be safe right ah cover your head and neck what is the most fragile part of your body body let's say if you if somebody gives you an option body head right brain correct right so that's why I'm saying this head is very important right come H correct because a injury on the head it's fatal right so cover your head and neck G or that's very important next stay away from utility vires Q when earthquakes happen the ties can break down and current can just spread here and there right do not stand at a doorway the doorways are weak areas by it was a complete wall H normally a wall is built like this it is solid but when you build a door right your wall becomes weak wall That's why do not stand in the doorway get under a desk and hold on Q if something Falls at least it will fall on the desk first so desk will kind of work as a cushion absorber right it will work as a cushion drive to a clear area and avoid Bridges Bridge avoid bridges are on earth and bridges can fall so all these are important safety tips yes reflection phomen reflection natur phen lightning earthquake two things reflection we have learned in light chapter yes loss of lives are caused so everybody what have we learned in today's session it was a very important session and I I hope I hope you learned it properly electric charges electron Neutron proton like charges repel unlike charges attract charging by friction charge Separation by induction Earth we learned about all this right parts of electroscope yes we said testing if a body is charged using electroscope metal leaves they repel if a body is not charged nothing will happen it will right lightning how lightning happens what is lightning conductor we learned about causes of earthquakes right Collision brushing past map of earthquake cisor graph RoR scale right now you will ask me for notes right we have learned so much do you believe it in this one chapter there is so much content yes feeling feeling it do you think a good notes will be helpful to you yes or no hii should we run or stay under table MLB dreamer if you can run and go out in the open that is best if you cannot go under the table that is very important H yes we learn so much correct H that is why this is something people who know you know people who don't know I'm going to tell you once again this is grade 8th chapter is some natural phenomena learn is all the learn Journeys are there all the important videos are there you can check it out not a problem but after couple of videos if you like it you can buy it active learn is active revise May summary and this this is all the notes I want to give you why I'm asking you for these notes notes May the best thing if you are revising from these notes how does lightning occur I forget bookmark it if you go forward precaution during thunderstorm sir this is very very important I forget it book Mark It Go chapter summar it's all there it is good for revision as well important question may if you go you will have all the important questions your ncrt questions Exemplar questions check all these out is a free feature that's why I'm telling you right all this is a free feature if you go in your bookmark section whatever you bookmarked it will be there so basically you have your notes which are personalized to you notes whatever you have bookmarked it will be there in the app for you so please please go ahead at least use this free feature I'm not saying you go and buy if you like it you will buy it that is fine I'm telling you from a teacher perspective how you can use these features which are available to everybody use notes it will help you out and you can bookmark things that's a very good feature question fine everybody if you learn something new go ahead check the BYU Learning app it is there in the description click on the link or session fine why do earthquakes occur prian you are late I I covered it in the session right go ahead check it out and everybody check out these notes and check out the 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