 Good evening guys. So in the very same chain of the revisions which we the Sandham family are having with you in parallel for the respective 10th grade exam. Okay so today is the lecture for physics. I'm Ankur I'll be assisting you in order to clarify now which have a quick revision on the lines of the chapter electricity. Okay now on the screen you can easily see that there is a list of subjects which we are going to do listed. Right or not? Why mama will bring you a book? You have got your own legs crawl or walk whatever you can and get that book. So 631 you are asking for the book and I don't think so you'll be in need of the book throughout the lecture. So tricking up the lecture yes there are topics like electric current and it's how it is how it flows in a circuit. Electric potential and potential difference which is way more important than current. Okay then yes circuit diagram because while walking through the previous year asked question they have very consistently asked to draw a circuit with some given number of like circuit parameters connected resistance switches and all that. So I'll be introducing with them parallely I'll be also introducing you with the logic symbols of resistance bulb E and all that. Okay then comes the Ohm's law yes very important if at all a numerical will come from this chapter it will primarily from Ohm's law and then from few other places great thank you nice art and nice removal thank you very much. Then proceeding back like proceeding back to Ohm's law so Ohm's law will have they have question theoretical question how to verify Ohm's law. Okay then factors on which the resistance of a conductor depends yes there is a good possibility of a numerical for falling from this to okay combination of resistance series parallel and more complexing the same thing then comes the heating effect of electric current not very high amount or very consistent questions have fallen from this and it's like frankly speaking from while looking into the past five years papers okay hardly any questions have walked in from this vertical but then too as there is a topic mentioned in the CBSC let's cover it okay so it really doesn't mean it really doesn't mean what that you should skip the topic clear so then comes the last topic electric power yes consistently no audio Aditya Veda and Ragh and others can you guys hear me very easily we have so okay so who is our dear friend who is not having that audio people to produce no audio please check your system because there are dear friends of mine who can easily hear me yeah the chances line right away or an end quickly but that's not a CBSC approach right comprehensively I guess so great so you guys who don't have the this is overwriting and that is also not allowed in CBSC research now no problem so back to the scene what I'm saying is you guys those who have seen re-login that's the best and most simple way there are some ground rule is the Sharpa generally talks about don't panic relax firstly because others can hear if there would have been any issue from my end the scene would have been that that other friends will also like instead of the inbox being filled by yes it would have been filled by no right so the yes signifies that okay my end is oh Prisha great sorry very idiot I am should it should it please please please can you help this thing out okay because I'll meanwhile be having conversation with them okay consider them them your dear friends okay and write them in a formal way not in an informal way okay so help them out please re-login please generally what happens is when others are giving lecture I take care of the back end and support and all you know is there so no problem yes really no one there now thank you the shit ish so these are the topics on a wide note we have to cover okay now looking at each topic one by one for the synoptic for a very last-minute clarification of everything and then we will hit back for the questions will that be helping you out thank you shit ish so topic one electric current so yes primarily what is electric current the flow of charge is called electric current right or not it is denoted by a letter I and by formula it is rate of flow of charge the unit of current is ampere where the unit of charge being coulomb I should write a capital C because it's the name of a person okay scientist clear and unit of time being seconds so coulomb per second is ampere when we talk about charge fundamentally charge is any set of complete electrons n belongs to integers positive or negative number of electrons that means excess or deficiency and E stands for the electronic charge okay which is fundamentally 1.6 into 10 to the power minus 9 and negative integer I don't know I'll repeat q is a set of any set of integral number of job electrons okay the value of fundamental into 10 to the power minus 19 coulomb great thank you okay so on a wider note the same current which is being asked repeatedly in CBC on a wider note the same current I can be written as number of electrons per unit time got it sure exists a reason as you all know there exists a reason for flow of or charge clear and that reason is our next topic that is the potential difference that is the potential difference okay and voltage electric potential and potential difference so voltage is what the general term we use for potential difference the unit is volts okay so now voltage at one location depends on the number of charge and their density this till date is never asked in CBC but because I felt looking at the basic introduction of current so they might lead up to the basic introduction of charge voltage so what is the basic introduction of voltage voltage is the charge density at a given yeah it doesn't just mean that in a big room hundred electrons are there okay they for example at the tip of your pen and electrons are there then the tip of the pen will be at a higher potential as compared to the big room why because we just don't talk about the number of charges we do talk about the charge density and that's what into it the the intuition of voltage is the charge at a given location got it so potential difference is voltage okay charge generally flows from higher potential and that is what we do when we attach a battery to a given circuit okay the two terminals are potential difference the charge starts from those two other yes please sir Gokul and Trisha want you to repeat that the starting of the world's part again okay thank you very much thank you very much so I'll repeat it voltage okay sure what is voltage so as I was introducing you with the current current is the flow of charge from one location to another but why will charge move what makes the charge move there has there should exist something which should break the energy of charge and that is what we call the potential potential difference okay charge flows from higher potential to lower potential charge flows from higher potential to lower potential so what is the intuition of potential potential means the density charge at a given location I was taking example there is a room in which there are 100 electrons but there is a tip of your pen where there are 10 so you can easily visualize that the density of electron at the tip of your pen are way higher is way higher than the density of the electrons in the room so your tip of pen has higher potential than that of the room so charge will flow from the tip of your pen clear mean 2 2 2 2 2 the loop now what Andhraag is saying okay voltage the work done to move a single coulomb of charge understand this it is not the voltage it is potential and that is in the terms of electrostatics in 10th grade you are telling the answer which I explained you in the class in 10th grade you don't have electrostatics okay in 10th grade you have electrodynamics so Andhraag what I was stating is key yes that is potential voltage is not potential voltage is potential difference remember this let's proceed so this is the most important part because while walking through the previous year papers circuit diagram was something which I like kind of in every paper experience okay for knowing the circuit diagram what you should know is the logic symbols few you remember like you remember how a resistor looks like you remember how a cell looks like you remember how a battery looks like literally in some papers there was draw a circuit having three batteries of four volt each so what it mean it mean that you have to draw one battery like of one cell two cell and three cell of four volt each so you can write 12 volts you're getting my point so this is the way the CPC has really designed the questions in many previous year papers I'm not making up it like a random question it is a genuine question okay yes should this voltage will add up that's why if you will see in our cell like in our devices when we connect cell okay they are connected in series this kind of polarity negative positive is called additive polarity if I will have two volt battery connected with a one volt battery then the total out of this is this type one volt this is called additive polarity and subtractive polarity this type 4 4 4 is an additive polarity resulting to a 12 volt output whereas 2 volt and 1 volt connected with a subtractive polarity negative to negative or positive to positive will result to 1 volt clear or not so this is subtractive polarity here this subtractive polarity similar type of terminals connected yeah so either this way or this way it is a subtractive polarity okay what are is application here so additive polarity is the application subtractive polarity with like kind of why will if I can design a cell of one volt then I'll use it right just telling you keep by mistake if you connect like this you will be having a subtractive polarity so we we as humans I don't remember any device where subtractive polarity is used it is kept to be there okay so fine and as Pushar bhai is saying key if yes for raw application where there are limitations like you have a 5 volt battery and a 4 volt battery and you only need one volt output then you will use a practicality yeah so fine so back to the rhythm other logic symbols are the rheosted very important okay this is the rheosted also denoted by capital R into H clear so this is battery this is cell this is resistance as you ask about subtractive polarity similarly there is a question key so why we have variable resistance yeah sure so if we have we why will we have variation in like minor decimal rheosted can bring you variation for minor decimals and okay you don't have to sophisticatedly design a different resistance so rheosted is a primary see if someone is asking in the paper where they have asked this and literally there is a column match the column scene and we will be like witnessing it as well when we'll be solving previous a question so match the column scene okay here there are logic symbols and they here they are named you have to match them with the correct and all that so so yes this is an important portion clear then many people don't draw a ball properly bulb is like this okay so yeah fine so these are the correct symbols used by CBC for drawing the ball this is not don't just create a loop over there no this is not a answer they are not yes while practicing we like nobody regulates it but surely in CBC there is a marking on the logic symbol used in the circuit clear so this is bulb fine excluding bulb but please remember CBC doesn't discuss logic symbol of any other kind of load don't think that they'll be asking you sophisticated again please don't click on videos when you click on videos this is what comes on my screen it doesn't happen automatically one of us yes thank you very much one of us will enable the video and then this comes up thank you very much thank you very much so clear bulb okay yes what I was discussing is about other types of loads load is anything which utilizes power so I'm keeping one for the bulb for any other load if at all by some reason is mentioned in the paper please use a simple blank rectangle like terminal one rectangle this this will be utilized for any type of load L O A D load okay sure fine if at all in the circuit diagram they are mentioning to draw you like we had in our mock test right a question which many of you have made mistake whoever ever attempted the paper in class no problem I was checking the copies yesterday so I found it please don't draw fan and things make the box right load or if at all you want to be very specific right fan say for example Gokul what I am mentioning is it is asked in paper to draw our domestic circuit to draw a domestic circuit here with fan power supply and key so what will you do don't draw a fan like this okay so I am bad in drawing you guys can be great and can utilize your time in that so fine don't do that please make it like this this is standard notation fan actually you should write like load okay clear socket no no socket is never asked I have read it bitter so that's why I'm saying no logic symbol is utilized in CBSC and neither it is standardized by the CBSC in your book so please go buy the book in any case we will not be using random simple clear or not sure fine turn proceed so these are the standard yes dear can you just draw just draw some domestic circuit circuit with consisting of bull it is here if they ask us to draw a text book it's in NCRT they have given some kind of extra can get of saints and they have given 220 oles and stuff and they've got a few meter that is not in the chapter electricity it is in the chapter magnetic effects of electric current where they discuss about the safety instruments and devices so there they will ask you to draw fuse and everything and all okay it is in it is in magnetic effects of electric current and we discuss about safety devices are being and everything over there okay got it the next topic we have to discuss about is the very important one ohm's law what is the statement of ohm's law mathematically it is V is equals to higher and in words it is across a conductor the voltage applied is directly proportional to the current withdrawn or the current withdrawn is directly proportional to the voltage supplied clear not sure this is the statement of ohm's law V is equals to IR in order to remove the proportionality and bring up the equality we use the constant okay so the ratio of the and work of current and voltage remains the same V by I is given as our resistance see resistance is a separate topic you don't have to comprehend resistance in ohm's law okay so so V is equals to IR prominent formula and yes you guys are going to use it in the like highly probable numerical which is going to be a part of your examination paper okay V is equals to IR what I think or estimate is the formula from where you are going to get the question numerical question from this chapter clear so what you should remember is that yes when resistances are corrected in series the current remains same okay whereas when they are corrected in parallel the voltage remains same clear so this is the agenda which is going to be utilized by the numerical so yes parallely they will also be you asking you the equivalent resistance of the combination yes for that we have another card to discuss clear V is equals to IR then there is one more type of question which is observed yes what is the characteristic curve please mute yourself dear whoever you are I don't want to scroll and find your name and or I can use this now so clear and the answer is you guys know a straight line clear yes there is a definition which is also mentioned in few previous year paper quite old not very recent what are non-omic conductors conductors which do not follow ohm's law are called as non-omic conductors if it is a two marker kosher if it is just a one marker okay you can state an example examples are semiconductor semiconductors do conduct but don't follow ohm's law okay so should you ask about examples okay so the curve for non-omic conductor is a curve okay it's not a straight line the VI diagram is a curve okay charon akash mercury very good okay clear fine so that is about ohm's law then we proceed to the factors on which the resistance of a conductor depends so here we discuss about resistance comprehensively the resistance by mathematical formula is given as r is equals to row L by a clear where row is resistivity resistivity the property by virtue of which noted down the property by virtue of which a material shows resistance is called resistivity resistivity is the property by virtue of which I am talking about kind of bookish term but they are required by virtue sir when you repeat the statement again I am writing it on screen with a by virtue of which a material shows resistance clear sure so on what all factor resistance of a material depends or resistance of a device depends it depends on three things resistivity length and area prominently you can also say it in two ways it depends on the quality of the material and the dimensions of the material dimension as a single word will include both length and area okay sure with increase in length as you can see resistance is directly proportional to length so with increase in length resistance will increase with increase in area resistance will decrease clear with any change in dimension the resistivity will not vary resistivity will only vary if the material is changed or temperature of the material is increased or decreased to a high extent just not by minor changes to a high extent okay sure so resistance of a material depends on the quality of the material or the material itself plus the dimensions of the material clear sure now based on this yes there are going to be questions like of please remember yes dear is silicon a non-homic conductor silicon is a semiconductor hence a non-homic conductor oh thank you sir good now variation of resistance there are questions to be on two models cutting a wire and stretching or compressing it when you cut you only vary length area remains as it is okay sure when you stretch or compress both length and area will vary clear sure when we talk about cutting if a wire is cut to nth part r new will be equal to r old by n clear and quickly passing through this because this is what we have always discussed in the class and proof and all have been done so just writing the points to be pondered by you okay sure clear stretch or compressed in any way okay to nth part you know then r new will be equal to n square times r old i am talking in terms of stretched so when you compress you will be making it half so it will be one by four times the r pretty obvious clear sure we have sample questions attached over here so it will be easy for you clear sure this is about the factors on which the resistance of a conductor depends clear easy can we proceed sir i have a doubt yes dear sir if length is doubled then what will be the new resistivity great in order to double the length you will not just like add another length right or not you will stretch it clear mm-hmm so l old l new yes or no l new is two times l old that is what you are saying right or not yes sir r new will be four times r old yes sir but what is the new resistivity will the resistivity change will not change resistivity i stated the term resistivity will not change with the changes in dimensions okay okay so any change through the dimension will not bring change into resistivity resistivity will only change because of change in material you change the whole material itself or for the same material you change the temperature to a high extent okay either increase or decrease clear or not yes sir thank you okay no problem now the resistance of a system of racer so yes you have two types of systems of racer series connection and parallel connection right or not in series r equivalent will be equal to r1 plus r2 plus r3 and if there are n registers then till rn the sum clear or not so r equivalent in parallel combination will be equal to 1 upon r1 plus 1 upon r2 plus 1 upon r3 if at all there are many then 1 upon rn clear or not i knowingly write it like this because what you guys generally do is okay if 6 and 3 are given then you do okay 1 upon 6 plus 1 upon 3 which is 6 yes or no 3 1 by 2 just leave it over there don't do that this is there please remember it clear sure please remember our equivalent is the reciprocal of the whole thing clear 1 upon r1 plus 1 upon r2 up to because many a times when we've conducted monthly test over there in the family we have experienced this that many especially like at exam though you are a bit more cautious yes but the problem like when we are practicing many a times you guys make this mistake left it at 1 by 2 no the final answer is the whole reciprocal so two ohms will be the final answer yes or no the unit of resistance is ohms logically represented by this like sorry sure or ohm clear sure fine great now heating effect yes dear so somebody wanted you to do the complex circuit yes sir rf wanted you to complex circuits okay chalo we'll do a complex circuit but there are like very easy complex circuits as far as the 10th grade of cpsc is concerned okay i did not want it to deviate myself but yes one question is no bad okay so suppose rf dear there is a circuit here chalo fastest fingers first okay clear what is the equivalent resistance of this combination good good good good good charvi the first correct answer goes to you because you have stated with units not the shitage you miss the unit i'll deduct half marks or one if i am in a bad mood okay someone in between the spawned at 20 i could see it who is this dear charanakash friend of mine re-correct your answer okay no problem but this kind of mistake will lose you good opportunity to score centum in your respective exam this whole effort is to make you you're anyway getting more than 90 be happy with that the whole effort is to bring you on centum not as close as to centum on centum okay sure yes the other typing skill learning can happen later rf chalo back to the scene i hope this is clear for those who couldn't answer i'm just explaining it quickly these two are in series will respond as two these three are in parallel so one upon two plus one upon three plus one upon six whole to the power minus one which will answer as so no six being the ncm three plus two plus one to the power minus one so one five four and this one are in series which equates to ten okay dear sure chalo fine proceeding further the heating effects of electric current okay clear sure for that i guess it is better to consider electric power first and then heating effects because the heating effect of heat which is energy right or not electric circuit will come as power multiplied by time power especially for the case of heat is i square r okay clear now when i'm discussing it here i can also mention the other variants of the formula for power power dominantly for like primarily not dominantly for electric circuit is v into i voltage into current so energy in an electric circuit will be equal to v into i into t power multiplied by time we have multiple formats by the help of ohm's law for power like v square by r or i square into r when we talk about heat yes this is what is considered as the heat released clear sure fine cool so this is what is the like overview of the whole chapter i had a plan that i'll just discuss this for a maximum of 30 to 40 minutes but yes kind of an r fully is utilized in this discussion now we'll be taking a tip into the i don't know questions clear grab your pen and paper because you will not be having a liberty to calculate on screen please don't do that even if you can um so we all the questions are fastest fingers first okay excluding the theory part numericals only clear sure sure so also remember all these questions have been pulled out from the previous year yeah ohm will be okay no symbols for the units okay so ohm is what is standard format of writing the unit of resistance other units of uh like other terms which are involved will have alphabetical units or symbolic representations clear sure no units will be there make it a habit from product on world please write everything specifically with the unit never make a mistake for your own good because i wanted to like make it a habit for my dear ones i have also taken like for the centymar to be conducted for ninth grade i have made it a regulation that i'll only be writing everything with a unit around it okay or specifying the unit of whatever i'm writing so back to the scene dear let's start these questions are taken from okay previous year papers clear so they will have their standard answers and all clear sure there are new format of questions which are being introduced by the cbsc there will be multiple choice questions plus fill in the blanks answer so the first question electric potential is a scalar vector neither a scalar nor a vector or something scalar and sometimes vector a a a a a is the answer so this is the perfect way of answering a bracket scalar is the correct answer yes so note down electric potential is a scalar now this question being published by cbsc gives me a very direct hint that i should not leave it over here only let's get introduced with all the uh parameters used in the electric electricity as a chapter nothing in this chapter is a vector nothing in this chapter is a vector everything is a scalar please make it a note everything around electricity as a chapter is a scalar got it no no no no no no no no under eye dick don't get confused suppose there is a wire like this so the current will go this way and this way here are these two currents different no they are same got it so current is a scalar let's talk about this in 12th grade chapter one okay not in 10th grade clear so got it anything in the chapter electricity show clear will be scalar only no vector next when electric current is passed electron move from when electric current is passed now this is a tricky one when electric current is passed okay few D's few a one C as well in the direction of the current that is the absolutely wrong okay now one person who has stated a please write your response one who has stated D please write your response I'll name Madhumita write your response or reason for D shit is write your response for a Gurman now why what blinked in your mind so that so you stated key by okay D has to be the answer Rasha I mentioned it in class electrons move from negative to positive no understand this in the beginning of the chapter in the beginning of the chapter right we had a discussion clear that voltage movement of charge from higher potential to lower potential okay so yeah so what is the intuition of what is the charge over there positive charge or negative charge again I'm repeating I stated our sentence potential difference right and movement of charge when we were discussing about current so charges have a tendency to flow from higher potential to lower potential good what type of charge I was discussing about positive charge or negative charge negative no understand this come back to the grounds this is your battery this is the negative potential and and this is the positive electrons are moving right or not clear and the only correct answer for this is B why I'll tell you the reason remember this when see this can also be the answer but here a word conventional is missing conventional current is opposite to the direction of flow of electrons actually electrons flow from the negative terminal to the positive terminal okay sure clear this is the answer now talking about the next question no further discussion here no further discussion means no miscellaneous discussion not further clear this question an electric bulb is connected to 220 volts generator fastest fingers first be 110 watt okay power has its unit as what I missed it why I was explaining you this thing power has its unit as what okay wattage so be be be be be be be what is 10 watt is not at all than option shares channel quick calculation equals to be into I so power is equals to 220 multiplied by current which is 0.5 which is also half 110 water yeah sure no one will get sure I guess try 0.5 by 220 you might clear channel back to this pace what is the commercial unit of electrical energy sir yes dear sir just a minute for the question itself then I and Shruti before I'd asked whether electric field was a vector or not electric field intensity is a vector but it is not associated with electricity understand at the beginning also I stated in the 10th grade slivers there is no mention of electrostatics electric field is a static feature of electricity here okay to clarify your doubt yes exactly electric field intensity is a vector okay so answer what is the commercial unit of electrical energy I guess many of you have given it yes kilowatt hour sure in NTSC and here also I expect one joule is equal to how many kilowatt hours fast calculation one joule is is equal to how many kilowatt hours good man I remembered that you remember it that's why I asked this question good for those who don't know how this got converted so please remember see kilowatt to joule okay so see kilo is 10 to the power 3 what is joule multiplied by okay joule per second one joule per second is what is the definition of what WAWT and R is 3600 second joule is also here okay this is 3.6 into 10 to the power 3 and 10 to the power 3 is 10 to the power 6 okay fine sure sir you asked one joule is how many one kilowatt hour sorry how many joules sorry sorry sorry sorry sorry sorry big mistake one kilowatt hour is how many joules great thank you next electrical resistivity of any given metallic wire depends upon straight question obviously the three things are dimensional clear great next don't worry I'll be following up the fastest finger first post the lecture okay as of now time doesn't allow us to do all that fill in the blanks type the SI unit of current is ampere with capital A is the correct answer according to law the potential difference across the end of a racer is directly proportional to the through it provided it remains constant okay so this this block will have ohm's law okay the potential difference the current through it clear what show if required as ohm's law and here yeah next the distance of a conductor depends directly on its length inversely on its area and also on the resistivity of the conduct okay good the as see guys don't get panic if someone deducts your mark on wrong arrangement of the sequence directly on resistivity inversely on its area and also on the length of the conductor is a wrong answer directly on its length inversely on its area and also on the resistivity of the so the SI unit of resistivity is please note it down SI unit of resistivity is ohm meter ohm meter okay so at last if the potential difference across the ends of a conductor is doubled okay the current flowing through it gets doubled for obvious reasons me and I are directly proportional to each other based on ohm's law yeah not halfed someone stated halfed yeah yeah fine great now theoretical and numerical types of question what is meant by electric current the passage of charge per unit time the flow of charge per unit time through a conductor is called electrical clear what is this SI unit is SI unit is ampere definition when one coulomb of charge passes through a conductor in one second time then we call one ampere of current passing by anyone looking for a written answer for anything I am stating feel free to state I'll write it down no problem I repeat some other kind of conversation is going on here some people are answering the things great great great great great great great sure clear so I repeat can we have defined what is electric current done the name of the unit is ampere and the definition is one one coulomb of charge passes through a conductor in one second we call it one ampere of current clear in a conductor electrons are flowing from B to A okay what is the direction of conventional current A to B right or not and they are anand the bourbon bad worst joke of my life give justification for your answer so the same thing current is the passage of charge okay so conventional current is considered to be flowing from higher potential to lower potential which is the opposite direction of that clear as a should I write I'm writing back okay so if you are looking for justification right so see lower potential you can complete these words okay sure which is exactly opposite to the flow of charge electrons clear this word itself this is very very important conventional the last part of this question so this is a big five marker okay yeah so this is a big five marker I did not wanted to spend my time now the last part a steady current of one ampere flows through a conductor congratulations calculate the number of electrons beautiful says 6.25 something you guys were answering great calculate the number of electrons that flow through any section of the conductor in one second so yes or no n into e is equal to I into t so n is equals to 1 upon 1.6 into 10 to the power minus 19 I am not writing any unit here because it is a number clear sure so clear or not 100 by 16 into 10 to the power positive 18 19 or 20 yeah guys job proceeding further some extract activities are going on in the chat just not make them distract the class okay what is meant by electrical resistivity of a material so you had the definition stated by coming on screen like someone else stated I reflected on the screen it is resistivity is the property by virtue of which a material shows resistance clear derive its SI unit so you will derive R which is ohm is equal to resistivity into meter upon meter square so resistivity will have its unit as ohm meter yeah yeah job next part of the question describe an experiment to study the factor on which the resistance of a conducting wire depends yes now this is the describing part clear now you know primarily are by the formula is dependent on row and a so you will have to write three steps one to test the variation by length one to test the way the variation by area and one to test the variation by temperature clear so please don't get confused here they are talking about resistivity and here they are talking about resistance so if they would have been talking only about resistivity then you will be only measuring the effect of temperature you will not be measuring the influence of L and a right so when they are talking about resistance yes we'll have to mention the impacts of both the length that is the dimensions and the temperature length and area and now how will you single liner answers how will you examine the length the variation by length single liners what activity single liners good longer wire and shorter wire area cutting the wire is also a good thing dear charan good answer area stretching or compression the wire or using two different specimens of seam wire okay one thick one and one thinner one good and temperature by heat clear or not sure also sorry also when you are mentioning the temperature please mention significant variation in temperature please mention significant variation in temperature okay great right two points of difference between electrical energy and electric power two points very quick I would be interested to get the mathematical formulae question is good good man good good good good so the first line will have two points of difference their mathematical power I square R T and I square R this is power and this is energy unit unit of energy is kilo watt are whereas unit of power is just water clear so out of 60 watt and 40 watt lamp which one has higher electrical resistance so resistance of a designed device is measured by V square by P so resistance is inversely proportional to the power so the one having lower power will have a higher resistance what is the commercial unit of electrical energy given over here converted into joule already practiced clear so see year by year they are asking you what I'll be doing is I'll be sharing with you guys answer booklets okay the shop I generally like he makes it an integral part of his presentation only red not clear as I had too many things to do so I have kept it like this sure easy fine what will I be doing is I'll be sharing you the standard five years answer booklets okay fine great next question define one volt see this is the mathematical thing they are asking define one volt express it in terms of SI unit of work and charge calculate the amount of energy consumed in carrying a charge of one coulomb through a battery of three volts this is absolutely important sure so Gurmann very precisely as stated that voltage is yeah sure very well defined by stress okay express it in it's like terms of SI unit of work and charge so voltage is joule per coulomb okay so now calculate the amount of energy consumed in carrying a charge of one coulomb through a voltage of three volts three joules yes or no clear but the same line Q in two ways the work sure this absolutely correct it's the definition of electricity electrostatic definition of voltage proceeding further requires a and b are of equal length okay and have equal resistance clear very clear they are of equal length and equal resistance if resistivity of a is more than b oh oh resistivity of a is more than resistivity of b which wire is thicker so R is the same L is the same a1 and a2 row 1 and a row 2 see this part has to be equal to this part right or not row 1 upon even has to be equal to 2 upon then it implies that a1 is greater than a2 am I correct clear this is the way you have to like not this random way I'll write it step by step as well even r1 is equals to R2 you can write row 1 L1 upon a1 is equals to L1 and L1 got cancelled so R1 upon a1 R2 upon a2 simplifies that a1 upon a2 is equal to R1 upon that a1 is clear so mathematical responses will be validated more in boards please remember this writing 10 lines and 3 4 like see you will have to explain then write this okay the same what you understood when I was speaking is the same thing what examiners understand by words they don't have time clear and CBSE has given very straight guidances and instructions that that that give more preference and award to a figurative and mathematical representation than a theoretical representation please remember that okay so sure moving on to the next question I guess this is done yes the right relation between heat energy produced in a conductor when a potential difference V is applied across its terminal and a current I flows through it for time T very straight heat energy in that case will be given as V high T that's very good so yeah you can yes actually I am not very correct as you guys are you should heat use it as heat is equals to be it instead of using energy very straight answer right or not clear next question oh something diagram and all the figure below shows three cylindrical copper conductors okay along with their face okay area and okay so sure face area and then discuss in which geometrical shape the resistance will be highest so you will be writing it as you will be writing it as R1 is equal to all our copper so resistivity will remain same length is L upon area R2 is resistivity same length is 2L upon area is a by 2 so making it as 2 into 2 so for the row L by a okay this L is a small one this is capital so matching the same notations okay third one R this is R2 R3 is equals to row same L as L by 2 into 2 a so it will be 1 by 4 row L by a so R3 is the least then R1 and then comes R2 whatever they may ask right in ascending descending greatest lowest this is the answer clear or not clear easy this representation is the best help instead of writing too many sentences on all mathematical representations will be preferred okay shares thank you now for some circuit final I'm like eagerly waiting from for circuits from long where all circuit and then comes this simple question I hate this find the current flowing through the for it is an exam question actually so now while hand picking these questions the preference was given to different types of questions okay from all topics there should be questions so find the current flowing through the following electric circuit when I was mentioning these things I also witnessed few questions where instead of mentioning this they they have asked about amateurs and volt meters clear amateurs is the device used to measure electric current measure whereas volt meter is a device which is used to measure electric voltage volt meters are always connected in parallel with the resistance across which the voltage has to be measured whereas amateurs are always connected in series across the circuit or the resistance through which current has to be measured the resistance of amateurs is kept as low as possible the resistance of voltage is kept as high as okay so back to the scene find the current flowing through the following circuit so for any circuit diagram the first thing whether as or not you have to find is always are equivalent our equivalent over here is 3.6 in series ohm is in series with a combination okay and then again with series with 3 ohm this combination is off parallel system yes or no so this is your total answer clear fast what is this 12 here 2 plus 3 5 to the power of minus 1 plus 3 3.6 plus what is this 2.4 plus 3 so the answer is 9 ohm clear so now second step goes to calculation of current current is equals to V by R are equivalent V is 4.5 upon R equivalent is 9 so 0.5 ampere current is the answer okay what is this 2.4 shares that's a 2.4 might be this yeah yeah okay got it got it no problem yeah easy now I am just like increasing the level of the question if it is a 5 marker they can also ask what is the voltage utilized by fastest fingers first what is the voltage utilized by and a chocolate question as when what is the voltage utilized by 3 ohm resistor this is the 3 ohm resistor I am talking about so in order to reduce your confusion what is the voltage utilized by 1 ohm resistor not the 3 ohm resistor there is only one 1 ohm resistor what is the voltage 1.5 Charanakash 1.5 okay why they 1.5 volt okay why why why why why so should answer for the 1 ohm and my question now is for the 1 ohm resistor 0.5 volt I'll repeat the instruction please mention it by units with units 0.5 volts okay for those who have done let's verify the question for those who have not done yeah I'm explaining how this is done yeah for that what I am doing is I'm just creating a rough box for me over here is my rough box see understand the current being drawn from the battery is 0.5 ampere or half okay there are many ways of answering clear sure out of which the simplest way to carry this out is okay if this is the case then the voltage utilized okay by series resistors is 6.6 into half that is 3.3 volts I into R I into R so the voltage remaining for the parallel box is 4.5 minus 3.3 which is 1.2 clear 1 ohm sir this is here can I just explain how you did it because I did it randomly I still got the right answer I don't know how great I'm explaining how how I did it what how I did what 3.3 once again yeah I'm proceeding I'm proceeding so what I have I done is one way I'm following up the voltage which is already utilized by others is 6.6 R into I half so 3.3 volts is already utilized so remaining is 1.2 which will be utilized by the parallel Dubba parallel Dubba comprises of two things this is 6 and this is 1 and so the current in the 6 wala yes or no clear sure I is equals to V by R 1.2 by 6 0.2 okay so the current here current upper branch will be equal to 0.3 why because the total current coming at this junction is 0.5 0.2 goes here so what will be coming down is 0.3 clear so the voltage of one ohm will be equal to I into R which is 0.3 ohm anyone who got 0.3 you know one I guess because I could read 0.5 and all shit it 0.3 ohm wrong 0.3 volt thank you for reminding me okay is it clear a quick why or end quick answer what is the power consumed by 6 ohm resistor what is the power consumed by 6 ohm resistor quick what is the power consumed by 6 ohm resistor I hope dear the actual question which is on the board this much only is for three or four marks three marks okay but what I am trying to create now is suppose they want to state a fine marker then they will be shortly asking all these things okay what is the power consumed by 6 ohm resistor 2.4 watt others so see power is given by multiple formats V into I V square by R or I square by R which format you want to follow sir it's I square R not I square by R where where what are you talking about dear that's what you know I couldn't get what no no no it's fine no I before you wrote I square by R no false claims no no no I square R is what I have written only I square by R scan who charnak asharankur chala chala chala back to the same okay okay fine so yes power about the power power consumed by for example 6 ohm so power is V into I I have I in the 6 ohm as 0.2 right or not and V as 1.2 multiplication 0.24 type power or I square by R I square in 2R sorry and all that yeah sure so things can go to more penetrating levels okay just next card calculate the resistance of a 1 kilometer long copper wire of radius 1 millimeter this is pure calculation do it I am not doing it pure calculation sir yes dear in the previous question some of us are getting 3.375 as the value of of the power I guess yeah the power V so by our calculation what we had is the current coming out of the battery is half ampere right or not so the voltage supplied to the circuit is 4.5 so what we had seen that the voltage across 6 ohm will be 1.2 volts yes or no sure now the current across 6 ohm will be 1.2 upon 6 so 0.2 ampere so the power will be voltage into current 0.24 watt now please tell me how was it going to be 3.375 let's calculate by other method I square in 2R okay so I think I took the voltage to be 4.5 volts that's all okay okay okay have I made it clear now for everyone a quick yes or no for this yeah yeah yeah I'll be scrolling down dear don't buy a quick yes or no please yeah very good now the next question here it is one kilometer one thingy calculate the resistance R has to be calculated resistivity has been provided 1.72 into 10 to the power minus 8 length is one kilometer so I'm writing it as 1000 meter upon 1 millimeter is the radius so see area has to be calculated area of the cross section will be pi R square oh damn you have to use 22 by 7 into R which is 10 to the power minus 3 square which becomes 10 to the power minus 6 yes or no beautiful calculation keep on keep going what no should it not do it I literally insist on you to do it for everyone solve it calculate this is the beauty of the exam I don't have the answer key of this so I'll have to trust on the majority so if majority will be answering one ohm is the answer then I'll okay say okay yes one ohm is the answer someone is going to the power of 10 to the power minus 2 few answers are 10 to the power minus 3 few have just straight 9.8 ohm why such a big variation there should be you did it calculator okay so what what have you like received as the answer okay the answer is so big that you don't want to type sure fine let's invest over some time over here 1.72 upon 3.14 okay into 10 to the power this is minus 5 goes up 10 to the power 6 and minus 5 is just 10 yeah so so it looks like 172 upon 314 into 10 which is now pretty decent because I can in the my rough space divide like this 4 3s are 12 5 3s are 15 5 approx I'll go 5 4s are 20 5 1 7 yes or no 15 and off so 0 5 1 decimal 0 so 5 3s are 15 so 10 to the power 5.4 so I'll write the answer as 5.4 ohm 5.47 good yeah sure don't leave it these kind of questions practicing them will just increase your patience level and that will be helping you out in the exam you can write but dear see better view like you should go even I cancelled it like at the second digit actually they're like as per CBC regulation what I remember from the expertise I have listened to they say key and stated otherwise minimum like minimum expansion which is expected out of a decimal is two places so 5.47 is more appropriate than writing just 5.5 two places of decimals are good okay chal proceeding on with the question draw a schematic or now finally coming to the case draw a schematic diagram of a circuit consisting of a battery of four cells of 2 watt volt each so cell 1 cell 2 cell 3 and cell 4 8 volt you can write okay connected to a key okay an ammeter okay there is a key there is an ammeter and two registers of 2 and 3 ohm in series and a voltmeter to measure potential difference across 3 so suppose this is 2 and this is 3 so it is here where the voltmeter will be connected and closing the circuit sure yeah sure channel proceeding further an electric bulb is rated 60 watt at 240 volt calculate its resistance okay very good resistance will be is equal to V square correct wrong will be equal to V square by P okay please proceed with the calculation don't miss the unit units are units please units the next calculate its resistance if the voltage drop to 192 volt okay calculate the power consumed and the current drawn by the bulb very good our consumed is V applied square by R you getting my point sure so put the value of R over here put the value of V as 192 over here you will get your answer current drawn PV into I assume see this is this is static resistance is same so you have to put the resistance as what is designed this is called the designed resistance resistors of the system okay clear so nice next question I guess there should not be any yes exactly 25 questions 25 slides were there 24 questions were there so odd 15 20 questions were there and is it fine I hope you are thorough with the chapter electricity if any doubt I'm giving you a window please ask them here a quick yes if there is any if there is no doubt remained please state a why I could read one no sir was the reference of that no sir was yes no doubts okay thank you now see the worst thing after this lecture is you are going to have an assignment that assignment will be shared to you I guess by tomorrow morning or to tonight only okay please follow that that will be having few good previous year questions few not too many but few good previous year questions which will be helping you out to thoroughly understand and clarify your queries regarding this topic and make you prepare for a sentiment this okay sure anything else can we close this up great bye sir stress has one doubt sir share share share please proceed he's asking how the resistance changes with temperature okay dear if I have to explain you the concept part of it shiteji would you like to explain that channel not then I so understand shares why why why is the primary thing that to understand why the resistance or resistivity changes okay this is your assembly ground you guys are standing in proper so someone has to pass through you can easily pass and try to not but suppose suppose this ground got heated up high so you guys will be doing random motions jumping here and there and in that case in order to pass through you guys will be difficult hence increasing the obstructions so when the temperature of a material is increased the interatomic configuration gets randomly arranged and vibrations started right particle start vibration vibrating in random order and hence another charge passes through it it experiences more by sir collisions by dear it experiences more collision as compared to its ground neutral state and hence the distance or better in terms of resistivity of a material increases with increase in temperature is it clear if current is increased by a hundred percent it means the value of current is doubled okay so for the same resistor the power utilized will become four times now you have to add up a clause keeping the voltage same and few more things changing the resistance and all that okay sure take care by sir anyway anyway I need increased percentage yes yes yes by by dear and you go out please feel free to ask bye sir thank you bye bye dear bye dear bye bye bye bye bye bye so yes dear can you explain why magnetism and electricity are so closely related no oh just kidding so actually what happens is see they are both very directly influenced by charge electrons okay yes sir and that is the primary reason that they are very like mutually existing they exist simultaneously it doesn't happen ever that only electricity is in the circuit every circuit having current is parallely assisted by magnetic influences okay that's simply because they both depend on property because the primary thing influencing or creating them is the electrons okay okay thank you sir okay dear bye bye bye bye