 okay hi good evening everyone there are only 15 people now so I would like to wait for a minute or so 16 now where are others why they are not joining how many people generally join so this one is this one really for the R&R patch they are not about a 25 vision I don't know okay people are joining let them join okay let's do one thing let's start with the quiz so if you look at the quiz for different questions different time time frame has been set up for few questions I have given three minutes also now there may be few students who will solve it fast but I'm least worried about them because what I feel is that each student should have enough opportunity to give the answer correct so I'm not looking at the time frame from the from the perspective of time frame today I'm looking from the accuracy perspective today so what happens now is that we will start solving the quiz of 21 people joining now and I think it's more than enough time to wait for anyone so let's start the quiz now can you all see this thing so you remove the fastest finger first no no I'm not removed it if you do it fast you'll get more marks but more than that why I have given more time because there there may be people who take a little bit more time to solve questions so even if they are suffering on the marks perspective from the point of view of time if they get it accurate that would be good for them so join the quiz please let me just stop this irritating show irritating sound I'm also posting the link in the chat box you can join from there they've been posted there are only three registrations till now six seven eight nine ten eleven twelve fifteen sixteen seventeen done okay I don't think people are going to join there are nineteen now I'm starting the quiz let's start this quiz first question is here this is 12 ohm this is 6 ohms this is 15 ohm this is 150 volt 150 12 this is not 120 this is 12 ohm this is 6 ohm this is 15 ohm I have only seven people who have answered this question and you still have 45 seconds which is more than enough time okay so time is up all 19 of you have given me the answer nine of you got it right and 10 of you got it wrong I don't understand the reason why this is happening if you have to find out how voltage so which connection is this can can anyone participate series in series in series connection what gets divided potential difference so current is common V is equal to IR so V would be proportional to R so V1 V2 V3 there there are three registers here would be in ratio R1 is to R2 is to R3 which is 12 is to 6 is to 15 which gives me 4 is to 2 is to 5 and V1 plus V2 plus V3 total would be equal to this voltage difference 150 so 4k plus 2k plus 5k is equal to 150 so 11k is equal to 150 or K is equal to 150 by 11 so 2k would be equal to 300 by 111 15 to 2 that was 2 times 8 0 it was 7 times then 3 2 to 27 point this is one way to solve the question the second way to solve the question is find out the current through this so 150 divided by total car register resistances 12 plus 6 plus 15 how much it comes 12 plus 6 plus 53 so current through the circuit is 150 divided by 33 and I have how much resistance here 6 so V is equal to IR so potential difference across this would be current 150 by 33 into 6 so how much this is this is to this is 11 so again 300 by 11 300 by 11 is equal to 27 point 24 any method you can apply is it okay this one is a smaller enough time I have given for this question I've got 13 answers till now okay the time is up I got 20 answers 15 of you got it right very good the answer here is if a current comes from here please understand how we have to find out if a current comes from here and we apply a I mean and connect a battery here so current I comes here it has three choices I1 here I2 here and I3 in this so the current Ivan will pass through this I2 here and I3 and so this 3 and 2 are in series because same current I1 is passing so 3 plus 2 5 so between a and b in the upper circuit 3 plus 2 becomes how much 5 ohms why because this is 30 ohms I don't need to worry there are only there is only one resistor and here 6 and 4 are in this is 30 ohm this 10 ohm and this is a and this is b so the all three registers are between two points a and b it means that they are in parallel so 1 by r a b would be equal to 1 by 5 plus 1 by 30 plus 1 by 10 and this is 30 so this makes me 6 plus 1 plus 3 which is 10 by 30 which is 1 by 3 so r a b is equal to 3 ohms is it okay did you understand this so good we have solved two questions the third question is on the screen now but I'm happy 10 of you got it right in this question I have given only one minute because the question is easy the wire the wire is a resistance free time is up only 16 could answer this question but please let me check how many of you got it right so only five could get it right please understand here that this is known I have taught this in the class this is known as shunting shunting means making potential difference zero across any electrical equipment write down again this concept any electric okay so how does it happen so you have a register here and once you join a line sorry once you join a wire across it this wire is considered to your very less resistance so most of the current will go through here through the least resistance and it is not pass here so the potential difference across this 60 ohm would be equal to how much zero do you understand so this this process of connecting a wire across an electrical equipment is known as what shunting how many of you understood it yes okay why so many such less number of people have answered this only seven people calculate the current across 20 ohm registers you tell me what is the voltage across 20 ohm registers what is the voltage across these two points these registers are in which combination tell me anyone otherwise I'll take names these are parallel combination so in parallel combination what remains common across all the registers or all the potential difference so what is the potential difference here 200 volts so if potential difference is 200 volt will it be common across all the registers yes yes right V is equal to IR or I is equal to V by R which is 200 divided by how much 20 20 which gives you how much what is the answer what was so big in it don yes okay still 42 seconds left out and eight people have not answered okay I have the leaderboard in front of me and Samai is leading now along virtual 12 of you got it right which is again a good result total current for total current I need to find out total resistance so 1 plus 2 is how much 3 so this 3 ohms would be in parallel with these three ohms so 3 plus 3 will become 1.5 yes or no because 3 ohms in parallel would be 3 into 3 divided by 3 plus 3 so 9 by 6 is 1.5 so it means that this total combination from here to here is 1.5 register is 1.5 add these particular things so 5 plus 4 9 9 plus 1 is 10 10 and a half so 120 divided by 10 and a half see how I eliminate answers 120 divided by 10 would be equal to 12 so anything greater than 10 the answer would be less than 12 less than 12 there is only one answer 11.4 2 and yes hence the answer is 11.4 so but once you get the 1.5 that you can you know can't be a whole number right so you just find the only decimal option okay are these two are these two registers in parallel 12 ohm and x ohm yes sir so along this x ohm register along this x ohm registers what is the voltage the voltage would be 135 volts yes or no tell me yes sir yes V is equal to IR I has been given as 5 ohms so 135 is equal to 5 into x or x is equal to 135 by 5 which gives me how much 27 27 answer is what 27 done okay 8 of you got it wrong why when a current comes here is the same question it goes here it goes here 3 plus 2 is 5 and this particular let's say this point is P and this point is Q so between P and Q there are two branches one branch is of 3 plus 2 5 so this becomes between P plus Q this becomes 5 ohms and this again becomes 5 so 5 5 into 5 divided by 5 plus 5 is equal to 25 by 10 which is 2.5 ohms this is 2.5 ohms and this is 1.5 ohms which is equal to 4 ohms is it okay because this is the current which will come from the circuit will pass through this 2.5 plus of 1.5 is 4 and when 4 and 4 are in parallel because between this P and B this is the one circuit and this total is between P and B 4 into 4 divided by 4 plus 4 16 by it which is P 2 answer is 2 solve the next question okay very good I have 11 only 16 answers but 11 of you are correct very simple when it when a current comes here it has two ways to go this way if I1 goes here this I1 will go through this go through this and come here is it okay and if I2 goes here this will go through this and this will come here it means that this 10 and 20 are in series so 10 plus 20 is equal to 30 ohms and this 5 plus 15 is equal to how much 20 ohms and these two this 20 and this 30 they are in parallel because they are they are between two same points so 30 into 20 R1 R2 divided by R1 plus R2 is equal to 600 divided by 15 is your sweet 12 ohms so answer is how much same kind of question given different way you are unable to solve very good 18 of you got it correct so total resistance in series you could you can take three of them so one two three because you add them up the total would be greater than all three of them because you are adding them it has to be series in parallel it will be lesser than the least is it okay I have discussed these things in the class okay let me check the parallel is correct here series is wrong yes sir that's what I was thinking but why is it series given in this when I have given the answer is parallel misclick can it be corrected now I don't know sir it's too late it is parallel is the answer I will get it changed so this is not finished up pretty early I could have given more number of questions okay ten of you got it right eleven of you got it wrong so look at here when it is saying that we understand when it is saying that same material same length same diameter it means that resistance it seems R is equal to row L by A and which comes out to be row L by pi R square this is same this is same this is same hence R is same of both the materials but the problem is one is connected in series to be then they are connected in series the total resistance would be equal to 2R so H would be equal to I square RT so now tell me so how much would be H I square into 2R into P this will be H1 and H2 when they are in parallel how much it will be R and R so that will become how much R by 2 I square R by 2 into T so how much should be the answer sir I will give first sir according to the resistance you should also calculate R in sir shouldn't we calculate R separately for different cases sir it won't be the same you should calculate R for different cases or I for different cases sir I have marked 4 is to 1 but it is telling I got it wrong yes it has to be 1 is to 4 yes sir because sir because the I will be different in each case you understand here you understand here let's say this is the battery so our resistance of 2R is here fine and this voltage is V so I would be equal to V by 2R okay so I will become V square by 4R square I square sorry so now H1 heat would be equal to I square which is V square by 4R square into resistance to R multiplied by T so how much this gives you this gives you 2 this gives you R so H1 is equal to V square T divided by 2R and when they are in parallel let me just remove this no one told except one person that I would be different and that's why 4 is to 1 and 1 is to 4 both answers have been given so when they are in parallel so that equivalent resistance is R by 2 if a battery of V is connected so I will be equal to V divided by R by 2 which is 2V by R that's 2 is equal to let's say this is I2 and this is I1 okay so I2 square into R by 2 into T how much this is I2 is 4V square divided by R square into R by 2 into T so how much it gives you this and this one this gives me H2 is equal to 2V square T divided by R now I have to find out H1 by H2 so H1 is equal to V square T divided by 2R and divide it is with 2V square T by R when you divide it to make it reciprocal it will convert into multiplication so this is V square T 2R multiplied by R divided by 2V square T V square T V square T 1 R R 1 it gives me 1 divided by 2 into T so 1 by 4 or it is equal to 1 is to 4 how many of you understood this understood sir understood sir understood okay all of you understood yes sir that is why this question was yesterday I told you that I will solve this question later so that is why I solve this question now fine so let me just have a look how many of you know the results and I will take attendance just wait sir for the 10th question which was sir will you like change the thing once you download it yes why but it did not affect your this thing okay am I sharing this screen this give me a moment what is to be done your attendance needs to be taken just wait a second Adya S is she there not there Adya M is there Abhiram present sir Achyut Achyut is there Aditya Aditya is not there Achyashree Achyashree was there she answered in the chat Anand Daksh Devank present sir Dhriti present sir Dhruv present sir Hari Keshav present sir Harsheet present sir Jatin Jatin Jatin is not there Maitreya present sir Maitreya Karthik Karthik is not there Namesh is here Namesh Ayangar yes sir present sir Mounid Sai is here Nishchal present sir Prajwal is here Pratap present sir Prajwal Pratap okay after that Pratap is here Riddhya present sir Riddhya Rishi Rishi is not there Samanjai present sir Samai present sir Shashvat Shriya Srinivasan Shriya Siddharth just wait a second Siddharth not there Sujai Sujai is not there Sujai Dharav is not there Tanmayi present sir Pijal present sir Yati Yati was there sure you can leave Thank you sir sir by student only R and R batch was attending this We have decided that because CBSE regular and CBSE autonomous are doing different things having same having same Centrum R was creating problems for the students okay sir it is it is it is because of that sure thank you thank you sir thank you sir