First of all congrats to all those who have been selected for the interview.Its indeed a great achievement as lot many appear in this prestigious exam .So we have abt 1-2 months left for the interview.So you guys can give suggestions on the interview like which subject to choose,questions related to that etc.I welcome suggestions from you all.From my school we have got 46 selections in which 32 are from SA and rest from sx.
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Spandan Senapati
1 year, 9 months ago
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Top NewestSo the kvpy interview is over.I am gonna share my experience.For me it was scheduled to be held at 9:00 am in NISER,Bhubaneswar. I reached there by 8:15.quite a far place.abt 22km from Bhubaneswar.It was adjacent to IIT,Bbsr.My interview started at 9:45 am after the completion of 2 students.The first one is a friend of mine(I don't know him much) who said after his that the interview board is quite friendly.that seemed a good gesture.So when I entered I just introduced my self,what I liked to do.etc.They asked what I had for breakfast and it was maggi for me.so they readily asked(chem) what chemical led to the controversy in maggi case.I didn't know.but anyways the person had himself told that this is not related to interview.so now of started.my topic was wave-particle duality,photoelectric effect and modern phy....somi was asked to explain photoelectric effect.on board which I did.then the physics prof asked me to split the work function into constituents.I did that it was binding energy+energy to remove that from the influence of all other interacting forces.then the mam asked on wave prop.then maths.I knew him as he is the director of institute of maths(where I had attended inmotcs in class 10,11)even he had felicitated me this yr for being 3rd in state in rmo.so he asked to prove that sum(j^99)j=1,2,3,4,5.was divisible by 5.I did that quite easily and could even generalise the case although it wasn't asked.the interview board seemed quite happy.I proceeded to factorise and proof the generalisation. And he didn't allow me to complete as he saw the first few steps and said "oh come on you can do after this quite easy" then something on relations.which I replied that I have not studied.and he said that it wasn't a big thing.I could do it anytime.then I was asked some conversions in organic although I didn't know them he didn't tell much and asked what I will do in future I said that I will do research (in mathematical aspect of physics) and they seemed quite impressed.and the next was a staple q(do you really want to join jee or do research)I genuinely replied research(as that's what I really wanna do).it came to an end and theybjust asked if I wanted anything to get clarified. I just asked what I can do to promote my interest as a student.The chem one replied that I was doing really well and I will do so.that made me feel quite ecstatic.and that was the end.later the director of niser(perhaps)wanted to meet my father.as he seemed to be quite happy with my perforomance.Later I went to canteen(some drinks)and returned.Believe me it was very big and great campus.and on way I even went to IIT bbsr.it is still under construction.nothing much but the field there is quite big.and it will look beautiful after some years.
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Any idea about what he told your father?
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No nothing much he asked me where is your father.I just introduced him.And he told something which I didn't hear awe stood a bit away from him...He seemed to be a good person.
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Can you please help me? A particle of mass 'm' moves under a force given by F= -kx^n.Find time period of oscillations if spring constant is k. Here n is any odd integer.
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Ya its of the form \(8x(o)^((1-n)/2)/w(n+1)int(sin@^\((2/n+1)d@)\)).with @ varying from \(0-π/2\) and \(w^2=2k/m(n+1)\) Here the numbers \(2/n+1)\)accompanying \(sin@\) is the power that sin has been rairaised to.and the no\(1-n/2\)accompanying the x(o)term is a power .
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Why will it not depend on amplitude?
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OK so it has a value of \((√π)/2T\((n+3)/2(n+1)\)/\(T(n+2)/(n+1)\)). T is the gamma function
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Comment deleted Mar 03, 2017
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Lot of messy stuffs involved..Just solving differentials.Not much n physics involved here I guess.
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Can you please explain how to derive time period from the beginning?
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Ya it will intact the amplitude is the x(o)term.Hey try putting \(.sin@=e^(iy)-e^(-iy)/2i.\)Most probably the binomially expanding yieldmsome thing but then that's not in closed form. No don't work it becomes tedious.
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What's m here?
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Yup closed form does exist use beta function and then gamma function done.
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So what did you get I don't know beta functions much.
r
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I have not solved it till end.You may directly use beta function's defination to evaluate that integral.Just look up on brilliant wikis.
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Well that's not in scope of JEE Atleast although i love gamma and beta functions.
@A E Can you share pdf?
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I don't have it now,but it was in some PDF related to MIT's open course ware.Try googling it,I suppose its still on their site.
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But many trignometric integrals as well as integrals of the form (x)^a(1-x)^b can be solved under 1 minutes (and it has appeared as a previous jee question where normal method was very long).
Thus it is worth learning even from jee point of view i guess.
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I learnt it coz i loved integrals when it was taught to us! and yeah that helped only in AITS :p
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Did you had any backlogs at the end of class 11?
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Yep many i had . one of my backlog is still there which i haven't overcame FLUID MECHANICS . In chemistry i mostly didn't got Organic of 11th which i improved in 12th . in maths combinatorics troubled me and it still sometimes coz its a kind of topic which you cant master completely .
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How did you solve it?
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How did you do it?I tried doing it with normal integration and things are getting very tedious?
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Ya substituted=x(o)(sin@)^(2/n+1).Although I don't know whether its closed form exists of the integral.But next let me Think
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Well this kind of problem has been asked in jee but was somewhat easier . If i can reckon correctly it had something proportionality constant (alpha)
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I found this question in some PDF related to SHM.
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Yup the problem mentioned smthing additional like small amplitude,i also remeber.
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Well i did SHM arhive in september 2015 but i marked that question coz i was not able to do that at first shot thats why i remember otherwise there are 100's of problems in archive
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Ha Ha it reminds me of my friend's interview last year . he was asked the time period for F = -kx^3 . IDK But the professor told him F = -Kx where K = kx^2
Hence time period = 2pi*sqrt(m/kx^2) i know its not logical at all but one of professors of the panel told my friend this :P :P
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Did they tell the actual answer ?
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Your interview went quite well plus aptitude marks = top 10 for you.
Congrats!
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No chance of top 10.I know a guy paean who is scoring as high in 90.and mine is 73.so its quite tough.but I expect a rank of within 100.BTW what's the highest in kvpy from yours state.I don't know sarthaks but his is mostly in 78-80.
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Yeah top 10 is really difficult . one of my friend got 86 in test and 64 in interview lasty year to get air 14
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Well according to your interview experience . you will easily get 80+ or even 90.
According to that if you equalise last year your rank will be in the range 25-50 (considering difficulty the same as last year).
I Got about 70 in test and 81 in interview ended with 59 .
My friend got 73 in test and 75 in interview ended with around 50.
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68-70 Nimay Gupta
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Ohk.
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Wish you all a prosperous holi! :)
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Happy holi to all 😀
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Same 2 u bro .....
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Yup same to you..........
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Best of luck @Harsh Shrivastava.for your interview tomorrow.do share your experience tomorrow.just stay calm and give your best.you gonna rock it☺☺
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Thnx!
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@Spandan Senapati @Harsh Shrivastava A question!
A parallel plate capacitor is completely filled with a dielectric sheet of thickness d and relative permittivity k is placed on a horizontal tabletop. The lower plate is glued with the tabletop and the dielectric slab is glued with the lower plate. The plates are square of edge length l and mass of the upper plate is m. The plates are given a charge +q and -q, then the upper plate is shifted horizontally by a small distance x along one of its edges and set free. Find the period of oscillation of this plate. Thickness d of the dielectric is much smaller than the edge length l.
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I have a nice question in physics. Will post it soon.Do try.
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And to the other question(on pressure) that you had posted I got \(V^2=\alpha b/(k^2-1)\).If the dielectric slab completely fills the space then studying the distribution of charges the net field at position ofa face of e dielectric is \(\sigma /2\epsilon (1+1/k)\).The charge on the face is \(\sigma (1-1/k)\)(on!y magnitude).Thus thethe pressure is \(b=\sigma^2 /2\epsilon (1-1/k^2)\)(for the limiting case).Again \(\sigma =CV/A=k\epsilon V/d\).Plugging in the prev exp gives \[b=V^2\epsilon /2d(k^2-1)\]Thus \(V^2=\alpha b/(k^2-1)\).....Although I think if not completely filled then the dependence will be on C specifically(and thus \(t,k\)
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I took the field to be sigma/k. But we must consider the field due to other charges excluding the charge layer itself
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Yes...I hope you got it
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It would be better with a diagram. But I don't see what thickness means here. Anyways we begin by noticing that when the plates of a capacitor are displaced then the capacitance of the system is given by \(A\epsilon/d.\)where \(A\) is the projected common area.So Here \(A=L(L-x)\) . Now \(C=kL(L-x) /d\). Force by the other charges on this plate is \( F=-dU/dx\). \(U=Q^2/2C\).Note that the charge remains the same but \(\sigma\) changes..Using this you get \(ma=-kQ^2d/2m\epsilon L^3.\) Now that we have acceleration as negative means it's gonna come back to its natural position, overshoot and head to an amplitude, return back. So \(t=4\sqrt (2x/a)\) The constant \(4\) for in one complete cycle it covers\( 4x\) distance.So this yields\[ t=8L/Q\sqrt (mk\epsilon Lx/d) \] .I used d as the distance between the plates. God knows how it's the thickness. Lol. Got It? And the thing wrong in the previous solution was the expression for capacitance...
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Nice one!!
This means we must not expect everything to be shm!!
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I am sorry. It's incorrect. Didn't notice that the dielectric has thickness much smaller than the edge length....
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Try this way let an external agent displace the upper plate by a distance X then \[W(agent) +W(capacitor) =0\] .Since for an isolated system in the absence of dissipation forces the energy remains conserved. Now since electric force is conservative \(W(capacitor) =-dU\) Where the second term represents the change in potential energy. Since no external potential is applied\( U=Q^2/2C\).Now when we displace the plates by \(x\) say then \( U=L^2\epsilon /\sqrt d^2+x^2\).Now put that in the equation \(F=dU/dx\). and terms of the order \(x^2\) can be neglected. This gives \(F=\psi x\). But we don't have any agent performing so the force applied by other charges on this is \(f=-F\). So the plate exhibits SHM.Find \(T=2\pi /\omega\)
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Us the answer.\(.T=2\pi L/Q(2m\epsilon kd) ^(0.5)\).I solved using energy conservation as there would be fringing fields here and directly calculation of the force may be difficult....
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In the answer there is a factor of 8. I don't know how they got it. T=(8l/q)(e0kmlx/d)0.5 and pi is not there!!
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Yes I know it's not gonna be a shy. It's gonna be a periodic motion with probably constant acceleration(I think) I will retry it.i didn't notice that the width of the dielectric is quite less. That's the error.
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Thanks let me try.
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@Spandan Senapati @Harsh Shrivastava @A E Sorry to Disturb
For us Differential Calculus got over.
Have you got any source for challenging problems??
I searched brilliant and mostly found integration problems!
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For us even function is not over!!!!
BTW I guess there is an acute shortage of diferrential calculus problems !
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For us definite integration is over.So I solve integration ones from Ronak aggarwals feed.Differential calculus I too want some good source.I think harsh can help us better.some questions from ronaks feed are quite tough.do try them.
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Sure. Lets see what harsh has got to say!
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@shubham dhull
bhai ye dekh
https://www.change.org/p/cbse-do-lenient-in-cbse-physics-exam-2017-for-class-xii
Itna mushkil to nhi tha paper?
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ghanta mushkil tha :P agar 5-6 number grace de di to mere to 100 paar jayenge number :P balki set-3 tha sabse mushkil maine saare set dekhe the haina bhai ? tere kitne aajenge btade bhai plz ?
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now i'm feeling bad about bragging too much without even knowing my real marks , just hope i get what i want btw math mein fatti padi hai bhai help @Prakhar Bindal
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@Spandan Senapati, @Harsh Shrivastava, @A E try this https://brilliant.org/problems/down-she-goes/
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I am getting a non integral answer, I used energy conservation and the fact that since string is inextensible,velocity along them would reduce to zero though I may be wrong.
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I also wrote momentum impulse equations.
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And I guess we are gonna receive the Kvpy results soon.Let's hope for the best.Lastyr it was declared on 22nd.March
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Why are you worrying? You will get through easily ☺
I am doubtful about mine.
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Arey don't worry .You will get through as well...You qualified NTSE stage 2 as well I guess
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I haven't tried it but is the bead fixed.Or the situation is just like a catenary.(chain hanging between 2 walls)
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@Spandan Senapati -- in that 65th question how to relate the rate of increase of temperature and speed of piston?? i tried something like PdV + VdP = nRdT. dV=Adx & dP=kdx/A since P=kx/A. and then divide both sides by dt. but then i am not getting that 3/8 in the answer.
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Hey there is a thing that the piston is nt massless so Weca t equate the forces perhaps.
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For 64 make use of the fact that the max theoretical increment in temperature accounts for the increase in internal energy =Increment in potential energy so \(nCv(T-To)=Mgh\) and \(nRTo=(p+∆p)V\).It's a valid supposition that initially the Tempnof the air inside is \(To\)
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@Spandan Senapati - Yah i got it now. First i considered even atmospheric pressure thats why i got some extra variables. Thanks.
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How was aiits? @Spandan Senapati @A E @Aniswar S K
I committed so many silly mistakes! :( Dont know when will i stop it :(
Srsly i dont know why i commit so many mistakes :(
My score=20+27+48(cmp)
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Ya.I checked the key it's so incorrect....Maths in a matrix I got-4(Hyperbola)The physics is wrong as well.Esp the first 2 questions.....(Now as per the incorrect key I got (33+25+57).Don't know but in maths the coefficient of(term independent of x is given wrong)...And they also gave that meso compound one wrong.Seriously I hate fiitjee exams for their incorrect answer keys.....
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Yeah m,any are wrong i dont know why but in every exam it occurs :\
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Oh yes you are right.I thought the ball was dropped when the other was at mean position.Rather its given that its the extreme........silly me.:)
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Lol many of these kinds of mistakes are committed by me also.We must stop making these mistakes!
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And the SHM was wrong as well energy will change as they stick...And time period and amplitude will change as well.......Careless people.Allen in this regard is grt.I have given n their xms twice and never was there a single wrong and.
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Allen isn't great in this regard :
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Why shud enrgy change?Also why shud even time period change?
See archive page number-65 jee advanced 2016 multi choice question 1 for a similar question.
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We have a screwed up schedule here.I told you.Here they conduct exams from 6-9pm and they don't put the answer keys even.How did you get the answer keys......I will be telling tomorrow.
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6-9 pm!!
Overall howasit?
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Maths was good.Chem seemed easy this time.Let's hope for best.Chill bro.I have exam tomorrow(chem practical)and I have bunked almost class(or absent).So I don't know even how do a simple salt analysis....(☺☺)And although I had done some in preparing for OCSc last yr I don't remember any.......
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Hey spandan, one doubt in the question posted by aniswar , I solved it by iaor method.But then I tried solving by force torque method that is by drawing individual fbds but could not solve it.My doubt is what forces will act on the particle from ground frame?
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Weight of the particle,contact forces by the rim..........But we need to analyse what sorts of acceleration it has.
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I was doing a calc mistake, got my mistake, and yeah result is same in both cases ☺
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Good....Were any answers wrong in phy and maths....Were did you get the keys from
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My center gave us key and some are wrong.I am posting solution to aniswars problem, do verify it.
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Ya it went nice.In Physics I think one and didn't match.That rolling one It must be \((8/35)v/ug\).
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I think answer is matching, coming out to be 3/7 v/ug many of my fnds also got 3.
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Well the friction will change its direction may be I did some calc mistake but its like this initially it acts backward so time taken for w to become zero=(v/2R)*(2/5MR^2)/fR.=v/5ug.and for v to become zero its v/ug.So w becomes zero first then v=4v/5at that instant.Next friction supports rotation and opposes translation so 4v/5-ft/M=5ft/2M(t=8/35)OK then we needed to add with the initial.so that t=3/7..Oh I missed that......Got it thanks.
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Comment deleted Mar 06, 2017
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Arey i tagged aniswar sk, dont know why you are tagged.
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@Harsh Shrivastava.can you share with me some questions that theyasked you in your interview.
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I was the last one to be interviewed so they asked me easy questions.
First they asked me C1+C2+C3+C4+....Cn prove this in two ways.
Then they asked a multinomial type question .
Then an easy physics question was asked.
Then some easy electrophilic addition question was asked.
That's all.Best of luck!
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@Aniket Sanghi @Prakhar Bindal
How is class 12th jee preparation is it more difficult than class 11th?
My class 11 is about to end.
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Nothing is difficult in this whole world ... stop thinking about that and let the studies keep going...
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I Would not say difficult (class 12) just its a bit bigger than class 11 in terms of syllabus . but class 12 mostly has 55-60% weightage in JEE So you can understand its importance.
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mine is 14.
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Hey looks like you qualified nsec.from your discussion.this is indeed a grt achievement considering the fact that you are in 11.which state and about your kvpy(when is it)
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Mine is 14/2 =7th rank
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in my school only 3 people have been selected 1 sa and 2 in sx
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Yup all the best @Harsh Shrivastava
I Will give just one advice. clearly say if you dont know an answer . dont blindly guess . stay calm, cool take your time to think upon the problem. you will rock it
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Thnx!
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Be confident , there main target is to check your confidence , they will try to just confuse you in your concepts itself and they will question you continuously , you just need to answer them with full confidence and correctness . And never answer those q which you don't know as wrong answers are not encouraged there and be upto the point , don't add extra waste things to your answer .
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will bio question would be asked to a pcm student
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I can't really gurantee that , but according to me they won't do such things . They understand the problem of students .
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Thanx for your suggestions.will they be asking questions from all the 4 subjects.
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Depends , for me , they ask my favourite subject (Physics ) and then they asked for maths also .
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What was your stage 1 marks?.does it any way matter in stage 2??
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My score was low due to Bio, it was 66.5 , however in second stage they dont ask your scores , they are not interested in that.
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my score in bio is just 11.total 72.75.did you chose any special topic of interest for it??and tell me how did you prepare?we have got mock interviews organised by our school.And they call scientists for that even.so even those who qualify the first stage by a small margin perform well in interview.any way I am also planning to go with phy.
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11 is big no in bio my score was 0.75😂
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Your score in 1st stage matters for selection , in second stage its obvious that u will get good score , I didnt do anything special for interview , just searched net for other people experiance.
My score in Bio was just around 6 :P
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Did u get answer key?? Could you post it ?? The paper was easy! What about the lnmodx question and hi cleavage question ??
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Sorry bro I don't have image.
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How was aiits ?
I am scoring 211-215 smithing :(
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HownHow much in P,C,M?
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Me scoring 222 as per this key.I guess the following answers are incorrect 1)Maths-f(x)=x^3/9.So x=+-3.2)Phy-Current through DE is zero right?Or am I fooling myself.And that matrix on potential energy x<x(2).that's incorrect.It can't be right?.
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how much is saarthak behera scoring??
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A new note has been created This is very bulky note now so let's communicate there.
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Yup some incorrect.
Also that HI cleavage matching is ambiguous. How do we decide major product? I thought ch3I shud be major.
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in that maths question its actually f(2x) = f'(x)f"(x) what option did u get for that maths match \(mod(ln(modx)\) - kx^2, only is k is negative, no solution??
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@Spandan Senapati What is your 4th subject?biology?
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Mine is Physical education.I had taken Biology in the initials of class-11 but I changed to physical edu.Taking PCMB is quite a strenuous job and when your target is IIT based there is no point in choosing biology.it just adds to pressure.
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I am appearing in KVPY 2017 SA. Is NCERT sufficient for chemistry?
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Ya its sufficient.Just read the organic of class-11 ncert properly.That will be sufficient.Chemistry section in Kvpy is usually easy.
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@Spandan Senapati @Harsh Shrivastava @Prakhar Bindal https://plus.google.com/u/0/photos/101887063519379114033/album/6435645121881596145?authkey=CP_iuKfL1cnN9AE
Try these and help me out!!
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And to the other problem on dielectric I will just add a general approach.We shall again make use of Ohms law \(J=\sigma E\).Initial charges can be found out easily \(C=A\epsilon k/(k+1)d\).Thus charge on plates of capacitor \(Q*=CV\) and that on plates of dielectric is \(Q*(1-1/k)\).Let's say we are asked the general equation of current at any time 't'.As usual let \(Q\) be charge on capacitor plates and \(q\) on dielectric(this won't be equal to \(Q(1-1/k)\) coz Resistance comes to play now.).So \((2Q+q)/A\epsilon d=V\).And from ohms law in dielectric \[J=-(dq/dt)/A.=\sigma (Q+q)/A\epsilon d\].From the first eq express \(Q\)in teams of \(q\) and set it in the second eq.You get time constant of the circuit as \(\tau =2\epsilon /\sigma =2\rho \epsilon \).Now you can get what's being asked.Although the eq of current was nt necessary its just formal.
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Thank you very much The mistake I did was that I took the charge to be \(q(1-1/k)\), and so I didn't understand what was going on.
Finally the electric field inside the dielectric is zero. So here do they behave like conductors?
The problem is we deal with ideal conductors and insulators in electrostatics and here conductors are resistors and resistors are insulators!!
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To start with the first problem.On Resistivity.It makes use of ohms law \(E=\rho j\).And so its evident that \(dV=\rho j.dl\).Here the second term is a dot product.Now choose 2 orthogonal set of directions.Here they are the directions in which \(\rho (min)\) and \(\rho (max)\) or (X axis)are oriented. Use Ohms law in this 2 directions.Its just a hint.Try this way you get something like \(\delta V=bV(\rho -\sigma )(sin2\theta )/2l(\rho (sin\theta )^2+\sigma (cos\theta )^2)\).Note that here \(\rho \) and \(\sigma \) stand for maximum and minimum resistivity
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i tried like this \(E(\cos \theta)\) = \((\rho)max jx\)
and \(E(\sin \theta)\) =\((\rho)min jy\)
then i found jnet in horizontal and jnet in vertical
i got J(vert)b / J(hori)l = \(b(\rho-\sigma)(sin2\theta)/2l(\rho(sin\theta)^2+\sigma(cos\theta)^2)\)
should i equate deltaV/V = J(vert)b / J(hori)l ?
how does the \(\rho)\) get cancelled? isnt it different for horizontal and vertical direction?
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Nice questions, from which book are they?
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Advanced problems in school physics
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Last question came in this year's open test!
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Hey how was aiits-1 for you.its just a week ahead.
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It was good for me . the only problem i faced was speed. the paper was hell lengthy at our time (312 marks total) and each part of the matrix was a new question itself. 4 Matrix per subject was too much . rest paper was quite easy. highest score was 296/312 whereas i got close to 275 in that
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My class 11 chemistry syllabus revision is left.I don't know why I am too exited for this aiits because this is the first ckaß 12 aiits and my 11th class aiits were disaster. :P
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Ya me too.I have to revise all three PCM of class 11th.
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How is JEE Preparation going on for you guys?
@Spandan Senapati @Harsh Shrivastava @Aniswar S K @A E
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Can't comment since no major test has occurd but better than class 11 :P
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Nice. I am still fascinated by the Olympiad world especially when spandan Senapati is posting about debaditya. Iam yet to go into complete jee mode!!
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Debaditya is a prodigy. Let me tell you abt another guy whim I met in Allen.That guy is in class 10 and topped NSEC and probably incho as well(his score is 87).He plans to break diptarka hait record of a triple ton in ICHO.
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Dhyey sankalp Gandhi??maybe future India's pride
BTW you go to Allen?
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No.Last year I had been selected for OCSC in IJSO.Generally there are a lot of practicals involved in the can p so I had gone to Alle kota for abt 15 days..Dhyey and I lived in the same hostel is a nice guy.I need to appreciate his focus.He took the entire of class 9,focused and completed the syllabi of chemistry olympiad
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Fine...I am more focused now.I really didn't take jee that seriously in class 11.
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Good for now. Finally I have learnt to manage my time well during exam and also I have developed an interest for chemistry .
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feeling awesome today guys
http://www.jagran.com/uttar-pradesh/lucknow-city-prakhar-bindal-top-in-b-tech-of-upsee2017-16108723.html
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Awesome!
Enjoy!
Btw our school topper is going mit this year.
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Keshav Gupta.he topped in nsep.how did he get selected.I mean debaditya pramanik is going MIT this year as well but he has abt 7+ medals in int.olympiadsolympiads(with 3 APHO+2 IJSO+1 IAO+1 IPHO inclass 11)..On which basis did he get selected.From fiitjee bbsr we had one who went MIT last to last yr coz he had 2 IMO medals.
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He told us that he was on some site named edex or smthing and was constantly contributing there.And his self appraisal was also awesome!
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congratzz bro ! .....
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Nice....and congrats a lot.....All the best.
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Got 96% in CBSE Boards class XII . I Dont know how and became second school topper :P
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Nice...Congrats a lot.I don't know how much our school topper has but anyway of our hper result isn't good then its a bad omen for us....We will have to study in hper period that's the worst thing.Just to make clear we have 6 periods a week and our teacher doesn't come abt 5 times.He is very busy.....so its usually a bunk period for us.
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@Spandan Senapati @Harsh Shrivastava Another one!!
https://brilliant.org/problems/tear-apart-the-dielectric/
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Ya I solved it.You get \(V=(kd+(1-k)t)√2b/(k^2-1)\).I have added the solution for a completely filled capacitor but when thickness is given just replace \(C=C(eq)\),and those 2 capacitors are in series.
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Thanks bro for problems! :D
Keep posting more! I'll also post some!
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Actually I dont know how to solve them!!I am missing some small point
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Could you tell how you solved it??
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Even I have also not solved them, I am studying capacitors now, and will try to solve them after studying them.
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Hey I tagged you somewhere asking for help in a chemistry question where I was stuck with Hoffmann bromide or halo form reaction following first. Kindly help.. Plz
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Sorry the notification is not coming. Could you pls give a link or tag again??
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https://brilliant.org/profile/aniket-5dxa59/sets/organ-blasts/434144/problem/be-careful-with-organic/. This one.
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I've answered it there!!
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Thanks for the help. Keep in posting more chemistry questions. I haven't posted one yet.
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Hey heating of Hydroxy acids does yield cyclic product but when the OH is at the\(\alpha\) position to the carboxylic group you get a six membered ring. Here it's at \(\beta\) position you get an elimination product. So I guess the answer is Prop-2-en-oic acid. Thanks. I thought both halo form and Hoffmann bromide won't follow although adding H+ in the next step is an indication that halo form follows to yield a carboxylic group. Thanks
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Try this which is somewhat related
https://brilliant.org/problems/fun-with-ketones/
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@Harsh Shrivastava @Spandan Senapati
Try This and help me with a solution!!
https://brilliant.org/problems/potential-of-a-conducting-cube/
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@Harsh Shrivastava @Spandan Senapati @A E a question
Electrostatic Potential at a point close to a charged conducting ball is V. When a very small conducting object ( a probe)
is brought at this point, potential of the ball changes by |deltaV|. Find force of electrostatic interaction between the ball and
the probe.
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What are the other parameters mentioned.....Like radius,charge on the ball etc.
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No Other Parameters. The Ans is 8pi(Epsilon)V|deltaV|
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I tried with the hint given at the back which says
"Charges induced on the probe due to the electric field of the ball constitute an equivalent electric dipole. The field of this dipole is responsible to change the potential of the ball by an amount equal to potential created by the dipole at the center of the ball. Now consider interaction of this dipole with the electric field of the ball."
I considered that since the probe is very small the charge distribution on the ball is unaffected and i applied
F= p(dE/dx) where E= kQ/r^2
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Yes it will do.You get \(8π\epsilon V\delta V=F\).Just to state \(\delta V=kp/R^2\) and \(F=2Vp/R^2\).I was considering that probe was a point charge so I was getting a bit weird result.But its conducting. so fine.
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Could you try that cube question
https://brilliant.org/problems/potential-of-a-conducting-cube/
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@Spandan Senapati @Harsh Shrivastava Do u guys have any link to purcell electricity and magnetism 3rd Edition Solutions to exercises??
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No dont I have .I don't know ifits available.But you can post them here .
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Like David morin's book solution or answers to exercises are unavailable.But you can post the questions here if you have any doubt.
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Thanks. I will post if i hav some doubts.
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@Spandan Senapati @Harsh Shrivastava Do you have a convincing proof of the following fact?
A point charge is placed inside a random cavity inside a conductor. Then the sum of the fields due to the point charge and the induced charges is zero for all the points outside the cavity.
I read Purcell. It is written that ' if we somehow remove the outer surface charge ' and then they proceed to prove the result which is fine, but how do you remove the outer surface charge in the first place?
If i assume on the contrary that the point charge and inner surface produce field inside a conductor, then this is not even a valid arrangement. We have to prove the fact. We are somehow assuming its true and then giving the proof.
Could you explain please??
It is confusing.!
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You probably didn't get the statement right perhaps.It means that the outer part is shielded from the inner.Means that the field due to the induced charges(here it means charges induced in the under surface not on the outer ones)+point charge is zero outside the vicinity of the conductor.Like take a very simple ex a point charge is placed at the centre of a spherical conductor then -q would be induced on the inner one and +q(if neutral on the outer one).Then the field due to -q(on the inner surface) and +q(point charge ) is quite clear to be zero for outside points(r>R).A similar argument says that the inner part is shielded from the outer.It means that the field at (r<R) is independent of the charges induced on the outer surface.Got it?
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@Spandan Senapati @Harsh Shrivastava @Aniswar S K. Can you all please help me in thîs question .https://brilliant.org/problems/gauss-law-2/.What is the dirac Delta function and what is its significance here ?
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I could have seen the q but the link isn't active in my phone.You know Greens Theorem(Divergence theorem)??That's a important theorem in vector calculus.Given a function we can calculate the divergence through(say a given volume )and this must equal the change thought he surface bounding it.Mathematically the integral \(\int \del .v(x,y,z) dV=S\int v.dA\).Here the second part denote a surface integral.But when the function falls as \(1/r^2\) something becomes fishy in terms of the integrals not being equal.For that we need Dirac delta function.Read any standard book on vector calculus and you will get it.
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Sorry for disturbing ,but can you please tell me how do I solve questions related to parallel plate with moving plates.?
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Is it given in grîffiths ?
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Yes,Even even a more mathematical discussion if younwant then read Thomas Apostle(Multi variable calculus-vol-2).You will have it.
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Thanks !!
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@Spandan Senapati Why the outer part is shielded from the inner part for all possible shapes of conductors and cavities? What argument we use to generalize from a sphere to any shape?
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Hey it makes use of Circulation theorem.But the proof of shielding for an empty cavity is quite beautifully explained in Feynman's lectures..Its quite simple and uses some apparent symmetry of positive and negative charges.Try to read it or if you don't have I will try to explain.OK?
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Thanks!!. I read about the proof for shielding in empty cavity from Feynman Lectures.!
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OK nice.I will read griffiths .let's see what it says..So that it becomes more clear.
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The charge distribution inside the cavitiy occurs in such a manner that center of charge of induced charge coincides with our point charge. This happens so that electric field inside conductor is zero. The cavity along with our charge thus does not affect outside world directly. Got it?
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Hey harsh aren't we going along two different lines.The one which I studied makes use of circulation theorem and you say centre of charge.And if it coincides then the mathematical argument must hold(the one with the integral as I said earlier).And for a general cavity the distribution being arbitrary we can't go on to evaluate the integral right.So circulation seems to be a cleaner argument.Isn't it?
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Oh yes proving center of charge coinciding with +q is hell tedious. So the work done in round trip method is quite good.
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Yes...And that's why coq as a concept isn't quite mentioned even in best books.there has to be symmetry to a great extent coupled with mathematical exactness.
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Where can i read about Circulation Theorem?
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Itry electromagnetics by Griffith's.Better have some basics of Vector calculus.Thats surely gonna help.
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Thanks!!
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Hey you qualified for Incho right.Can you tell what preparation is needed for chemistry Olympiad.I am gonna try to qualify it this time.
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I mainly did Archive for first level.
For second level i was doing previous year incho papers, old icho papers and preparatory problems.
For some special topics in organic chemistry like sulphur, silicon and phosphorous; radical and carbenes, heterocycles, Clayden is good.
After seeing the inorganic questions i was stunned. Maybe they expect us to guess new reactions based on our knowledge.!
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Nice I too study clayden.Thats a great book.So you must have like known the key concepts beforehand...So inorganic was tough this year.I saw that deuterium q.The first few ones seemed essy .Involved a little of modern physics.But further oneones were comparatively difficult.
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How much special theory of relativity should we know before reading Purcell magnetism??
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My Sir also gave this explanation but didnt explicitly prove it .!
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I think that if the COQ was not coinciding then a PD may arise inside conductor which is bad thus they have to coincide. Is there any flaw in reasoning here ?
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@Harsh Shrivastava@Aniswar S K@A E.Do you guys have a smart solution for this problem "Conversion of Algebra To Geometry is an art".My method was quite lengthy although I got the and.
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How many tests in FIITJEE do you guys have? We have our first coming Monday and will probably have one in every 2 week.
@Spandan Senapati @A E @Aniswar S K
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We too have it this Monday
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We have abt 1 every week.Actually our course is on a full swing.So they prefer teaching more and sometimes we have tests.Now we are in Biomolecules(last chap of organic),Maths definiteint over physical magnetism abt to be over.
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Good we arvery behind than you, in physics capacitors just started, in chem aldehydes started and in maths inverse trignometry abt to be started.
Hey let's post any good question if we come across in our tests OK?
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Ya sure that's a good idea...
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Oh I solved that long ago.Nice problem.H ow did you solved? I used Fermat point.
Whenever it comes for finding minimum distance inside triangle go for Fermat point. It is the point from where sum of distances to the sides is minimum. And here construct triangle with sides (0,0);(0,5);(12,0) and then find Fermat point which is the point such that <APB = <......=120°. I had a PDF which provided an awesome proof of it.
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Yes I too used the concept of Fermat point but rather than finding the point I used cosine rule and a little manipulation.
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@Spandan Senapati https://brilliant.org/profile/david-xee9sl/sets/gauss-law/37253/problem/more-gauss-practice-hard-2/ how to solve this??
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@Spandan Senapati - I got 66.75 in Aptitude test and 73.83 in Interview. The interview should have gone better!!
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@Harsh Shrivastava.@Aniswar S K.What are your marks in Kvpy?...The marks are available now.I got 72.75 in aptitude and 87.71☺in interview.Net 76.49.
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@Spandan Senapati do you know sarthak behra's marks? I got 69 in apt and 96.14 in interview
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Awesome interview bro!
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Thanks!
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Yes he got 82.5 in aptitude and abt 77in interview.Another friend of mine got 77.5 in aptitude and 78 in interview.She is air-17.Although that still amazes me how she got such a nice rank.
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thanks for the ranks! I am planning on running some statistics on it. Why are you amazed by her rank?
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cause she herself agreed that she cheated from me.See our roll now are just consecutive.I didn't notice that as I was busy solving.And like she expected 55-60 in aptitude.
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oh my..... thats quite bad
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This is the first time i am hearing someone getting >90 in interview . Well done
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@Prakhar Bindal Thank You! It was due to my interview I could get a very nice rank.
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Congrats...I am amazed by your interview score.To add a bit more to stats air-2 had 90 in aptitude test
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me too. what are his interview marks (air 2)?
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I Don't know exact figures.Just aptitude marks I knew.AYou expected a top 50 rank BTW?
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Not at all! I was expecting around 120-170 rank with my aptitude marks..... but the interview increased my marks by a huge amount
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Well congrats a pretty high score in interivew.
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Awesome bro!
I got 52.5 in aptitude and 63.2 in interview thus overall 54.99 (😢) if only I had one mark more...
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Dont worry dude. One of my friends didn't qualified last year . this year he is in top 50
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I really feel sorry for you....Just 0.01....Doesn't matter..go ahead.. you are gonna kill SX this yr.
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Why is induction due to point charge not considered here in this problem?
@Spandan Senapati @Aniswar S K @A E
This Problem
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If that were to happen even then in symmetric distributions the net charge must be sigmaArea(for planar surface of course)If it induces charge On a certain surface then on any other it must be q and summing all these gives q.But unlike a spherical symmetry where the induction of charge would be symmetric the system given here might have different densities at diff point(if consider induction)and may be calculating the force becomes tedious by integration.So again physics is all assumptions that you make.For a sphere although using Image Charges is the most apparent way.
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@Harsh Shrivastava. Did you also have reshuffling test today??.What's your score.Chem answer key is incorrect in Mains.So haven't checked.So my marks Maths-106/120,Phy-96/120.Adv-Phy65/80,Math-60/80.Yours??
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We didn't had any.
How was the paper? tougher than previous?
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Fine.Mains Physics was good yes both Maths and Physics were tougher than previous ones.Chem answers were incorrect in Mains so I didn't check..Have the prev ones results been released.I visited the microsite but what's Blind School.
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@Spandan Senapati and @Harsh Shrivastava - do try this question
https://brilliant.org/problems/permutations-in-organic-chemistry/?ref_id=1343394
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Thank You very much @Harsh Shrivastava and @A E.
You will definitely qualify next year.!! Cheers.
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Hope to do so.
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I could not qualify :(
Congrats @Spandan Senapati @Aniswar S K
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No problem...Just chill...Better luck next time.SX is still there..No rejoicing for me as well.Have another reshuffling test on Sunday.
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@Spandan Senapati most probably i will come. What about you??
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@Sarthak Behera.Great job buddy.You once again have made a stance...
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@Spandan Senapati, @Harsh Shrivastava My rank is 119.
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@Spandan Senapati Congrats for AIR 24 and Sarthak Behera AIR 4..
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Congrats to you as well...air 119 is great as well.You will come for Vijyoshi??
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Congrats @Spandan Senapati and @Aniswar S K
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Thanks lot...
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Do go there . Its worth going there . you will enjoy a lot and there will be fun + learning . Moreover your courses will be over by that time and only AITS Will be left hence no lose of fiitjee will be there. It was an unbelievable experience which i will cherish whole of my life
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Yes I will.Bhubaneswar is quite close to Kolkata.It takes abt 6 hrs in a train and 30-40 mins in flight.
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Cool Indigo took 2 hours while spice jet 2 hours 15 minutes from delhi .
Trains took a full day as due to fog in northern india trains were late by 12 hours :P
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@Spandan Senapati Could you please upload a solution to the seiche problem??
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Hey @Harsh Shrivastava.Did you also have batch reshuffling on 26th h.The one with a easiest phy in jee mains and a good jee advanced paper.Is it 1618 CRP ABC LOT RT-1??We had it..
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How much are you scoring, if you want answer keys, you may check Fiitjee Bhilai microsite, click on batch formation test result link and then proceed.
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Yes we too have got the answer keys.Mine score 300(Mains)115/88/97(PCM).And 125(adv)(46/31/48)(PCM).Total 425(main+adv).What about you??
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I feel like few answers are given wrong.
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Your chem adv is great....Although that was difficult..yes area are wrong.I found 3(main+adv).And the phy in mains was quite easy.Couldn't score full.:(And maths yes same.
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I also commuted various mistakes in mains and in advanced, I lost 2 questions in maths due to my carelessness have to becareful next time.l
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271 in mains(102/75/94)
132 in adv(38/46/48)
Our scores in maths are quite same I have seen in many tests :P
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Did you ever get full marks in class 11 fiitjee ex