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The preliminary of the AIPMT was exclusively from NCERT. Will the MAINS b the same? (it will be tougher, but will it be excusively NCERT-based?) If no, could anyone please help me on the syllabus?
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@xeonax: I'll post it tomorrow... i'm too weary to draw th pic today! thnx neway!@akshay: well extra things are a no-no in this question. That includes water! And if u try for total internal reflection, i can;t make out how u will use the mirror ... u HAVE to use the remianing portion of the mirror! ... but plz elaborate a bit...since the question is now answered, u can post how u propose to use water... we cud all benefit.... and i thnk i shud remind we only assume the one-ray image thing for this question!! otherwise, that is a technical mistake (like I did in my frst post :-P)@akansha: It is a small barrier to ensure that light does not travel directly to the source point to the image point. If light went that way, there would be no reason we would bother with a scratched mirror at all :-P
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@deepak: Actually I have read that in modern quantum optics, light is considered particles in the best sense... "Quantum Electrodynamics"... (of which feynman was hmself a pioneer) .. ecxplains all these things in terms of photon behaviour... and since i got this in a buk of that subject, i am not sure if it can be explained by wave theory satisfactorily.. (I'll search a bit and then discuss this)..... Infact I am still reading the book.. so maybe i will have better understandging after completing... You can ask anyone who has read it full or similar such stuff..
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@xeonax:: Thnx .. ur pic was well timed! ... cud u plz go thru deepak's nudgebuk.. i have a doubt abt which i have posted smwthing... i havnt had a satisfactory explanation to that...
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@deepak: thnx... :-) plz check ur nudgebuk.. i have doubt on an answer..
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So what to do now is that you remove some more part of the mirror!!! do it carefully, by removing the silvering of the mirror in carefully chosen points so that the new "sum total path difference" from the source to the reflecting points to the image is ZERO...... this is a diffraction grating!!! What you achieve is that you weed out those reflected EMWaves which contribute towards a net path difference..... In effect,you have broken the mirro into smaller pieaces AND carefully adjusted the position of those mall pieces (since u are not allowed to move things here, u just pick the silvering) .... You adjust the net path differene to be zero, and you get an image!!!Do I need to put up a pic? (its a weary job u knw ;-P)
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@deepak: yeah! Individual photons of light travelling in one wave do not infact follow the laws of relfection as we follow them in the macro scene. What happens is that Light from the source falls on ALL available points on ANY surface available where it can go geometrically. After this, the light rays are diffracted by the particles of the reflecting surface BACKWARDS (in the same way that diffraction spreads out an incoming wave OUTWARDS).... now the rays are spread out in all directions and they follow ALL POSSIBL PATHS from the source to the reflecting surface to the image point. The image is seen because the path differences of all these 'possible paths' then add up in such a way that the image is seen with the same intensity as the object. (refer the diagram)... The path difference plays the main role here.. What happens when you cut the mirro is that you remove a lot of rays that initially cancelled path differences (resulted in no net path difference) from the rest of the mirror.... now the image does not form because the path differences now do not cancel each other.. (there is a net path difference).....
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@deepak: carry on with your suggestion of "breaking" the mirror... there is an er.. "moderate" way of doiung it too! ... Everyone, take a luk at the page posted by xeonax... Shall I post the answer?
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@ xeonax (or whatever) ::: you had to post that page right from the buk??!! huh! :-D @deepak: you came closest to the answer ... the laws of relfection infact are derived by treating the light as an EMWave that behaves as 'particles' when interact with matter.. in this case, the waves travel through air in every possible direction, then hit the mirro, interact with the atoms of the mirror as particles, then are thrown away in every direction as waves, as shown in th page posted by xeonax... (it is from the buk which i mentioned)... @Vivek: close, but rather than making it rough, we got to do something further, bacause diffuse relfection does not follow any law. You cannot predict anything from something that does not behave as you want it to behave! .. but what we do is equivalent to making it rough. But as i said, diffraction is how we understand it best.
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@raj: oh never bother! this is just for the delight of the unconventional solution that Feynman teaches in his book. (I dont think i have the least chances into JEE with just a likeness fr these kind of thngs) .. I'll give the answer at 9-10 pm today then... Last hint if u come online within this time: "DIFFRACTION"
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@optimus: could you please explain a bit? If you are talking about bending the light ray by refraction, then it is not a general solution, because the general solution works for ALL casses, whatever the length of the cut-mirror. Also, this solution requires (as mentioned in the very first post) that no extra things are to be added, and that includes water too! But I agree the method would work for specific situations when addingof water etc is allowed. We can use a block of any material with the right optical density placed in front of the mirror to bend th rays as we want, but this is not the case here.
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@ deepak: you are slightly on the right track in the fact that you are thinking EM waves characteristics.. but here, we rather manipulate the reflected wave than tampering with the incident ray/wave ..... but plsz let me know what was on ur mind... every problem has multiple solutions... i'd love to hear one.
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@ deepak: you are slightly on the right track in the fact that you are thinking EM waves characteristics.. but here, we rather manipulate the reflected wave than tampering with the incident ray/wave ..... but plsz let me know what was on ur mind... every problem has multiple solutions... i'd love to hear one.
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@deepak: you are slightly on the right track in the fact that you are thinking EMwaves properties. But this one has to do with "manipulating the reflected wave" rather than "tamper the incident ray". But could you please tell what you were thinking? there are alternate solutions to everything and I would be love to hear them.
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@deepak: you are slightly on the right track in the fact that you are thinking EMwaves properties. But this one has to do with "manipulating the reflected wave" rather than "tamper the incident ray". But could you please tell what you were thinking? there are alternate solutions to everything and I would be love to hear them.
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@deepak: u r slightly on the right track in the fact that you are thinking EMwave characteristics, but this one involves with manipulating (rather than tampering) the reflected ray, not the incident. But could you please elaborate what you were thinking? (there are alternative solutions to almost every problem and I would love to hear it)
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@ EL: yeah.. i'll probably give th soln in a day or two.
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@raj: absolutely! you can't 'move' the mirror! ... but you have to do "something" to it! I'll repeat that th answer is quite odd! want it?
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ok, a couple of final hints:: forget the WHAT of the laws of reflection, and think WHY the laws of reflection......... and you have to do something to the mirror... something very odd
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yeah Aakash. thats right. In the case of electrostatic potential energy (EPE ok?), the term EPE of the ball refers to the EPE of the 'Charge configuration' on the ball. This means, when you start adding up the EPEs concerned, for the very first case, you take a 'zero' charge on the ball and find the EPE of this configuration with another unit differential charge brought from infinity. Gradually, during each 'unit summation' of the integration you do, you are calcuating the EPE of a specific charge configuration in each case. Thus, as you said, the EPE of the 'ball' alone as a singl object is wrong, but EPE of the ball as a 'charge configuration' in all the concerned steps agrees with the fact that only a 'system' can have a 'potential energy'. In some cases it might be two objects, in some cases it would be more.I hope this is allright?
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