Tuesday, 27 May 2014

It's "optics", can't you "see"

Optics is considered as one of the simplest portion in JEE syllabus.
Optics requires quite a bit of memorization and a good command over
basic high school mathematics (mainly geometry and algebra). One
should be comfortable with calculating unknown angles / distance etc.
The problems in optics are generally simple and easy to solve. But
there is an obstruction on the way – silly mistakes. Since the
questions are mainly mathematical, it’s very easy to make silly
mistakes. So, it is advisable to practice plenty of questions from
Also, there are quite a bit of formulas involved in geometrical optics
part (u-v formula for lenses/mirrors, laws of reflection and
refraction, etc). So, it’s better to understand the derivations as
well which will surely help in tough situations.
Keep in mind that optics portion has a huge weightage in JEE and so, a
candidate aspiring for a good rank cannot afford to give away marks so
As usual, we will go chapter wise (as mentioned in JEE syllabus):

•       Rectilinear propagation of light: This portion mainly includes the
elementary properties of light. The basic properties about the nature
of light coupled with laws of reflection and refraction form the basic
framework of the entire optics. So, students should understand these
topics very well and practice ample of questions. Simple ideas can be
effectively used to frame complicated questions but those who have a
good understanding of basic concepts won’t face any problems.
The ideas of total internal reflection and deviation of light by a
prism are simple but slightly theoretical. So, one must read enough
theory for these concepts. Good questions are asked from total
internal reflection and the questions asked are generally “new” ones.

•       Reflection and refraction at plane and spherical surface: The ideas
covered in the last chapter will be improved and the concepts of
reflection and refraction at curved surface will be introduced. As
before, the ideas taught in this chapter will be used in the next
chapter. You will be taught a couple of equations which will be used
to predict the path of reflected/refracted ray. There will be a few
derivations involved which are simple yet important and must be
understood very well.

•       Spherical mirrors: The idea of reflection of light will be improved
upon to develop the idea of reflection of light from spherical
mirrors. A new equation called the u-v equation for mirrors will be
introduced. There will be several cases of position of objects and
associated images. Students must keep in mind the properties of images
formed for a given position of object. The idea of lateral
magnification helps a lot to predict the size of image. Proper care of
sign convention must be taken to avoid silly mistake.

•       Lenses: The idea of refraction of light at a curved surface will be
used to build up the concept of lenses. A new equation called the u-v
equation for lenses will be introduced in this chapter. Note that the
u-v equation for lenses is quite similar to the u-v equation for
mirrors. So, students should ensure that they do not interchange the 2
equations while solving problems. It’s very easy to make silly
mistakes here and it has been seen that even very vigilante students
make mistake here. One must take care of appropriate sign convention
while solving questions of lenses. Mind bending questions are also
asked from combination of lenses. One must keep the idea of “power of
a lens” in mind while solving problems of combination of lenses. The
idea of “effective focal length” helps a lot in solving problems
involving lenses separated by a distance.

•       Combination of lenses and mirrors: Most questions of optics are
asked from this portion. If the student is weak in any of above
topics, he/she is likely to face problems in solving JEE questions. So
to solve (apparently) complicated questions, students should focus on
the basic ideas taught in the previous chapters and integrate them in
the correct way.

•       Wave optics: “Huygen’s principles” form the basics of this chapter.
The idea of wavefront is the basic idea and must be understood very
well. Students tend to ignore this portion and the JEE paper setters
are pretty much aware of this so they have started asking very good
“paragraph” type questions from this portion. So, avoiding this part
may significantly affect your rank.
Next comes the famous YDSE – Young’s double slit experiment – a very
important idea. Every year there is at least 1 question from YDSE.
Very frequently questions on “modified YDSE” are also asked. For
example – a glass slab is introduced in front of 1 or both slits. The
key to solve this problem is the idea of “phase and path difference”.
Students are advised to practice variety of questions from YDSE

To summarize, optics covers a variety of simple ideas which are very
common in JEE. So, students aiming for a seat should not ignore the
optics portion. Solving as many problems as possible will surely help
you to get a firm command over optics portion.

Recommended textbooks: HC Verma, DC Pandey, NCERT, Resnick Halliday 


  1. Hi,,
    I posted my question earlier too...
    How is dual degree(B.Tech,M.Tech) 5 yr at IIT BOMBAY IN CSE..
    Or shiould i take B.Tech CSE IIT KANPUR???? PLEASE REPLY

    1. Iit bombay no longer offers dual degree course in cse
      So you don't have the option of dual degree 5 year iit bombay cse

    2. Hey Aman...
      I am getting IIT Kanpur CSE...
      But I always dreamt of IIT DELHI CSE...SO,I AM PLANNING TO DROP...
      Is It wise...As far as placements of droppers are concerned...

    3. Well
      That would be called as "being Crazy"
      Listen my friend
      Iit kanpur cse is world renowned
      It's no less than iit delhi cse
      Please don't make mistake of repeating.
      You will surely cry if you repeat
      Mark my words
      Don't even think of repeating!

    4. Aman is right......delhi is more famous just because it is in a metro city...go for kanpur

    5. How do u know that u r getting iit k cse???

    6. Thanks Aman,,,one more question??

    7. Thanks Aman,,,one more question??

  2. Hi Aman
    please read about my current situation and answer
    My expected rank in IIT is 5000. so it's not possible to join any good IIT. I feel that i am more deserving than these rank and the main reason for so low score behind these is that i got very less time for my preparation as I had do coaching and had to simultaneously go to school almost regularly for these 2 years So according to you what shall I do join in some NIT and prepare again or drop one whole year (before answering keep in mind i am very much prone to hypertension) ? Do droppers face problem in placement ( in IIT )
    Sorry for asking it here as i could not find any correct place to ask these question

    1. No issues my friend
      Well see, I have no idea of "problems faced by droppers in placements". So I don't have a word here

    2. thanx for your prompt reply
      You didn't answer my first question i.e. according to you what shall I do join in some NIT and prepare again or drop one whole year (before answering keep in mind i am very much prone to hypertension) ?

    3. Well I don't know about that.
      I really don't know what to comment on this.
      I am sorry for that

  3. hi aman bhaiya
    please reply to this query of mine which i posted earlier too...
    I read ur post for olympiads aman bhaiya. i have started solving IE IRODOV
    but I need a good theory book to complete class 12 syllabus along with my current class11 for nsep. Furthur after viewing past years kvpy papers i found maths section very tough and time consuming as it contains questions mostly from algebra. can u also please suggest me a good book for it as i m finding TMH insufficient for kvpy preperation?
    Please reply at the earliest.

    1. Theory book: HC verma, dc pandey, Resnick Halliday
      Well Tmh is one of the toughest nook for maths. If that's not enough, then nothing would be enough

  4. congrats aman bhaiya,
    saw the marks of ur followers who have really done well following ur excellent guidance!!!!!

  5. its the final request from u. i have already posted my query on 24 may.kindly listen.

    1. In which post did you post your query?
      I am sorry for the delay
      Maybe I overlooked it.

  6. Brother u r last hope and its my final request too from u. I have addressed u my query three times in the posts of today and 24.I have no guidance and each passing day is throwing me out of competition. Please help me!!!!!!!!!!!!!!!!!!

  7. Aman Bhaiya, Again a nice post :)
    Please see my few queries
    One of my seniors at IITB told me that, IIT B outshines all iits in terms of exposure and oppurtunities abroad!
    Is it correct?
    Also are the CSE course structure is different at all iits!!

  8. Diffraction and polarisation of light are not included (at least not written specifically, but even thin films aren't written specifically), in the syllabus of optics for JEE advanced 2016 in the official site (http://www.jeeadv.ac.in/scr/syllabi.php), but they are given in so many books and even in my FIITJEE modules. So I am a bit confused should I study them or not. I thought I'd check here if there is any word on it or not. As there was none I thought it best to ask you, I am a dropper so should I study these topics?

  9. Replies
    1. No he cleared JEE ADVANCED in his first attempt air 33