Monday, August 25, 2008

Physics - Mains (Part I)

I have secured 378 (208 + 170) in Physics in CSE 2007. I had 269 in CSE 2006. The improvement was primarily due to emphasis I gave to answer writing practice during the attempt. I practiced (and memorised) most of the questions asked in past 15 years and prepared relevant notes.

Notes are a must
for this optional. Best way is to read a topic, solve past years papers and improve the answers to the best of your ability. The answers form your notes. Go through this process religiously. It will help because the paper does not give time to think. Only rigorous practice can help in writing answers well in the time alloted.


With some exceptions, most topics require more than one book. Pick up a standard text book for the topic (I'll mention mine topic wise below) and study the parts mentioned in syllabus thoroughly from it. For books for other topics follow borrow, beg, steal, buy policy in the correct order.

Quantum Mechanics: Textbook Ghatak. It's a tough book but I am happy about my choice. Atleast it does not give wrong concepts, only tough concepts. Covers most topics well. But here's what's not in it.

Exact proof of uncertainity principle: It does not solve the general case. But do it on your own. To simplify use properties of Hermitian operators which I did from a borrowed Gupta-Kumar-Sharma.Satya Prakash also deals Hermitian operators well. Do see and solve question on uncertainity principle in CSE 2004 examination.

Proof that Gaussian wavepacket is minimum wave packet: It is given in unsolved with hint but does not solve the equation. Be brave, go ahead and solve the differential equation. Do normalise the final result.

Ehrenfest Theorem: It is in unsolved with hint but in three dimensions using del operator. Solve it in one dimension using integration by parts. Or see solution from Satya Prakash.

Finite well: It solves the problem but it's much better in H C Verma Quantum Mechanics. Please read H C Verma for this.

Linear Harmonic Oscillator: Follow the book and reach till Hermite polynomials. The only problem is it's quite lengthy. So delete the part where the author proves that s = 1 is invalid. Start with assuming s =0 i.e. remove s from the picture altogether. Not correct according to rigorous mathematics, but we are talking Physics. This topic will require lots of practice to finish in the time alloted.

Hydrogen atom Problem is a head ache, but there is no shortcut. If a question is asked in examination, read it thoroughly and see whether it demands a complete solution or not.

Do operator algebra and Pauli spin matrices from Satya Prakash. It's a must

Atomic and Molecular Physics: Raj Kumar for Atomic Physics and Banwell for Molecular Physics are a must and good enough. Stick to the syllabus. The topic missing is "Importance of neutral .......". The only question asked till date is H21 cm line. Prepare answer on it from internet.

4 comments:

Neelam said...

Dear Sir, Great congratulations!
please suggest me some important books for Physics pre exams.

Thanks you
Waiting 4 ur reply.

rishu said...
This comment has been removed by the author.
rishu said...

sir can u tell me the name of the books for MATHS(pre and mains).i have decided to go with MATHS as my second optional,first is electrical...,plz reply sir.

parminder boparai said...

hi sir
i just went thru ur answers to 2007 physics paper after studying josephson effect from pillai
but i was still amazed by ur answer which goes beyond pillai and is better organised
i ll make 1 request which many might have made before me
please share the model answers u prepapred to previous year physics paper
can it be possible sir
my profuse gratefulness is otherwise also due for such an elaborate blog
parminder