This question is asked by my student Kanhaiya Kumar, let’s start discussing !
If demand is clear, then will be able to supply the things otherwise we are just guessing the way to crack Interview.
What the Interview Panel wants from you ? I have 2 aspects to share, let’s discuss it one by one.
Aspect 1 :- They already knows, you cracked some precious exams like JEST, TIFR, JAM. They don’t want to check those things again, may be a thing can be in their mind is somehow by learning some tricks, formulas you cracked these exam, so what they want is you knows Physics behind or not. So, you must ready for some questions level to these exams just for a clarity you knows concept behind it.
Aspect 2 :- What you are going to do in Int PhD ? Obviously 2 things are there one is coursework and other research work, for coursework if you cracked these exams, then you will be able to clear those coursework, so that was not their POV , in interview they checks your eligibility for research work. They just want from you that you are fundamentally sounds in Physics, you have Research Aptitude, Your Mathematical Thinking is Good, your graphical analysis is good, you think out of the box, what is your approach for a new situation or problem, you link Physics fundamentally or not, are you able to connect the dots, thats all. Apart from this, they also wants a person whose goal is long term, means he/she should not leave mid way by taking just MSc degree, he/she is not here for just fellowship, he/she must have enthusiast for research, they can give 6-7 years to us or not.
I am not talking more, leaving hints to create a picture, hopefully you have drawn a big picture here, you now understands what I am trying to convey you. “Mai Bol Kam Raha Hoon, Tum Zyada Samjho”.
Now another part is collecting resources, I divided it into parts.
Resource 1 :- Collect previously asked questions, so best place find it on Quora, some other websites, YouTube Video of Interview Experience, note all the questions that have been asked. Now, understand one thing, Interview Panel may vary, Institute may vary, but Physics is same, and to check eligibility for research work is also same, so the diagnosis process is simple, questions you have collected is enough, just prepare them. What I will do in future in our PhysicsDost platform, will provide list of Questions and will conduct question answer sessions.
Resource 2 :- You cannot prepare those questions like an objective examination, you need to prepare it subjectively, you must understand Physics behind it, for this you need to read some standard books like Aurther Bieser for Modern Physics, Griffiths for Electrodynamics, Statistical Mechanics from BB Laud, Reif or RK Patharia, for Solid State Physics my Personal Recommendation is SO Pillai, some Mathematical Physics Book not like HK Dass more standard, Quantum Mechanics from Feynamnn Lectures Volume 3.
This is all Demand Supply game, understand it, work on it.
Good Luck !
A YouTube video of Mine also helps, I talked here elaborately, some more points can adds up, watch here https://youtu.be/wYjbN1l_-Ek