Pls answer
Yes of course you can join ISRO after MSc in Physics. And you can follow following steps.
First finish your BSc and MSc with first division/65% marks/6.5 CGPA on a scale of 10.
There exists ISRO Centralised Recruitment Board (ICRB) which conducts an entrance exam.
Log on to ISRO's website and look for Vacancies/Recruitment option and check for any position of interest.
Register for the exam.
Look at the pattern of previous year papers and prepare well.
Once selected, you will get a call for an interview.
Clear the interview.
Join ISRO.