After completing B.Sc Physics, You can apply for the courses M.Sc Physics, M.Sc Geophysics, M.Sc Nuclear Physics etc. as per your interest.

IIT JAM is the entrance exam conducted for different M.Sc programme, integrated PhD, M.Sc- M.Tech, M.Sc- M.S (Research), and other postgraduate programmes to get admission in IITs. You can apply IIT JAM Entrance for M.Sc Physics, Geophysics. You can the information about with the given below link.

https://university.careers360.com/articles/jam-eligibility-criteria

There are also many university level entrance exam you can apply.

Good Luck!