Hello,

For joining ISRO as a scientist you should have at least the Msc degree or Btech. the Msc degree can be in Physics, Chemistry or Mathematics. For joining as ISRO Scientist - SC (entry level ) basic education qualification is Msc or Btech. As you are student of Bsc physics i will suggest you to complete your Masters in Physics. Otherwise you can follow the following way also,

After Bsc physics you can join as Technical Assistant, ISRO allow you option of part- time / correspondence study and after completing Msc you can get promoted to scientist -SC

Hope this answer will help you

Good luck