For appearing for IIT JAM for Physics, according to the eligibility criteria mentioned in our article: https://university.careers360.com/articles/jam-eligibility-criteria , you should have completed your Bachelor's degree atleast with Physics for 2 years or 4 semesters and Mathematics for 1 year or 2 semesters. So if you fulfil this criteria, then you are elligible for appearing for IIT JAM 2021. If you are enquiring about Age criteria, there is no upper age limit for IIT JAM.