iam currently doing masters in engineering(plasma physics),but i did my bachelors in pure physics.now is it possible for me to do phd in theoretical physics?hoping for great answers.
You can absolutely do your Ph.D. in theory, it's just a matter of where. The question is, what are you going to do after you get your Ph.D.? Only 10% of theory grad students are still doing theory 10 years after graduation!