Maybe explain how you mean, "grad school" or PhD program.Is it common for physics grads to change the topic of their research focus (staying within physics) while at graduate school?
"You" who? josh0768 is an undergraduate student according to profile page. I already have a degree , something beyond highschool which I already graduated years before that.Why do you need to know, given that you are still in high school? As pointed out "graduate school", "topic', "focus" can mean many things. If you could be clearer in the question, you might get better answers.