Many high level technical positions require a Master's, and if a life of research is your passion, then a Ph.D. is almost always required. An economic benefit to grad school is that many programs, especially Ph.D. programs, pay for your education and more. You can earn your advanced degree for free and be paid as a teaching or research employee of the University.
You can apply to either a Master's program or straight to a Ph.D. program in your senior year. If your academic record could use a little strengthening, you may choose to apply to a Master's program as a stepping stone to the Ph.D.
Always feel welcome and encouraged to speak to any faculty member about graduate school or the career that you're interested in.
GRE Physics Test overview