As "Phobos" who is PF Mentor has advised me to post my message here, it is as below. I'm a design engineer. My qualification is MSc Physics. I want to complete higher studies to understand the designing and working of switch mode power supplies. Should I do PhD in Physics or choose electrical engineering( Power electronics) for that. Which one is better. Please refer to "Career in Engineering" at Electrical Engineering forum as well before answering my question.