I have seen other similar questions, but this one is specific to applicants with a Masters degree. Because it seems that US PhD applicants with Masters are held to a higher standard.
Background
I have an Integrated Masters degree (Bachelors + Masters in 4 + 1 years) in Electrical Engineering (EE). My Masters specialization was in area X (part of EE), and I have 2 good publications in X.
I wish to apply to PhD programs in Electrical Engineering (in the US). However, I have two areas of interest: X (main) and Y (possible).
X = Microelectronic devices, Y = Electric grids, Renewable energy integration. They're quite distinct, but do come under EE.
Question 1
It is okay for undergrads to have multiple interests. But I have a Masters in X. If I am admitted to a US PhD program, am I allowed to choose my area (X or Y) at the end of my first year coursework, like those with only an undergrad degree?
Question 2
I ask the above question because I see that most universities reduce the coursework requirements for students who hold a Masters. Although I have a Masters, can I choose to do the full coursework? I think this would give me more opportunity to explore and choose between X and Y.
Question 3
Given that I have a Masters and 2 publications in X, does it look bad that I have an interest in Y as well? I intend to write about my interest in Y in my SoP.
However, I have a reasonable explanation. My underlying theme of interest is energy, which I can realize via either X or Y. They have their own merits and demerits, and I like them for different reasons. I just wish to take a decision after exploring both thoroughly in my coursework.