Good luck on your interview tomorrow. I wouldn't worry too much about being in different industries. I am finance and my interviewer was IT, but it didn't seem to hinder the conversation. I imagine you will spend most of the time on broader topics related to Columbia than anything singularly related to Finance. Don't hesitate to mention specific finance related courses you are interested in because even thought the interviewer might not be familiar with them, it shows that you've done research on Columbia's programs. When it comes to your future career goals and why, the interviewer might not ask too many follow-up questions if they have no idea what the role are describing is, but that shouldn't be counted against you. I think they care more about you demonstrating that you have a clear path in mind.
My interview lasted exactly an hour because it was during the business day and he had a conference call scheduled after. I get the feeling that most are around an hour, but I wouldn't obsess over a little more or less.
I would recommend you prepare questions for them too. I think broad and "experience" based ones are best - "What was your favorite aspect of XYZ" or "What was your most impactful experience". They obviously had a good experience or they wouldn't be volunteering to interview and everyone likes talking about themselves.
I think this is posted on every site/article about interviewing but show up early and bring extra copies of your resume!
Good Luck!!
