How many questions should i prepare for a 10-15 minutes long interview?

This is one time you should "over-prepare". Think up at least twenty questions, in several categories. Say you have five main categories – have five questions for each. Be prepared to move along to the next category after two or three questions, in case the interview isn't very productive with the first category. Brief or uninterested replies would take only a minute or so, while good questions might lead to a discussion that would take four or five minutes.

Don't worry if only a few of your questions get discussed. That would mean it's a good interview, where the other person was genuinely engaged with the subject matter. Cast your mind back to some good interviewers you've seen on television, and pace your interview like they do. Strike a balance between staying a little longer with one topic if the interviewee has something interesting or vital to say, and moving along if he's just blowing hot air.

I would recommend doing more than you think you need. I would probably write out 20. The thing about live interviews is that sometimes you can get stuck on one question, or one question can kind of lend itself into the next one. Interviews are basically like having conversations, with you for the most part being the listener. So if your subject says something interesting, you can always ask a question from one of their responses. If you can, research your interviewee as well and find out some things about them, so you can better formulate your questions. It will help if you have some background knowledge going in, that way you can think of thought provoking things to ask, that are relevant. Versus stock interview questions that can get tired. I think you may find, that if the interview goes well, you may not have to improvise, it will come naturally. Just prepare yourself some questions just in case you get stuck.

15 Minute Interview Questions

It depends on the scope of the interview. An interview is not just questions and answers, it's taking the lead and turning an answer into another question.

Most of that you can't plan for. A simple question and answer situation can be done via e-mail if you don't want to add personal interaction or editorialization.

Depending on how long the questions will take to answer, you can most likely get away with 6 questions.