reflection

I got the question right but I am not sure the specifics of why I would choose this answer. It was more of a gut response. At what incident angle (θi) does a ray have to first hit the collection face to end up traveling directly up the fiber (up the page in Figure 1)? A. 0° Correct...

When taking the 2009 DAT QR section, I had trouble with all of those reflection questions. Do I need to study these before my test? And could someone maybe explain how to do them or a good site to use to look them up? Thank you in advance!