Remember this advice isn't official. There is no guarantee it will reflect your experience because university applications can change between years. Check the official Cambridge and Oxford websites for more accurate information on this year's application format and the required tests.
Also, someone else's experience may not reflect your own. Most interviews are more like conversations than tests and like, any conversation, they are quite interactive.
Test taken: Physics Aptitude Test (
Number of interviews: 3
Time between interviews: Hours - two on one day (morning and afternoon), one on another day.
Length of interviews: 40-50 mins
Online interview: No
My interviews focussed heavily on Physics/Maths problem solving questions (like the PAT, but sometimes more open-ended, or solving for general cases). I was not asked about my personal statement in any of my interviews. The only deviation from this was in the last interview (at a different college). They asked me to talk about some physics in the news that interested me, I think as an ice breaker.
Went over tricky PAT questions, read through my personal statement, practised problem-solving physics/maths questions,
Practised all the past papers on the Oxford website, marked them from a free online answer bank found on Google. Also attended a PAT workshop put on by a private company (my state-school managed to get it heavily subsidised).
Practise as many PAT questions as you can - then do other problem-solving-style Maths/Physics questions. Google examples of Physics interview questions, and go through them/read around the subject. If you can, try to have a go at a mini-interview-style discussion of a question