Some are, the one I have (which is titled AS & A2 Physics, Exam Board: AQA A) is far more useful and informative than the textbook provided in school. Personally, along with my teacher's valued opinion, the current textbook has to be the worst book endorsed by AQA in some elements it is too brief and occasionally misses things out all together. Also another book worth getting your hands on is Practice in Physics: Fourth Edition, it is full of practical knowledge and questions which stretch you. They worked for me as this year I started with a D and now I'm comfortably at A so definitely worth considering!