If you are preparing for JEE and want to clear your concepts in Physics then Concepts of Physics by HC Verma is the best book you can find. It teaches physics in a very simple language.
It has got sufficient number of illustrative examples and unsolved exercises at the end of each chapter. I will suggest you to solve the illustrative exmaples by yourself.
When you will consult your doubts with your teacher and find the solutions you will feel very confident in physics. This book is a must for enginering aspirants.