How to clear concepts of physics?
First of all, read from good books. So, if it’s school level, icse and CBSE books are good. Similarly follow some standard books in your BSc or MSc.
Practice a lot of problems. Understanding and solving the problems is more important than just knowing the theory given inside the chapters of the book. Good books have a beautiful set of problems that will enhance your understanding of concepts.
Physics is a wonderful subject and very interesting to learn. Don’t ever mug up stuff. Understand the theory, make it sink in and picturise stuff whenever you can.
Clear your doubts immediately. Discuss actively with a faculty member. That would be the best option. However, you can also form groups with your classmates, but make sure that these groups involve people who really want to learn the subject and not those who would sit around to chat useless gossip.