Hello,

Your question isn't complete, you haven't mention whether you're asking this question in reference to 11 or 12th Standard or for any entrance exam, in case it's for JEE Mains, I've mentioned below-

In order to know which topics to skip, it's good to be well acquainted with important topics, it'll give you a fair idea about what's important and what's not-

For physics, the important topics are as follows-

Circular Motion, Center of Mass and Collisions, Communications Systems, Kinematics, Laws of Motion, Rotation, Electrostatics, Current Electricity and Capacitors, Magnetic Effects of Current and Magnetism, Electromagnetic Induction and Alternating Current, Bohr's Atomic Model, Waves  and Sounds,Units and Measurements, Work Energy and Power, Fluids, Nuclear Physics and X-Rays, Heat Transfer, Gravitation, Wave Optics, Ray optics, heat and thermodynamics, photoelectric effect, semiconductors, oscillations, electromagnetic waves.

Hello Pramod, You need to mention which exam you are talking about. But for preparation of any exam, you should not skip any of the topics. You should check the syllabus for the examination and then prepare your notes according to that because in exams like JEE Advanced, there are many topics which are removed and added each year.