Hello dear, 

The trend of question setting changes every as previous papers are set by cbse now the question setter is NTA. So they can ask from any of the topics so it would be better to go through the topics thoroughly but there are topics which should more focused after going through all the topics like electrostatic, Atom and Nuclei, SHM, magnetism,EMI ,waves optics,etc.for more topics you can check the link provided -

https://engineering.careers360.com/articles/jee-main-important-topics-books/amp

Hello,

Must read topics in Physics section for JEE Mains is:

( a) Magnetics

(b) Electromagnetic Induction and AC

(c) Current Electricity

(d) Waves

(e) Electrostatics

(f) Oscillation and Waves

(g) Modern Physics

(h) Optics

However, this is just a narrow view and not the only topic that are imporatant

Go throughthis link for more information on Important topics in physics: https://engineering.careers360.com/articles/best-books-for-jee-main-2019

For complete JEE Mains Syllabus: https://engineering.careers360.com/articles/jee-main-syllabus

For official JEE Mains Syllabus: https://jeemain.nic.in/WebInfo/Handler/FileHandler.ashx?i=File&ii=33&iii=Y

Please Note: JEE Main 2019 for April session will be conducted on April 7 (Paper 2) and April 8, 9, 10 and 12 (Paper 1). 

Magnetics