Hi Praveen,

I assume that you are from class XII CBSE. The chapter Modern Physics doesnot hold much weightage in most exams (including Boards, NEET, JEE Mains). Though, it is an easy chapter and can help you score marks without losing it to negative markings. 

Semi-conductors is a topic that holds weightage mostly in Boards and are majorly ignored in the preparation of competitive exams. The questions asked from this topic in competitive exams can be answered with basic knowledge of Chemistry too. 

Whereas, Current electricity is very important in both boards and competitive exams. The topic has so much potential for conceptual questions (both in objectives and application based) and also derivation & defining type of questions. 

You can check youtube videos to make the concepts of these topics clear.

All The Best.