Magnetic Effects of Current and Magentism topic carries an overall weightage of 6% in WBJEE Exam. The chances of questions not being asked from this chapter are possible but you cannot ignore this topic. Because in JEE Mains, repetitively there have been questions asked from this chapter. So if JEE Mains is also in your exams list, you cannot skip this chapter. Your focus should be on topics like:

Current Electricity

Electrostatics

Heat and Thermodynamics

But that doesn't mean you can skip this topic. Atleast read it once and revise it once so that if there is a question that is asked from this Unit, you know how to answer. Study about Polarization, Interference, Reflection, Diffraction. Also study Cosmic rays, gamma rays, microwaves, etc. Just make a short notes of these topics and then revise them. This is just to keep yourself prepared. With competition increasing year after year and cut offs going way higher, you do not want to miss out on marks just because you thought the exam paper wouldn't have those topics covered.