Which topics should I focus most for physics class 12 CBSE board exam?

Hey.

Some important topics are as follows,

1. Wheatstone’s network
2. Metre bridge and potentiometer numericals
3. Ampere’s circuital law and applications
4. Biot-Savarts law
5. Moving coil galvanometer
6. Cyclotron
7. Gauss’ law and applications
8. LCR circuit in resonance
9. Power dissipated in a series LCR circuit
10. Block diagrams from communication systems
11. All the theories of semiconductor chapter
12. Lens makers formula
13. Ray optics numericals ( image formation)
14. Interference through single slit
15. Young’s double slit experiment
16. AC generator
17. Mutual induction due to solenoid
18. Transformer
19. Derivations from electrostatics
20. De-broglie wavelength
21. Atoms and nuclei derivations of radius

These are some of the direct question which are very important that might pop up in the board examination.

Hope this helps.