Class 12 Physics has a reputation for being the hardest CBSE subject. But the truth is: CBSE Physics is completely predictable. The same types of questions appear every year — derivations, numericals, and diagram-based questions from specific chapters. Master those, and 70/70 is within reach.
Chapter Weightage for CBSE Class 12 Physics
- Unit 1 – Electrostatics (Ch 1–2): 16 marks
- Unit 2 – Current Electricity (Ch 3): 17 marks
- Unit 3 – Magnetic Effects (Ch 4–5): 18 marks
- Unit 4 – EMI and AC (Ch 6–7): 20 marks
- Unit 5 – Optics (Ch 9–10): 18 marks
- Unit 6 – Dual Nature, Atoms, Nuclei (Ch 11–13): 12 marks
- Unit 7 – Electronic Devices (Ch 14): 7 marks
- Practical: 30 marks
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EMI and Optics together carry 38 marks. Prioritise these two units above everything else.
Must-Learn Derivations
Every year, 3–5 derivations appear in the CBSE Physics paper. These are your guaranteed marks if prepared well:
- Electric field due to an infinite plane sheet of charge
- Expression for capacitance of a parallel plate capacitor
- Biot-Savart law derivation for a circular loop
- Force between two parallel current-carrying conductors
- AC circuit with L, C, R — resonance condition and Q-factor
- Lens maker's equation
- Einstein's photoelectric equation
- Expression for de Broglie wavelength
Important Numericals (Practice These First)
- Coulomb's law and superposition principle
- Electric potential and work done moving a charge
- Kirchhoff's laws and Wheatstone bridge
- Moving coil galvanometer: conversion to ammeter/voltmeter
- Transformer problems (efficiency, turns ratio, power loss)
- Refraction through prism (angle of deviation, minimum deviation)
- Mirror and lens formula + magnification
- Radioactive decay and half-life calculations
How to Write Physics Answers in Board Exams
- 1Start every derivation by stating what you want to prove.
- 2Draw a labelled diagram — even if not asked, it earns presentation marks.
- 3Write the formula first, then substitute values with units.
- 4For 3-mark questions: definition + formula + example OR 3 points.
- 5For 5-mark questions: use headings, step numbering, and a concluding statement.
- 6Never skip units in numerical answers — this is a common 1-mark loss.
30-Day Revision Plan
- Days 1–10: Revise all derivations and formulae chapter by chapter
- Days 11–20: Solve 2 previous year papers and analyse weak areas
- Days 21–25: Target weak chapters with focused numerical practice
- Days 26–29: Full syllabus formula sheet revision
- Day 30: Rest, light revision only
"Physics is not about memorising facts. It's about understanding the story behind each formula — where it comes from, and when to use it."