CBSE Class 12 Physics. Derivations, numericals, full marks.
Physics is the subject most Class 12 PCM students fear — and the one most likely to pull down the aggregate. It doesn't have to. Here's the chapter-by-chapter priority, the derivation list, and the numerical strategy that turns Physics into a scoring subject.
CBSE Class 12 Physics — chapter priorities, derivations, and board exam strategy
The chapters that carry CBSE Class 12 Physics
Electrostatics and Current Electricity together carry 16 marks every year — the single highest-weight unit. Magnetic Effects of Current and Magnetism carry another 17 marks. These two units alone account for 33 of 70 theory marks. Start here.
Electromagnetic Induction and Alternating Current (17 marks), Optics (18 marks), and Dual Nature + Atoms + Nuclei + Semiconductors (collectively 15 marks) cover the remaining theory. Electronic Devices (Semiconductors) is a short chapter worth 7 marks and fully predictable.
Derivations — the marks no one should lose
CBSE Class 12 Physics has approximately 25 derivations that have appeared in board papers across 10 years. Of these, 8–10 appear in almost every paper: Gauss's Law (electric flux), Biot-Savart Law, Ampere's Circuital Law, Faraday's Law, lens formula, mirror formula, Bohr's model energy levels, and semiconductor junction derivations.
Each derivation carries 3–5 marks and the CBSE marking scheme allocates marks to each step. A student who has written each derivation 5 times from memory answers faster and scores higher than one who understands it conceptually but hasn't written it out.
Numericals — method first, answer second
CBSE awards step marks for numericals. Writing the formula first, substituting values clearly, and showing units at each step earns marks even when the arithmetic goes wrong. The habit of writing complete working must be built during practice.
High-frequency numerical topics: Coulomb's Law and electric field calculations, current and resistance (Kirchhoff's laws, Wheatstone bridge), magnetic force on moving charges, lens and mirror numerical, photoelectric effect, and nuclear decay. These appear in every paper — practice them until the method is automatic.
Diagrams — easy marks most students skip
Physics diagrams are worth 1–2 marks each and are among the easiest marks in the paper. The required diagrams are predictable: electric field lines for different charge configurations, circuit diagrams for Wheatstone bridge and potentiometer, ray diagrams for refraction and total internal reflection, and energy band diagrams for semiconductors.
Practise drawing each diagram with labels at least 3 times. CBSE's marking scheme deducts marks for missing labels — not for artistic quality. A neat, labelled diagram earns full marks.
Starting in August — the Physics preparation timeline
August: Electric Charges and Fields, Electrostatic Potential and Capacitance (Chapters 1–2). September: Current Electricity, Moving Charges and Magnetism (Chapters 3–4). October: Electromagnetic Induction, Alternating Current (Chapters 6–7). November: Optics — Ray and Wave (Chapters 9–10). December onwards: Dual Nature, Atoms, Nuclei, Semiconductors + full paper practice.
One chapter every 2 weeks from August gives you comfortable coverage by November, with December and January for revision, full papers, and derivation drilling.
Ready to get started? Try ClearSteps free for 14 days.
Start my 14-day free trialThree tools used every day till the boards
Drills the chapters that matter
Questions weighted to the real CBSE exam pattern — not last year's book. Practise what actually shows up in the paper.
Build a fresh test in 30 seconds
Pick subject, chapters, marks, difficulty. An exam-style timed paper ready to go. Unlimited.
Every PYQ, decoded
Previous year papers 2015–2025, all subjects, with official marking schemes and an AI pattern read.
Frequently asked questions
Which chapters are most important for CBSE Class 12 Physics?
Electrostatics (Chapter 1–2), Current Electricity (Chapter 3), Magnetic Effects (Chapter 4–5), Optics (Chapters 9–10), and Semiconductor Electronics (Chapter 14) together carry 55–60 of the 70 theory marks. Electromagnetic Induction and AC Circuits (Chapters 6–7) are also high-weight. These chapters should get 70% of your preparation time.
How many derivations are important for CBSE Class 12 Physics?
Approximately 20–25 derivations appear across 10 years of CBSE Class 12 Physics papers. Of these, 8–10 are near-certain: Gauss's Law, Biot-Savart Law, Ampere's Law, Faraday's Law, lens maker's equation, mirror formula, Bohr's model, and semiconductor p-n junction equations. Learn these first.
How to score 90+ in CBSE Class 12 Physics?
Master the 10 high-frequency derivations. Practise numericals chapter-by-chapter with complete step-wise working. Solve 5 full previous year Physics papers under 3-hour conditions. Check every answer against the official CBSE marking scheme. Practise all required diagrams with labels. Scores above 90 come from not losing step marks — that requires consistent practice, not last-minute cramming.
Is Physics hard in CBSE Class 12?
Physics has a large syllabus with both conceptual derivations and numerical application — that combination makes it challenging. But the CBSE paper pattern is highly predictable: the same chapters, the same derivation types, the same numerical formats appear every year. Students who practise with previous year papers and marking schemes find the exam much more manageable than students who study from textbooks alone.
How to prepare for Class 12 Physics in 6 months?
Chapters 1–5 (Electrostatics, Current Electricity, Magnetic Effects) in months 1–2. Chapters 6–10 (EMI, AC, EM Waves, Optics) in months 3–4. Chapters 11–14 (Dual Nature, Atoms, Nuclei, Semiconductors) in month 5. Full paper practice and derivation revision in month 6.
Related guides
Class 12 Physics — from fear to full marks.
Chapter weights, derivation list, PYQ analysis, AI question bank. 14 days free, no card needed.
No card needed · Activate on WhatsApp in 30 seconds