Class 12 Physics is the most feared CBSE board subject. The syllabus is large, derivations are long, and the marking is unforgiving. But if you study strategically, a majority of the marks come from a handful of topics that appear in some form every single year.
Unit-Wise Marks Breakdown
| Unit | Topics Covered | Marks |
|---|---|---|
| Unit I | Electric Charges & Fields, Electrostatic Potential | 8 |
| Unit II | Current Electricity | 7 |
| Unit III | Magnetic Effects of Current & Magnetism | 8 |
| Unit IV | Electromagnetic Induction & AC | 8 |
| Unit V | Electromagnetic Waves | 3 |
| Unit VI | Optics | 14 |
| Unit VII | Dual Nature of Radiation | 4 |
| Unit VIII | Atoms & Nuclei | 6 |
| Unit IX | Electronic Devices (Semiconductors) | 7 |
Tip
Optics alone carries 14 marks — more than any other unit. Master all ray diagram types (concave/convex mirrors and lenses) and the key derivations here. Every hour spent on Optics has the highest marks-per-hour return in the entire syllabus.
Topics That Have Appeared Every Year (2015–2024 Analysis)
- 1.Derivation of electric field using Gauss's Law — Electric Charges chapter
- 2.Ohm's Law, resistivity, and drift velocity — Current Electricity
- 3.Biot-Savart Law and its application to a circular loop — Magnetism
- 4.Faraday's Laws of Electromagnetic Induction — EMI chapter
- 5.Mirror formula and lens formula with ray diagram and numerical — Optics
- 6.Photoelectric effect — Einstein's equation and graph interpretation
- 7.Truth tables for AND, OR, NOT, NAND, NOR logic gates — Semiconductors
High-Value Derivations to Master First
CBSE regularly asks 5-mark derivation questions. These are fully predictable — the same derivations appear year after year. Mastering the following will guarantee 15–20 derivation marks in the exam:
- Electric potential energy of a system of charges
- Expression for torque on a current-carrying loop in a magnetic field
- Derivation of mirror formula
- Derivation of lens maker's equation
- Einstein's photoelectric equation
- Expression for de Broglie wavelength
How to Approach Physics Numericals
Physics numericals follow a strict format that CBSE examiners expect. Always: (1) list the given values, (2) write the formula, (3) substitute and solve step by step, (4) write the final answer with correct units. Examiners award step marks — a wrong final answer with correct steps and formula still earns 3 out of 5.
The 6-Week CBSE Physics Preparation Plan
- 1.Week 1–2: Complete Optics and Electricity with all key derivations
- 2.Week 3: Complete Magnetism, EMI, and Modern Physics
- 3.Week 4: First full mock paper — review every wrong answer thoroughly
- 4.Week 5: Second mock paper — focus revision on weak chapters only
- 5.Week 6: Revise all derivations and diagrams from memory. No new topics.