CBSE Class 12 Physics: chapter-wise important topics

The derivations, numericals and concepts that come up most often in CBSE Class 12 Physics, chapter by chapter, and how to revise them for boards.

Paper Predict Notes · 21 Jul 2026

CBSE Class 12 Physics is a paper where preparation pays off clearly. The syllabus is fixed, the derivations that can be asked are limited, and the numericals follow familiar patterns. Most students who lose marks do so not because the paper was unfair, but because they skipped a derivation, mixed up a formula, or ran out of time.

The theory paper is worth 70 marks, with 30 marks for practicals. This guide goes chapter by chapter through the topics that come up most often, so you can prioritise your revision.

How the Class 12 Physics paper is structured

The paper usually mixes several types of question.

• Multiple choice and assertion-reason questions that test concepts quickly.
• Short answer questions that ask for a definition, a reason or a short derivation.
• Case-based questions built around a short passage or situation.
• Long answer questions that usually include a derivation or a multi-step numerical.

Check the latest CBSE sample paper and marking scheme for your year before your final revision. They show the exact structure and how marks are given.

Electrostatics

Electric Charges and Fields

• Coulomb's law and the principle of superposition.
• Electric field due to a dipole on the axial and equatorial lines.
• Torque on a dipole in a uniform field.
• Gauss's law and its applications: infinite line charge, infinite plane sheet and thin spherical shell.

Electrostatic Potential and Capacitance

• Potential due to a point charge and a dipole.
• Equipotential surfaces and their properties.
• Capacitance of a parallel plate capacitor, with and without a dielectric.
• Energy stored in a capacitor, and series and parallel combinations.

Gauss's law applications and the parallel plate capacitor are among the most frequently asked derivations in the whole paper.

Current Electricity

• Drift velocity and its relation to current.
• Ohm's law, resistivity and its temperature dependence.
• Kirchhoff's laws and the Wheatstone bridge.
• EMF, internal resistance and combinations of cells.

Numericals using Kirchhoff's laws come up regularly. Practise drawing clean circuit diagrams with current directions marked.

Magnetic Effects of Current and Magnetism

Moving Charges and Magnetism

• Biot-Savart law and the field on the axis of a circular loop.
• Ampere's circuital law and its application to a long straight wire and a solenoid.
• Force on a moving charge and on a current-carrying conductor.
• Torque on a current loop, and the moving coil galvanometer.

Magnetism and Matter

• The bar magnet as an equivalent solenoid.
• Magnetic properties of materials: dia-, para- and ferromagnetism.

Electromagnetic Induction and Alternating Current

Electromagnetic Induction

• Faraday's laws and Lenz's law.
• Motional EMF.
• Self-inductance and mutual inductance.

Alternating Current

• Reactance and impedance in LCR circuits.
• Resonance and the quality factor.
• Power in AC circuits and the power factor.
• The transformer: principle, working and energy losses.

The LCR circuit and the transformer are frequent long-answer topics.

Electromagnetic Waves

• Displacement current.
• Characteristics of electromagnetic waves.
• The electromagnetic spectrum and the uses of each region.

This chapter is short and mostly factual, so it is quick to secure.

Optics

Ray Optics and Optical Instruments

• Mirror formula and lens maker's formula.
• Refraction at a spherical surface.
• Total internal reflection and its applications.
• Refraction through a prism.
• The compound microscope and the astronomical telescope, with ray diagrams.

Wave Optics

• Huygens' principle and the laws of reflection and refraction using wavefronts.
• Young's double slit experiment and fringe width.
• Diffraction at a single slit.
• Polarisation and Brewster's law.

Ray diagrams for optical instruments must be neat and correctly labelled. They are easy marks if practised, and easy to lose if rushed.

Modern Physics

Dual Nature of Radiation and Matter

• The photoelectric effect and Einstein's equation.
• Experimental observations of the photoelectric effect.
• De Broglie wavelength.

Atoms and Nuclei

• Bohr's model and the energy levels of hydrogen.
• The hydrogen spectrum.
• Mass defect and binding energy, and the binding energy curve.
• Nuclear fission and fusion.

Semiconductor Electronics

• Intrinsic and extrinsic semiconductors.
• The p-n junction and its forward and reverse bias characteristics.
• The diode as a rectifier.

Modern Physics chapters are relatively short and scoring. Many questions are direct applications of a formula or a graph.

How to revise Class 12 Physics for boards

1. Make a derivation list. Write every derivation in the syllabus on one sheet. Practise writing each one from memory until you can do it without looking.
2. Keep a formula sheet per chapter. Include units and the meaning of each symbol.
3. Practise numericals in sets. Do ten questions from one chapter, then a mixed set from several chapters.
4. Draw diagrams every time. Circuit diagrams, ray diagrams and graphs earn marks and make answers clearer.
5. Solve previous year papers under time. This builds speed and shows which question types repeat.

Answer-writing tips

• Start derivations with a labelled diagram. It shows the examiner you know the setup.
• Write the formula before substituting values. Marks are often given for the formula alone.
• Always write units. Missing units can cost marks in numericals.
• Underline the final answer so the examiner can find it quickly.

Frequently asked questions

Which chapters are most important in Class 12 Physics?

Electrostatics, Current Electricity, Magnetic Effects of Current, Electromagnetic Induction and AC, Optics and Modern Physics together cover the paper. Optics and Electrostatics usually carry the most marks.

How many derivations should I prepare?

Prepare every derivation listed in the current syllabus. The list is finite, and derivations are among the most reliable questions in the paper.

Is NCERT enough for Class 12 Physics boards?

NCERT covers the content. Add the NCERT exemplar and previous year papers for practice.

The short version

Class 12 Physics is predictable if you prepare systematically. List every derivation and practise writing them, keep a formula sheet per chapter, practise numericals in mixed sets, draw diagrams in every answer, and solve previous year papers under timed conditions.

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