Class 12 Physics Notes

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Class 12 Physics Notes

One place for all your Class 12 Physics revision. Chapter-wise notes covering electric charges and fields, electrostatic potential, current electricity, magnetism, electromagnetic induction, alternating current, ray and wave optics, and modern physics — atoms, nuclei, the photoelectric effect and semiconductors — each with key formulas, exam pointers and solved JEE/NEET examples.

Class:12Subject:PhysicsCovers:CBSE · JEE · NEET

9 Key Formulas

DWritten byDeep Narayan

UpdatedSeptember 2026

Key Concept Summary

What is covered in Class 12 Physics?

Class 12 Physics spans electrostatics (electric charges, potential and capacitance), current electricity, magnetism and electromagnetic induction, alternating current, ray and wave optics, and modern physics — the core of the CBSE syllabus and a major part of JEE Main and NEET.

About the Class 12 Physics Notes

These chapter-wise notes condense the entire Class 12 physics syllabus into quick-revision sheets. Each chapter page gives you the essential concepts, the key formulas together, exam pointers for the exam hall, and a quick FAQ answering the most-asked questions.

How to use these notes

Use each chapter page for last-minute revision: read the quick answer, scan the key formulas, then test yourself with the exam pointers. The formula sections double as a revision sheet right before the exam.

Electrostatics

Electric Charges and Fields — Coulomb's law, electric field, Gauss's law and the dipole.
Electrostatic Potential and Capacitance — potential, capacitors, dielectrics and energy stored.

Coulomb's law and potential

F = k \frac{q _{1} q _{2}}{r ^{2}}, V = \frac{1}{4 π ε _{0}} \frac{Q}{r}

Current Electricity and Magnetism

Current Electricity — Ohm's law, Kirchhoff's laws, Wheatstone bridge and the potentiometer.
Moving Charges and Magnetism — Lorentz force, Biot-Savart law and the cyclotron.
Magnetism and Matter — bar magnets, dia/para/ferro magnetism and Earth's field.

Ohm's law and Lorentz force

V = I R, F = q (v \times B)

Induction, AC and Optics

Electromagnetic Induction — Faraday's law, Lenz's law, inductors and transformers.
Alternating Current — RMS values, LCR circuits, resonance and power factor.
Ray Optics and Optical Instruments — mirrors, lenses, prisms, microscopes and telescopes.
Wave Optics — Huygens' principle, interference, Young's double-slit experiment, diffraction and polarisation.

Faraday's law, LC resonance and fringe width

ε = - \frac{d Φ}{d t}, ω_{0} = \frac{1}{L C}, β = \frac{λ D}{d}

Modern Physics and Semiconductor Electronics

Electromagnetic Waves — displacement current, Maxwell's equations and the electromagnetic spectrum.
Atoms — Bohr's model, energy levels and spectral lines of hydrogen.
Dual Nature of Radiation and Matter — the photoelectric effect and de Broglie waves.
Nuclei — mass defect, binding energy, radioactivity and fission/fusion.
Semiconductor Electronics — p-n junctions, diodes, rectifiers, transistors and logic gates.

Modern physics and radioactivity

E = h ν = \frac{h c}{λ}, λ = \frac{h}{p}, N = N_{0} e^{- λ t}

Modern physics is high-yield

The photoelectric effect, Bohr's atom, binding energy and semiconductor devices produce frequent, formula-driven questions in boards, JEE and NEET — every one now has a dedicated chapter page linked from this hub.

Quick Revision

Key formulas at a glance

Memorise these equations — direct application numericals and derivations in CBSE & JEE frequently hinge on these.

Coulomb's law

F = k \frac{q _{1} q _{2}}{r ^{2}}

Potential (point charge)

V = \frac{1}{4 π ε _{0}} \frac{Q}{r}

Faraday's law

ε = - \frac{d Φ}{d t}

Lorentz force

F = q (v \times B)

LCR resonance

ω_{0} = \frac{1}{L C}

Lens maker formula

\frac{1}{f} = (n - 1) (\frac{1}{R _{1}} - \frac{1}{R _{2}})

Photon energy

E = h ν = \frac{h c}{λ}

de Broglie wavelength

λ = \frac{h}{p}

Decay law

N = N_{0} e^{- λ t}

Exam Strategy

How this chapter is asked

High-yield question patterns observed across CBSE boards, JEE Main & Advanced, and NEET.

Electric field: Gauss's law Φ_E = q_enc/ε₀.
Capacitance of a parallel plate C = κε₀A/d.
Faraday's law ε = −dΦ/dt; Lenz's law opposes flux change.
LCR resonance at ω₀ = 1/√LC.
Lens maker: 1/f = (n−1)(1/R₁ − 1/R₂).

FAQ

Frequently asked questions

How many chapters are there in Class 12 Physics?

The CBSE Class 12 physics syllabus contains about 10–14 chapters spanning electrostatics, current electricity, magnetism, electromagnetic induction, AC, optics and modern physics. This hub links each chapter's dedicated revision notes.

Which Class 12 physics chapters are most important for JEE and NEET?

Electrostatics and current electricity, magnetism and electromagnetic induction are heavily weighted. Ray optics and modern physics also contribute steady marks and are often easier to score in boards.

What is the hardest topic in Class 12 physics?

Many students find electromagnetic induction and LCR alternating-current circuits the most demanding. Break them into small steps and practise the key formulas — Faraday's law and resonance.

How should I revise Class 12 physics?

Practise the core formulas (Coulomb's law, Ohm's law, Faraday's law, resonance, lens maker) then solve numericals using each chapter's key-formulas section as a quick revision sheet before the exam.

Next Chapters

Continue learning

Class 12 Physics Notes in Hindi Electric Charges and Fields Notes Electrostatic Potential and Capacitance Notes Current Electricity Notes Moving Charges and Magnetism Notes Magnetism and Matter Notes Electromagnetic Induction Notes Alternating Current Notes Ray Optics and Optical Instruments Notes Wave Optics Notes Electromagnetic Waves Notes Atoms Notes Dual Nature of Radiation and Matter Notes Nuclei Notes Semiconductor Electronics Notes Class 12 Chemistry Notes Physics Tutor in Mohali Class 12 Physics NCERT Solutions

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