By NCERT Kaksha Team · Last updated: 15 July 2026 · Reading time: 8 min · Bookmark this page 🔖
Quick Answer
CBSE Class 12 Physics (2026) has 14 chapters across 9 units, and roughly 150 core formulas decide almost every numerical in the 70-mark paper. This page lists the key formulas of all 14 chapters in tables — from Coulomb's law to logic gates — with the exam use of each. Highest-payoff chapters by weightage: Optics (unit: 18 marks), Magnetism + EMI/AC (17), and Electrostatics + Current Electricity (16).
Where the marks live: 2026 unit weightage
Before memorising anything, know the payoff. CBSE's official 2026 blueprint distributes the 70 theory marks like this — and formulas from the top three rows power more than 70% of the paper's numericals:
| Units (chapters) |
Marks |
| Electrostatics + Current Electricity (Ch 1–3) |
16 |
| Magnetic Effects + Magnetism, EMI + AC (Ch 4–7) |
17 |
| EM Waves + Optics (Ch 8–10) |
18 |
| Dual Nature + Atoms & Nuclei (Ch 11–13) |
12 |
| Electronic Devices (Ch 14) |
7 |
Ch 1 — Electric Charges & Fields 16-mark unit
| Formula |
Used for |
| F = kq₁q₂/r² |
Coulomb's law; k = 1/4πε₀ = 9 × 10⁹ N·m²/C² |
| E = F/q₀ = kQ/r² |
Electric field of a point charge |
| p = q × 2a |
Dipole moment (charge × separation) |
| E(axial) = 2kp/r³ |
Field on dipole axis (r ≫ a) |
| E(equatorial) = kp/r³ |
Field on perpendicular bisector — half the axial value |
| τ = pE sinθ |
Torque on a dipole in a uniform field |
| Φ = q(enclosed)/ε₀ |
Gauss's theorem — the unit's favourite derivation source |
| E = λ/2πε₀r |
Infinite straight charged wire |
| E = σ/2ε₀ |
Infinite plane sheet (independent of distance!) |
| E = kQ/r² (outside), 0 (inside) |
Charged spherical shell |
Ch 2 — Electrostatic Potential & Capacitance 16-mark unit
| Formula |
Used for |
| V = kq/r |
Potential of a point charge (scalar — just add for systems) |
| V = kp cosθ/r² |
Dipole potential; zero on the equatorial line |
| U = kq₁q₂/r |
Potential energy of a two-charge system |
| E = −dV/dr |
Field–potential relation; E points from high V to low V |
| C = Q/V; C = ε₀A/d |
Capacitance; parallel-plate capacitor |
| C′ = KC |
Dielectric (constant K) multiplies capacitance |
| Series: 1/C = 1/C₁ + 1/C₂; Parallel: C = C₁ + C₂ |
Combinations — opposite of resistors! |
| U = ½CV² = Q²/2C = ½QV |
Energy stored — pick the form matching given data |
| u = ½ε₀E² |
Energy density of an electric field |
Ch 3 — Current Electricity 16-mark unit
| Formula |
Used for |
| I = Q/t = neAv𝒹 |
Current; drift-velocity form for conductor numericals |
| V = IR; R = ρl/A |
Ohm's law; resistance from dimensions |
| ρ = m/(ne²τ) |
Resistivity from relaxation time τ |
| R_T = R₀(1 + αΔT) |
Temperature dependence of resistance |
| P = VI = I²R = V²/R |
Electrical power — I²R for series, V²/R for parallel |
| ε = V + Ir; V = ε − Ir |
EMF vs terminal voltage of a cell |
| ΣI = 0; ΣV = 0 |
Kirchhoff's junction and loop rules |
| P/Q = R/S |
Wheatstone bridge balance condition |
Ch 4 — Moving Charges & Magnetism 17-mark unit
| Formula |
Used for |
| F = qvB sinθ |
Lorentz force on a moving charge |
| r = mv/qB |
Radius of circular motion in a field — classic 3-marker |
| F = BIl sinθ |
Force on a current-carrying conductor |
| dB = (μ₀/4π) · I dl sinθ/r² |
Biot–Savart law |
| B = μ₀NI/2r |
Field at centre of a circular coil |
| B = μ₀nI |
Inside a long solenoid (n = turns/length) |
| F/l = μ₀I₁I₂/2πd |
Force per length between parallel wires — defines the ampere |
| τ = NIAB sinθ = mB sinθ |
Torque on a current loop; m = NIA |
Ch 5 — Magnetism & Matter 17-mark unit
| Formula |
Used for |
| B(axial) = μ₀2m/4πr³ |
Bar magnet's axial field — mirror of the electric dipole |
| B(equatorial) = μ₀m/4πr³ |
Equatorial field, half the axial value |
| τ = mB sinθ; U = −mB cosθ |
Torque and energy of a magnet in a field |
| χ = M/H; μᵣ = 1 + χ |
Susceptibility; classify dia/para/ferro materials |
| B = μ₀(H + M) |
Field inside a magnetized material |
Ch 6 — Electromagnetic Induction 17-mark unit
| Formula |
Used for |
| Φ = BA cosθ |
Magnetic flux through a coil |
| ε = −N dΦ/dt |
Faraday's law; minus sign = Lenz's law |
| ε = Blv |
Motional EMF of a rod — most repeated numerical |
| ε = −L dI/dt; L = μ₀n²Al |
Self-inductance; solenoid value |
| ε₂ = −M dI₁/dt |
Mutual inductance |
| U = ½LI² |
Energy stored in an inductor |
Ch 7 — Alternating Current 17-mark unit
| Formula |
Used for |
| I(rms) = I₀/√2; V(rms) = V₀/√2 |
RMS values — what meters read |
| X_L = ωL; X_C = 1/ωC |
Inductive and capacitive reactance |
| Z = √(R² + (X_L − X_C)²) |
Impedance of a series LCR circuit |
| ω₀ = 1/√(LC) |
Resonant frequency — Z minimum, current maximum |
| P = V(rms)I(rms) cosφ; cosφ = R/Z |
Average power; power factor |
| V_s/V_p = N_s/N_p = I_p/I_s |
Ideal transformer relations |
Ch 8 — Electromagnetic Waves 18-mark unit
| Formula |
Used for |
| c = 1/√(μ₀ε₀) |
Speed of light from field constants |
| c = E₀/B₀ |
Ratio of field amplitudes in the wave |
| E = hν = hc/λ |
Photon energy — bridges into Ch 11 |
Ch 9 — Ray Optics 18-mark unit
| Formula |
Used for |
| 1/f = 1/v + 1/u |
Mirror formula (with sign convention!) |
| m = −v/u = h′/h |
Magnification, mirrors and lenses |
| n₁ sinθ₁ = n₂ sinθ₂ |
Snell's law of refraction |
| sin C = 1/n |
Critical angle → total internal reflection |
| 1/f = 1/v − 1/u |
Thin lens formula |
| 1/f = (n − 1)(1/R₁ − 1/R₂) |
Lens maker's formula — top-3 derivation ask |
| P = 1/f(in m); P = P₁ + P₂ |
Power in dioptre; lenses in contact |
| n = sin((A + D_m)/2) / sin(A/2) |
Prism — refractive index from minimum deviation |
| m = (L/f₀)(D/f_e) |
Compound microscope magnification |
| m = f₀/f_e |
Astronomical telescope (normal adjustment) |
Ch 10 — Wave Optics 18-mark unit
| Formula |
Used for |
| β = λD/d |
Fringe width in Young's double slit — the chapter's #1 numerical |
| d sinθ = nλ / (n + ½)λ |
Conditions for bright / dark fringes |
| I = 4I₀cos²(φ/2) |
Intensity in interference pattern |
| a sinθ = nλ |
Single-slit diffraction minima |
| tanθ_p = n |
Brewster's law — polarisation by reflection |
| I = I₀cos²θ |
Malus's law for polaroids |
Ch 11 — Dual Nature of Radiation & Matter 12-mark unit
| Formula |
Used for |
| hν = φ₀ + KE(max) |
Einstein's photoelectric equation — guaranteed question territory |
| KE(max) = eV₀ |
Stopping potential relation |
| λ = h/p = h/mv |
de Broglie wavelength |
| λ = h/√(2meV) ≈ 12.27/√V Å |
Electron accelerated through V volts |
Ch 12 — Atoms 12-mark unit
| Formula |
Used for |
| rₙ = 0.529 n²/Z Å |
Bohr orbit radius |
| Eₙ = −13.6 Z²/n² eV |
Energy levels of hydrogen-like atoms |
| 1/λ = R(1/n₁² − 1/n₂²) |
Rydberg formula — spectral series numericals |
| mvr = nh/2π |
Bohr's quantisation of angular momentum |
Ch 13 — Nuclei 12-mark unit
| Formula |
Used for |
| R = R₀A^⅓ |
Nuclear radius (R₀ ≈ 1.2 fm) → constant nuclear density |
| E = Δmc² |
Mass–energy equivalence |
| BE = Δm × 931.5 MeV |
Binding energy with mass defect in u |
| BE/A curve |
Explains fission (heavy) and fusion (light) energy release |
Ch 14 — Semiconductor Electronics 7-mark unit
| Formula / relation |
Used for |
| nₑn_h = nᵢ² |
Carrier concentrations in doped semiconductors |
| Diode: forward ON, reverse OFF |
Rectifier circuits — half wave (1 diode), full wave (2) |
| Gates: AND (A·B), OR (A+B), NOT (Ā), NAND, NOR |
Truth-table questions — nearly free marks every year |
How to revise ~150 formulas without forgetting
Don't memorise the list top to bottom — memorise it by symmetry. Class 12 physics is built on repeated patterns: the electric dipole (2kp/r³ axial, kp/r³ equatorial) and the bar magnet (μ₀2m/4πr³, μ₀m/4πr³) are the same mathematics; capacitor combinations are resistor combinations inverted; X_L = ωL and X_C = 1/ωC mirror each other. Learning 8 patterns is easier than learning 150 independent lines.
Then apply the 3-pass rule: write each chapter's formulas from memory once a week (writing beats reading for recall), check against this page, and re-write only the ones you missed. Most students hold the full set comfortably within 3 weeks of this cycle — and every formula written from memory during revision is one your hand already knows in the exam hall.
💡 Sign conventions score more than formulas
In Ray Optics, more marks are lost to wrong signs of u, v, f than to forgotten formulas. Fix one convention (new Cartesian: distances measured from pole, direction of incident light positive) and apply it in writing in every numerical — examiners award the substitution step only if signs are right.
The complete handwritten formula sheet — all chapters, 26 pages, zero bakwaas
This page covers the core ~150 formulas. Our Class 12 Physics Formula Sheet is the version toppers stick on the wall for the last 30 days:
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Compact 26 pages — the full 2026-27 CBSE syllabus, every chapter, nothing extra
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Colour-coded formula boxes, derivations and diagrams for fast recall
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Real handwritten notes by toppers — IITians, NITians and district toppers
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Instant PDF or printed book (COD available, all-India 3–5 day delivery)
- Rated 4.6★ by 680+ verified students
Get the Formula Sheet →
FAQs
How many formulas are there in Class 12 Physics?
Around 150 core formulas across the 14 chapters decide almost all numericals, with Optics, Electrostatics, Current Electricity and EMI/AC contributing the largest share.
Which chapters have the most formulas in Class 12 Physics?
Ray Optics, Current Electricity, Moving Charges & Magnetism, and Alternating Current are the most formula-dense. Semiconductors and EM Waves are the lightest.
Which chapter has the highest weightage in CBSE Physics 2026?
The Optics unit (Ray + Wave Optics with EM Waves) carries 18 marks — the highest — followed by the Magnetism + EMI/AC block at 17 and Electrostatics + Current Electricity at 16.
Are formulas enough to solve Class 12 Physics numericals?
Formulas plus three more things: correct sign conventions, SI unit conversion before substitution, and recognising which formula the given data points to. That recognition comes from solving previous-year numericals.
Is there a formula sheet for Class 12 Physics in Hindi?
The formulas themselves are universal symbols — this page works for Hindi-medium students directly, and handwritten formula sheets with bilingual annotations make the terms easier to connect.
How should I revise physics formulas before the board exam?
Weekly write-from-memory passes per chapter, re-writing only missed formulas, and learning paired patterns (dipole–magnet, capacitor–resistor, X_L–X_C) instead of isolated lines.
Do I need to remember derivations or just formulas?
Both, selectively: CBSE repeatedly asks derivations of Gauss-law applications, lens maker's formula, mirror formula, motional EMF and the LCR impedance — learn those step-by-step; for the rest, the final formula usually suffices.
Can I get all these formulas as a PDF?
Bookmark this page for the online version — and the complete handwritten formula sheet (linked above) is available as an instant-download PDF or printed book covering the full syllabus with diagrams and sign conventions.
