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Complete Class 12 Physics Formulas – All Chapters

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Complete Class 12 Physics Formulas – Physics is one of the most important subjects in senior secondary education because it builds a strong base for engineering, medical, and other science careers. To score well in board exams and competitive exams, students must have a clear understanding of concepts along with proper revision of formulas. This Complete Class 12 Physics Formulas – All Chapters guide is carefully prepared to help students revise quickly and effectively. It works as a reliable formula sheet for physics class 12 covering all major topics such as Electrostatics, Current Electricity, Magnetism, Optics, Modern Physics, and more.

This well-organized physics formula sheet class 12 and class 12 physics formula sheet includes chapter-wise equations, key derivations, SI units, symbols, and important constants. Students can also use this resource as a physics class 12 formula sheet pdf for last-minute revision before exams. Many learners search for physics formulas for class 12 pdf download and class 12 physics important formulas to save time during preparation, and this guide aims to meet that need in a simple and structured format.

All formulas are verified according to the latest syllabus and exam pattern, so students can trust the accuracy. However, it is always better to understand the logic behind formulas instead of only memorizing them, because sometimes small conceptual mistakes can lead to wrong answers.

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Complete Class 12 Physics Formulas – All Chapters

CBSE Class 12 Physics Formulas Chapters wise

1. Electrostatics

Concept Formula Description SI Unit
Coulomb’s Law F = kq₁q₂/r² Force between two point charges; k = 9×10⁹ N·m²/C² Newton (N)
Electric Field E = F/q = kQ/r² Force per unit positive test charge N/C or V/m
Electric Potential V = kQ/r Work done per unit charge Volt (V)
Potential Energy U = kq₁q₂/r Energy of system of two charges Joule (J)
Electric Flux Φ = E·A·cosθ Total field lines through a surface N·m²/C
Gauss’s Law Φ = q_enc/ε₀ Net flux = enclosed charge / ε₀ N·m²/C
Capacitance C = Q/V Charge stored per unit voltage Farad (F)
Parallel Plate Cap. C = ε₀A/d A = area, d = separation Farad (F)
Energy in Capacitor U = ½CV² = Q²/2C Electrostatic energy stored Joule (J)
Capacitors in Series 1/C = 1/C₁+1/C₂+… Equivalent capacitance (series) Farad (F)
Capacitors Parallel C = C₁+C₂+… Equivalent capacitance (parallel) Farad (F)
Dielectric Effect C’ = KC = Kε₀A/d K = dielectric constant Farad (F)

2. Current Electricity

Concept Formula Description SI Unit
Ohm’s Law V = IR Voltage = Current × Resistance Volt (V)
Resistance R = ρL/A ρ = resistivity, L = length, A = area Ohm (Ω)
Resistors Series R = R₁+R₂+… Series combination Ohm (Ω)
Resistors Parallel 1/R = 1/R₁+1/R₂+… Parallel combination Ohm (Ω)
Electric Power P = VI = I²R = V²/R Rate of energy dissipation Watt (W)
Electric Energy E = Pt = VIt Energy consumed Joule (J)
Current Density J = I/A = σE σ = conductivity A/m²
Drift Velocity vd = I/(nAe) n = number density of electrons m/s
EMF & Int. Resistance V = E – Ir E = EMF, r = internal resistance Volt (V)
Kirchhoff’s Voltage ΣV = 0 (closed loop) Sum of potentials in any loop = 0 Volt (V)
Kirchhoff’s Current ΣI = 0 (junction) Sum of currents at junction = 0 Ampere (A)
Wheatstone Bridge P/Q = R/S Balance condition Dimensionless

3. Magnetic Effects of Current

Concept Formula Description SI Unit
Biot–Savart Law dB = μ₀Idlsinθ/4πr² Magnetic field due to current element Tesla (T)
Field Due to Wire B = μ₀I/2πr Long straight current-carrying wire Tesla (T)
Field at Centre (Circle) B = μ₀I/2r Centre of circular current loop Tesla (T)
Ampere’s Law ∮B·dl = μ₀I Relates B to enclosed current Tesla·m
Solenoid Field B = μ₀nI n = turns per unit length Tesla (T)
Toroid Field B = μ₀NI/2πr N = total turns Tesla (T)
Lorentz Force F = q(v×B) Force on moving charge in B-field Newton (N)
Force on Wire F = BILsinθ L = length, θ = angle with B Newton (N)
Torque on Loop τ = NIAB sinθ N turns, area A in field B N·m
Magnetic Moment M = NIA Of a current-carrying loop A·m²
Cyclotron Frequency f = qB/2πm Frequency of circular motion Hertz (Hz)
Radius (Cyclotron) r = mv/qB Radius of circular path Meter (m)

4. Electromagnetic Induction

Concept Formula Description SI Unit
Magnetic Flux Φ = BAcosθ Flux through area A Weber (Wb)
Faraday’s Law EMF = -dΦ/dt Induced EMF = rate of change of flux Volt (V)
Lenz’s Law Opposes cause Induced current opposes change in flux —
Motional EMF EMF = BLv Rod moving with velocity v Volt (V)
Self-Inductance EMF = -L(dI/dt) L = self-inductance Henry (H)
Mutual Inductance EMF = -M(dI/dt) M = mutual inductance Henry (H)
Energy in Inductor U = ½LI² Energy stored in inductor Joule (J)
Transformers Vs/Vp = Ns/Np Ideal transformer ratio Dimensionless

5. Alternating Current (AC)

Concept Formula Description SI Unit
RMS Voltage Vrms = V₀/√2 Root mean square value Volt (V)
RMS Current Irms = I₀/√2 Root mean square current Ampere (A)
Inductive Reactance XL = ωL = 2πfL Opposition by inductor Ohm (Ω)
Capacitive Reactance XC = 1/ωC Opposition by capacitor Ohm (Ω)
Impedance (RLC) Z = √(R²+(XL-XC)²) Total opposition to AC Ohm (Ω)
Power in AC P = VrmsIrmscosφ cosφ = power factor Watt (W)
Resonant Frequency f₀ = 1/(2π√LC) When XL = XC Hertz (Hz)
Quality Factor Q = ω₀L/R Sharpness of resonance Dimensionless

6. Optics (Ray & Wave)

Concept Formula Description SI Unit
Snell’s Law n₁sinθ₁ = n₂sinθ₂ Refraction at interface Dimensionless
Mirror Formula 1/v + 1/u = 1/f u=object dist., v=image dist. —
Lens Formula 1/v – 1/u = 1/f Thin lens formula —
Magnification (Mirror) m = -v/u Linear magnification Dimensionless
Lens Maker’s Formula 1/f = (n-1)[1/R₁-1/R₂] Radii of curvature R₁, R₂ m⁻¹
Power of Lens P = 1/f (metres) In diopters Diopter (D)
Critical Angle sinC = 1/n For total internal reflection Degree
Refractive Index n = c/v c = speed of light in vacuum Dimensionless
Young’s Double Slit β = λD/d Fringe width; D = dist., d = slit sep. Meter (m)
Path Difference Δ = nλ (bright) Constructive interference condition Meter (m)
Resolving Power θ = 1.22λ/D Rayleigh criterion Radian
Diffraction (single slit) sinθ = mλ/a First minimum condition —

7. Dual Nature of Matter & Radiation

Concept Formula Description SI Unit
Photon Energy E = hf = hc/λ h = 6.626×10⁻³⁴ J·s Joule (J)
Photoelectric Effect KEmax = hf – φ φ = work function Joule (J)
Threshold Frequency f₀ = φ/h Minimum frequency for emission Hertz (Hz)
de Broglie Wavelength λ = h/mv = h/p Wave nature of particles Meter (m)
Einstein’s Photoelectric eV₀ = hf – φ V₀ = stopping potential Volt (V)
Momentum of Photon p = h/λ = E/c Photon momentum kg·m/s

8. Atoms & Nuclei

Concept Formula Description SI Unit
Bohr’s Radius rₙ = n²a₀ (a₀=0.529 Å) Radius of nth orbit in H-atom Angstrom (Å)
Bohr’s Energy Eₙ = -13.6/n² eV Energy of nth orbit eV
Energy Emitted E = E₂ – E₁ = hf Photon emitted during transition Joule (J)
Rydberg Formula 1/λ = R(1/n₁²-1/n₂²) R = 1.097×10⁷ m⁻¹ m⁻¹
Nuclear Radius R = R₀A^(1/3) R₀ = 1.2×10⁻¹⁵ m Meter (m)
Mass-Energy Equiv. E = mc² c = 3×10⁸ m/s Joule (J)
Binding Energy BE = [Zmp+(A-Z)mn-M]c² Z=protons, A=mass number MeV
Radioactive Decay N = N₀e^(-λt) λ = decay constant Atoms
Half-Life T½ = 0.693/λ Time for N to reduce to N/2 Second (s)
Activity A = λN = A₀e^(-λt) Decays per second Becquerel (Bq)

9. Semiconductor Electronics

Concept Formula Description SI Unit
Current in Diode I = I₀(e^(V/ηVT)-1) Shockley diode equation Ampere (A)
Transistor Current IC = βIB β = current gain (CE config) Ampere (A)
Transistor Gain β = IC/IB Common emitter current gain Dimensionless
α (CB gain) α = IC/IE = β/(1+β) Common base current gain Dimensionless
Voltage Gain AV = β × (RC/Rin) Amplifier voltage gain Dimensionless
Logic: NOT Gate Y = Ā Output is complement of input —
Logic: AND Gate Y = A·B Output is 1 only if both inputs 1 —
Logic: OR Gate Y = A+B Output is 1 if any input is 1 —
Logic: NAND Gate Y = (A·B)̄ NOT AND (universal gate) —
Logic: NOR Gate Y = (A+B)̄ NOT OR (universal gate) —

10. Communication Systems

Concept Formula Description SI Unit
Modulation Index m = Am/Ac Am = message, Ac = carrier amplitude Dimensionless
AM Bandwidth BW = 2fm fm = message signal frequency Hertz (Hz)
Channel Capacity C = B·log₂(1+S/N) Shannon-Hartley theorem bits/s
Range of Antenna d = √(2Rh) R = earth radius, h = antenna height Meter (m)
Sky Wave Range d = 2√(2Rh) Maximum range for sky wave Meter (m)

How to Remember Class 12 Physics Formulas

Remembering a large number of physics formulas can be challenging. Below are evidence-based strategies recommended by educators:

  1. Understand, Don’t Just Memorize: Every formula has a physical meaning. For example, F = ma tells us that force causes acceleration proportional to mass. Understanding the concept makes recall effortless.
  2. Create a Dedicated Formula Notebook: Write each formula chapter-wise with one formula per line. Revisit this notebook daily during exam preparation.
  3. Use Mnemonics and Acronyms: For Kirchhoff’s Laws, remember ‘KCL = currents at junctions, KVL = voltages in loops’. Create your own memory aids.
  4. Solve Problems Daily: The best way to internalize formulas is to apply them. Solve at least 5–10 numerical problems per chapter.
  5. Flashcard System: Write the formula on one side and its meaning/variables on the other. This spaced repetition technique improves long-term retention.
  6. Group Related Formulas: Learn capacitor and resistor series/parallel formulas together since they follow opposite patterns.
  7. Visualization: Draw diagrams alongside formulas (e.g., draw a capacitor when writing C = ε₀A/d).
  8. Teach Others: Explaining a formula to a peer or studying in groups reinforces your own understanding significantly.

Important Physical Constants

Constant Symbol & Value SI Unit
Speed of Light c = 3×10⁸ m/s m/s
Planck’s Constant h = 6.626×10⁻³⁴ J·s J·s
Elementary Charge e = 1.6×10⁻¹⁹ C Coulomb (C)
Mass of Electron mₑ = 9.1×10⁻³¹ kg kg
Mass of Proton mₚ = 1.67×10⁻²⁷ kg kg
Permittivity (free space) ε₀ = 8.85×10⁻¹² C²/N·m² C²/N·m²
Permeability (free space) μ₀ = 4π×10⁻⁷ T·m/A T·m/A
Boltzmann’s Constant k = 1.38×10⁻²³ J/K J/K
Avogadro’s Number Nₐ = 6.022×10²³ mol⁻¹ mol⁻¹
Gravitational Constant G = 6.67×10⁻¹¹ N·m²/kg² N·m²/kg²

Class 12 Physics Formulas related FAQs

What are the most important physics formulas for Class 12?

The most important formulas include Coulomb’s Law, Ohm’s Law, Faraday’s Laws, lens/mirror formulas, Einstein’s photoelectric equation, Bohr’s model equations, and radioactive decay laws. These cover the maximum weightage chapters in CBSE Class 12 Physics.

How can I memorize all Class 12 physics formulas?

Organize formulas chapter-wise and create flashcards. Practice daily derivations, understand the physical meaning behind each formula, use mnemonics, solve NCERT problems regularly, and revise a formula sheet before bed. Consistent revision is more effective than cramming.

Which chapter has the most formulas in Class 12 Physics?

Electrostatics, Current Electricity, and Optics typically have the highest number of formulas. Magnetism and Electromagnetic Induction also contribute significantly to the formula count in Class 12 Physics.

Is the physics formula sheet enough for board exams?

A comprehensive formula sheet is a vital reference tool, but success in boards requires understanding derivations, conceptual clarity, and regular problem-solving practice. Formula sheets supplement study, they do not replace it.

Where can I download a Class 12 Physics formula PDF?

You can download formula sheets from NCERT’s official website (ncert.nic.in), CBSE’s academic portal, or trusted educational platforms. Ensure the source aligns with the latest CBSE syllabus for accuracy.

What is the formula for energy stored in a capacitor?

The energy stored in a capacitor is given by U = ½CV² = Q²/2C = ½QV, where C is capacitance, V is voltage across the capacitor, and Q is the charge stored.

What is de Broglie’s wavelength formula and its significance?

de Broglie’s formula λ = h/mv (or h/p) states that every moving particle has an associated wavelength. It establishes the wave-particle duality of matter and is fundamental to quantum mechanics and modern physics.

How is the transformer formula derived?

The transformer equation Vs/Vp = Ns/Np is derived using Faraday’s law of electromagnetic induction. In an ideal transformer, the EMF induced in each winding is proportional to the number of turns, assuming no flux leakage.

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