CBSE Class 12 Physics All Formulas 2027 — Chapter-wise PDF

In short: CBSE Class 12 Physics carries 70 marks in theory. Formulas and derivations account for 40-50% of the paper. This guide covers all chapter-wise formulas — bookmark it for quick revision before exams.

Unit I: Electrostatics

Chapter 1: Electric Charges and Fields

Coulomb's Law

F = kq₁q₂/r² = (1/4πε₀) × q₁q₂/r²

k = 9 × 10⁹ Nm²/C²
ε₀ = 8.85 × 10⁻¹² C²/Nm²

Electric Field

E = F/q₀ = kQ/r²
Unit: N/C or V/m

Electric Field due to Dipole

• Axial: E = 2kp/r³ (for r >> a)
• Equatorial: E = kp/r³ (for r >> a)

Electric Dipole Moment

p = q × 2a (Unit: C·m)

Torque on Dipole

τ = pE sin θ

Electric Flux

φ = E·A = EA cos θ (Unit: Nm²/C)

Gauss's Law

∮E·dA = q/ε₀

Electric Field Applications (Gauss's Law)

• Infinite line charge: E = λ/(2πε₀r)
• Infinite plane sheet: E = σ/(2ε₀)
• Charged sphere (outside): E = kQ/r²
• Charged sphere (inside): E = kQr/R³

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Chapter 2: Electrostatic Potential and Capacitance

Electric Potential

V = W/q = kQ/r (Unit: Volt)

Relation between E and V

E = -dV/dr

Capacitance

C = Q/V (Unit: Farad)

Parallel Plate Capacitor

C = ε₀A/d
With dielectric: C = Kε₀A/d

Energy Stored in Capacitor

U = ½CV² = ½QV = Q²/2C

Capacitors in Series

1/C = 1/C₁ + 1/C₂ + 1/C₃

Capacitors in Parallel

C = C₁ + C₂ + C₃

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Unit II: Current Electricity

Chapter 3: Current Electricity

Electric Current

I = Q/t = dQ/dt (Unit: Ampere)

Drift Velocity

vd = eEτ/m = I/(neA)

Ohm's Law

V = IR

Resistance

R = ρl/A
R = R₀(1 + αΔT)

Resistors in Series

R = R₁ + R₂ + R₃

Resistors in Parallel

1/R = 1/R₁ + 1/R₂ + 1/R₃

Electric Power

P = VI = I²R = V²/R (Unit: Watt)

Electrical Energy

E = Pt = VIt (1 kWh = 3.6 × 10⁶ J)

EMF and Internal Resistance

ε = V + Ir
I = ε/(R + r)

Kirchhoff's Laws

• Junction Rule: ΣI = 0
• Loop Rule: ΣV = 0

Wheatstone Bridge (Balanced)

P/Q = R/S

Meter Bridge

R/S = l/(100-l)

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Unit III: Magnetic Effects of Current

Chapter 4: Moving Charges and Magnetism

Lorentz Force

F = qvB sin θ

Force on Current-carrying Conductor

F = BIl sin θ

Biot-Savart Law

dB = (μ₀/4π) × (Idl sin θ)/r²
μ₀ = 4π × 10⁻⁷ Tm/A

Magnetic Field due to Straight Conductor

B = μ₀I/(2πr)

Magnetic Field at Center of Circular Loop

B = μ₀I/(2r)
For n turns: B = μ₀nI/(2r)

Ampere's Circuital Law

∮B·dl = μ₀I

Magnetic Field inside Solenoid

B = μ₀nI (n = turns per unit length)

Force between Parallel Conductors

F/l = μ₀I₁I₂/(2πd)

Torque on Current Loop

τ = NIAB sin θ = MB sin θ

Magnetic Dipole Moment

M = NIA (Unit: A·m²)

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Chapter 5: Magnetism and Matter

Magnetic Field Intensity

H = B/μ₀ - M (Unit: A/m)

Magnetic Susceptibility

χ = M/H

Magnetic Permeability

μ = μ₀(1 + χ) = μ₀μᵣ

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Unit IV: Electromagnetic Induction and AC

Chapter 6: Electromagnetic Induction

Magnetic Flux

φ = BA cos θ (Unit: Weber)

Faraday's Law

ε = -dφ/dt = -N(dφ/dt)

Motional EMF

ε = Blv

Self Inductance

ε = -L(dI/dt)
L = Nφ/I (Unit: Henry)

Self Inductance of Solenoid

L = μ₀n²Al

Energy Stored in Inductor

U = ½LI²

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Chapter 7: Alternating Current

AC Voltage and Current

V = V₀ sin ωt
I = I₀ sin(ωt ± φ)

RMS Values

Vrms = V₀/√2 = 0.707V₀
Irms = I₀/√2

Reactance

• Inductive: XL = ωL = 2πfL
• Capacitive: XC = 1/(ωC) = 1/(2πfC)

Impedance in LCR Circuit

Z = √[R² + (XL - XC)²]

Power in AC Circuit

P = VrmsIrms cos φ
Power Factor: cos φ = R/Z

Resonance Frequency

f₀ = 1/(2π√LC)
At resonance: Z = R (minimum)

Transformer

Vs/Vp = Ns/Np = Ip/Is

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Unit V: Electromagnetic Waves

Chapter 8: Electromagnetic Waves

Speed of EM Waves

c = 1/√(μ₀ε₀) = 3 × 10⁸ m/s

Relation between E and B

c = E₀/B₀

Energy Density

u = ½ε₀E² = B²/(2μ₀)

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Unit VI: Optics

Chapter 9: Ray Optics

Mirror Formula

1/v + 1/u = 1/f

Magnification (Mirror)

m = -v/u = h'/h

Lens Formula

1/v - 1/u = 1/f

Lens Maker's Formula

1/f = (n-1)(1/R₁ - 1/R₂)

Power of Lens

P = 1/f (Unit: Dioptre)

Combination of Lenses

P = P₁ + P₂
1/f = 1/f₁ + 1/f₂

Refraction at Spherical Surface

n₂/v - n₁/u = (n₂-n₁)/R

Prism

δ = i + e - A
At minimum deviation: i = e, r = A/2
n = sin[(A+δm)/2] / sin(A/2)

Total Internal Reflection

sin ic = 1/n (Critical angle)

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Chapter 10: Wave Optics

Young's Double Slit

Fringe width: β = λD/d
Bright fringe: y = nλD/d
Dark fringe: y = (2n-1)λD/2d

Single Slit Diffraction

Central maximum width = 2λD/a

Brewster's Law

tan ip = n (Polarizing angle)

Malus Law

I = I₀ cos²θ

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Unit VII: Dual Nature of Matter

Chapter 11: Dual Nature of Radiation and Matter

Photoelectric Effect (Einstein's Equation)

hν = W + ½mv²max
hν = hν₀ + KEmax

Threshold Frequency

W = hν₀ (Work function)

Stopping Potential

eV₀ = ½mv²max = hν - W

de Broglie Wavelength

λ = h/p = h/mv
λ = h/√(2mKE)
λ = h/√(2meV)

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Unit VIII: Atoms and Nuclei

Chapter 12: Atoms

Bohr's Model

Radius: rn = n²h²ε₀/(πme²) = 0.53n² Å
Energy: En = -13.6/n² eV
Velocity: vn = e²/(2ε₀nh)

Rydberg Formula

1/λ = R(1/n₁² - 1/n₂²)
R = 1.097 × 10⁷ m⁻¹

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Chapter 13: Nuclei

Mass-Energy Relation

E = mc²

Binding Energy

BE = [Zmp + (A-Z)mn - M]c²
BE per nucleon = BE/A

Radioactive Decay

N = N₀e^(-λt)
Activity: A = λN = A₀e^(-λt)

Half-life

T½ = 0.693/λ = ln2/λ

Mean Life

τ = 1/λ

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Unit IX: Electronic Devices

Chapter 14: Semiconductor Electronics

Conductivity

σ = e(neμe + nhμh)

Diode Equation

I = I₀(e^(eV/kT) - 1)

Transistor Relations

IE = IB + IC
α = IC/IE (0.95-0.99)
β = IC/IB (20-500)
β = α/(1-α)

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Quick Reference: Most Important Formulas

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Frequently Asked Questions

How many formulas should I memorize for CBSE Class 12 Physics?

Around 80-100 key formulas. Focus on derivations too — understanding how formulas are derived helps you remember them and apply them correctly.

Which chapters have the most formulas?

1. Electrostatics (Chapter 1-2) — 20+ formulas
2. Current Electricity (Chapter 3) — 15+ formulas
3. Optics (Chapter 9-10) — 15+ formulas
4. Modern Physics (Chapter 11-13) — 15+ formulas

How to remember Physics formulas?

1. Understand the derivation first
2. Practice numerical problems daily
3. Make formula flashcards
4. Revise formulas every morning for 15 minutes

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