Physics Formulas for Class 12 – All Chapters
Physics can feel overwhelming when you’re staring at a stack of textbooks before your Class 12 exams. But here’s the secret weapon that can transform your preparation: mastering physics formulas for class 12! Whether you’re aiming for top marks in your board exams or preparing for competitive tests like JEE or NEET, having all formulas of physics class 12 at your fingertips is absolutely crucial.
This comprehensive guide brings together every important physics formulas for class 12 from all chapters, making your revision systematic and stress-free. Students often search for physics formulas for class 12 pdf free download to have offline access, and this guide serves as your complete reference.
Chapter-Wise List of Physics Formulas for Class 12
Understanding Class 12 physics formulas becomes much easier when they’re organised chapter-wise. The all formulas of physics class 12 CBSE curriculum covers 14 essential chapters, each containing fundamental equations that form the backbone of physics concepts. These physics formulas for Class 12 CBSE board examinations are carefully selected to cover all important topics that frequently appear in board exams and competitive tests. Let’s explore each chapter’s key formulas with their symbols and SI units for better understanding of physics class 12 formulas.
Chapter 1: Electric Charges and Fields
Introduces the concept of electric charge, forces between charges (Coulomb’s law), and the electric field. Gauss’s Law is a key highlight for solving symmetrical charge distribution problems.
| Formula | Description | SI Unit |
| F = k(q₁q₂)/r² | Coulomb’s Law | N (Newton) |
| E = F/q | Electric Field | N/C or V/m |
| E = kQ/r² | Electric Field due to Point Charge | N/C |
| E = kQ/4πε₀r² | Electric Field (Alternative Form) | N/C |
| φ = E⋅A cosθ | Electric Flux | N⋅m²/C |
| φ = Q/ε₀ | Gauss’s Law | N⋅m²/C |
| E = λ/2πε₀r | Electric Field due to Line Charge | N/C |
| E = σ/2ε₀ | Electric Field due to Infinite Sheet | N/C |
| F = qE | Force on Charge in Electric Field | N |
| p = qd | Electric Dipole Moment | C⋅m |
| E = 2kp/r³ | Electric Field on Axial Line of Dipole | N/C |
| E = kp/r³ | Electric Field on Equatorial Line of Dipole | N/C |
| τ = pE sinθ | Torque on Electric Dipole | N⋅m |
| U = -pE cosθ | Potential Energy of Dipole | J |
| λ = Q/L | Linear Charge Density | C/m |
| σ = Q/A | Surface Charge Density | C/m² |
| ρ = Q/V | Volume Charge Density | C/m³ |
Constants:
- k = 9 × 10⁹ N⋅m²/C²
- ε₀ = 8.85 × 10⁻¹² C²/N⋅m²
Diagrams:
Chapter 2: Electrostatic Potential and Capacitance
Covers electric potential, capacitors, and energy stored in electric fields. Focuses on how charge behaves in different capacitor systems.
| Formula | Description | SI Unit |
| V = W/q | Electric Potential | V (Volt) |
| V = kQ/r | Potential due to Point Charge | V |
| V = kQ/4πε₀r | Potential (Alternative Form) | V |
| W = q(V₂ – V₁) | Work Done in Moving Charge | J |
| E = -dV/dr | Electric Field from Potential | N/C |
| V = kp cosθ/r² | Potential due to Dipole | V |
| C = Q/V | Capacitance | F (Farad) |
| C = ε₀A/d | Parallel Plate Capacitor | F |
| C = 4πε₀R | Capacitance of Isolated Sphere | F |
| C = 2πε₀L/ln(b/a) | Capacitance of Cylindrical Capacitor | F |
| K = C/C₀ | Dielectric Constant | Dimensionless |
| C = KC₀ | Capacitance with Dielectric | F |
| U = ½CV² | Energy Stored in Capacitor | J |
| U = ½QV | Energy Stored (Alternative) | J |
| U = Q²/2C | Energy Stored (Alternative) | J |
| u = ½ε₀E² | Energy Density | J/m³ |
| 1/C = 1/C₁ + 1/C₂ + 1/C₃ | Capacitors in Series | F |
| C = C₁ + C₂ + C₃ | Capacitors in Parallel | F |
| F = ½ε₀E²A | Force between Capacitor Plates | N |
Diagrams:
Chapter 3: Current Electricity
Deals with electric current, Ohm’s Law, combination of resistors, EMF, and the heating effect of electric current (Joule’s Law).
| Formula | Description | SI Unit |
| I = Q/t | Current | A (Ampere) |
| I = nAve | Current (Microscopic Form) | A |
| vd = I/nAe | Drift Velocity | m/s |
| V = IR | Ohm’s Law | V (Volt) |
| R = ρL/A | Resistance | Ω (Ohm) |
| G = 1/R | Conductance | S (Siemens) |
| σ = 1/ρ | Conductivity | S/m |
| ρ = ρ₀[1 + α(T – T₀)] | Temperature Dependence of Resistivity | Ω⋅m |
| J = I/A | Current Density | A/m² |
| J = σE | Current Density (Ohm’s Law) | A/m² |
| P = VI | Power | W (Watt) |
| P = I²R | Power (Alternative) | W |
| P = V²/R | Power (Alternative) | W |
| H = I²Rt | Heat Produced (Joule’s Law) | J |
| Rs = R₁ + R₂ + R₃ | Resistors in Series | Ω |
| 1/Rp = 1/R₁ + 1/R₂ + 1/R₃ | Resistors in Parallel | Ω |
| ε = I(R + r) | EMF of Cell | V |
| ε = V + Ir | EMF (Alternative Form) | V |
| η = R/(R + r) | Efficiency of Cell | Dimensionless |
| I = ε/(R + r) | Current from Cell | A |
| V = ε – Ir | Terminal Voltage | V |
| Req = nr + R/n | Cells in Series | Ω |
| Req = r/n + R | Cells in Parallel | Ω |
| I₁R₁ = I₂R₂ | Current Division Rule | A |
| V₁/V₂ = R₁/R₂ | Voltage Division Rule | V |
Diagrams:
Chapter 4: Moving Charges and Magnetism
Discusses magnetic effects of electric current, Lorentz force, and the motion of charged particles in magnetic fields. Key for understanding cyclotrons and magnetic fields due to wires and loops.
| Formula | Description | SI Unit |
| F = q(v × B) | Lorentz Force (Vector Form) | N (Newton) |
| F = qvB sinθ | Lorentz Force (Scalar Form) | N |
| F = q(E + v × B) | Complete Lorentz Force | N |
| F = BIL sinθ | Force on Current-Carrying Wire | N |
| F = BI∫dl | Force on Current Element | N |
| B = μ₀I/2πr | Magnetic Field due to Straight Wire | T (Tesla) |
| B = μ₀I/4πr² | Magnetic Field due to Current Element | T |
| B = μ₀IR²/2(R² + x²)^(3/2) | Magnetic Field on Axis of Circular Loop | T |
| B = μ₀I/2R | Magnetic Field at Centre of Circular Loop | T |
| B = μ₀nI | Magnetic Field inside Solenoid | T |
| B = μ₀nI/2 | Magnetic Field at End of Solenoid | T |
| B = μ₀NI/L | Magnetic Field inside Toroid | T |
| r = mv/qB | Radius of Circular Path | m |
| T = 2πm/qB | Time Period of Circular Motion | s |
| f = qB/2πm | Cyclotron Frequency | Hz |
| ω = qB/m | Angular Frequency | rad/s |
| p = qBr | Momentum of Charged Particle | kg⋅m/s |
| KE = q²B²r²/2m | Kinetic Energy | J |
| μ = IA | Magnetic Dipole Moment | A⋅m² |
| τ = μ × B | Torque on Magnetic Dipole | N⋅m |
| U = -μ⋅B | Potential Energy of Dipole | J |
| F = μ(dB/dx) | Force on Magnetic Dipole | N |
| dB = μ₀I dl × r̂/4πr² | Biot-Savart Law | T |
Constants:
- μ₀ = 4π × 10⁻⁷ T⋅m/A
Diagrams:
Chapter 5: Magnetism and Matter
Explores Earth’s magnetism and classification of magnetic materials. Introduces magnetic susceptibility, permeability, and behavior in external fields.
| Formula | Description | SI Unit |
| M = mL | Magnetic Moment | A⋅m² |
| m = IA | Magnetic Dipole Moment | A⋅m² |
| B = μ₀(H + M) | Magnetic Field in Material | T |
| H = B/μ₀ – M | Magnetic Field Intensity | A/m |
| I = M/H | Magnetic Intensity | A/m |
| χ = M/H | Magnetic Susceptibility | Dimensionless |
| μ = B/H | Magnetic Permeability | H/m |
| μᵣ = μ/μ₀ | Relative Permeability | Dimensionless |
| μᵣ = 1 + χ | Relation between μᵣ and χ | Dimensionless |
| B = μ₀H(1 + χ) | Magnetic Field with Susceptibility | T |
| B = μ₀μᵣH | Magnetic Field with Relative Permeability | T |
| F = χVB(dB/dx) | Force on Magnetic Material | N |
| μB = eℏ/2m | Bohr Magneton | J/T |
| μ = -gμB√(J(J+1)) | Magnetic Moment of Atom | J/T |
| χ = C/T | Curie’s Law (Paramagnetic) | K |
| χ = C/(T – TC) | Curie-Weiss Law (Ferromagnetic) | K |
| Hc = -M/χ | Coercive Field | A/m |
Material Classifications:
- Diamagnetic: χ < 0, μᵣ < 1
- Paramagnetic: χ > 0, μᵣ > 1
- Ferromagnetic: χ >> 1, μᵣ >> 1
Chapter 6: Electromagnetic Induction
Focuses on Faraday’s and Lenz’s Laws of induction, EMF generation, inductance, and LR circuits. Crucial for understanding transformers and electric generators.
| Formula | Description | SI Unit |
| ε = -dφ/dt | Faraday’s Law | V (Volt) |
| ε = -N(dφ/dt) | Faraday’s Law for N Turns | V |
| ε = BLv | Motional EMF | V |
| ε = ½BLv² | Motional EMF (Rotating Rod) | V |
| φ = BA cosθ | Magnetic Flux | Wb (Weber) |
| φ = ∫B⋅dA | Magnetic Flux (General) | Wb |
| ε = -L(dI/dt) | Self-Induced EMF | V |
| ε = -M(dI/dt) | Mutually Induced EMF | V |
| L = φ/I | Self-Inductance | H (Henry) |
| L = μ₀n²Al | Self-Inductance of Solenoid | H |
| L = μ₀N²A/l | Self-Inductance (Alternative) | H |
| M = φ₂/I₁ = φ₁/I₂ | Mutual Inductance | H |
| M = μ₀N₁N₂A/l | Mutual Inductance of Solenoids | H |
| k = M/√(L₁L₂) | Coupling Coefficient | Dimensionless |
| U = ½LI² | Energy Stored in Inductor | J |
| u = B²/2μ₀ | Magnetic Energy Density | J/m³ |
| F = BIL | Force on Conductor | N |
| P = BILv | Power Dissipated | W |
| I = I₀(1 – e^(-Rt/L)) | Current Growth in LR Circuit | A |
| I = I₀e^(-Rt/L) | Current Decay in LR Circuit | A |
| τ = L/R | Time Constant of LR Circuit | s |
| ε = BLv sinωt | AC Motional EMF | V |
Diagrams:
Chapter 7: Alternating Current
Covers AC circuits, reactance, impedance, power in AC, and resonance. Includes key quantities like RMS, average current, and power factor.
| Formula | Description | SI Unit |
| I = I₀ sinωt | Instantaneous AC Current | A (Ampere) |
| V = V₀ sinωt | Instantaneous AC Voltage | V (Volt) |
| I = I₀ sin(ωt + φ) | AC Current with Phase | A |
| V = V₀ sin(ωt + φ) | AC Voltage with Phase | V |
| Iᵣₘₛ = I₀/√2 | RMS Current | A |
| Vᵣₘₛ = V₀/√2 | RMS Voltage | V |
| Iₐᵥₑ = 2I₀/π | Average Current | A |
| Vₐᵥₑ = 2V₀/π | Average Voltage | V |
| XL = ωL = 2πfL | Inductive Reactance | Ω |
| XC = 1/ωC = 1/2πfC | Capacitive Reactance | Ω |
| Z = √(R² + (XL – XC)²) | Impedance | Ω |
| tanφ = (XL – XC)/R | Phase Angle | Dimensionless |
| VL = IXL | Voltage across Inductor | V |
| VC = IXC | Voltage across Capacitor | V |
| VR = IR | Voltage across Resistor | V |
| P = VᵣₘₛIᵣₘₛ cosφ | Average Power | W |
| P = I²ᵣₘₛR | Power Dissipated | W |
| Q = VᵣₘₛIᵣₘₛ sinφ | Reactive Power | VAr |
| S = VᵣₘₛIᵣₘₛ | Apparent Power | VA |
| cosφ = R/Z | Power Factor | Dimensionless |
| f₀ = 1/2π√(LC) | Resonant Frequency | Hz |
| ω₀ = 1/√(LC) | Angular Resonant Frequency | rad/s |
| Q = ω₀L/R = 1/ω₀RC | Quality Factor | Dimensionless |
| BW = f₀/Q | Bandwidth | Hz |
| Z₀ = √(L/C) | Characteristic Impedance | Ω |
| Np/Ns = Vp/Vs = Is/Ip | Transformer Equation | Dimensionless |
| η = PsVsIs cosφs/PpVpIp cosφp | Transformer Efficiency | Dimensionless |
Diagrams:
Chapter 8: Electromagnetic Waves
Discusses the nature, propagation, and characteristics of EM waves including energy transport and the electromagnetic spectrum.
| Formula | Description | SI Unit |
| c = 1/√(μ₀ε₀) | Speed of Light in Vacuum | m/s |
| c = fλ | Wave Equation | m/s |
| v = fλ | Wave Speed in Medium | m/s |
| n = c/v | Refractive Index | Dimensionless |
| E = hf = hc/λ | Energy of Photon | J (Joule) |
| E = pc | Energy-Momentum Relation | J |
| p = E/c = h/λ | Momentum of Photon | kg⋅m/s |
| I = P/A | Intensity of Wave | W/m² |
| I = ε₀cE₀²/2 | Intensity in terms of Electric Field | W/m² |
| I = B₀²/2μ₀c | Intensity in terms of Magnetic Field | W/m² |
| E₀/B₀ = c | Ratio of Electric to Magnetic Field | m/s |
| u = ε₀E²/2 + B²/2μ₀ | Energy Density | J/m³ |
| S = E × B/μ₀ | Poynting Vector | W/m² |
| P = uAc | Power Carried by Wave | W |
| Pᵣₐd = I/c | Radiation Pressure | N/m² |
| F = PA | Radiation Force | N |
| λ = c/f | Wavelength in Vacuum | m |
| T = 1/f | Time Period | s |
| ω = 2πf | Angular Frequency | rad/s |
| k = 2π/λ | Wave Number | m⁻¹ |
| E = E₀ sin(kx – ωt) | Electric Field Wave | V/m |
| B = B₀ sin(kx – ωt) | Magnetic Field Wave | T |
| ε = ε₀εᵣ | Permittivity of Medium | F/m |
| μ = μ₀μᵣ | Permeability of Medium | H/m |
| v = 1/√(εμ) | Speed in Medium | m/s |
Constants:
- c = 3 × 10⁸ m/s
- h = 6.63 × 10⁻³⁴ J⋅s
Electromagnetic Spectrum:
- Radio waves: λ > 1 m
- Microwaves: 1 mm < λ < 1 m
- Infrared: 700 nm < λ < 1 mm
- Visible: 400 nm < λ < 700 nm
- Ultraviolet: 10 nm < λ < 400 nm
- X-rays: 0.01 nm < λ < 10 nm
- Gamma rays: λ < 0.01 nm
Diagrams:
Chapter 9: Ray Optics and Optical Instruments
Explores reflection, refraction, lens/mirror formulas, and optical instruments like microscopes and telescopes. Critical for image formation and power of lenses.
| Formula | Description | SI Unit |
| 1/f = 1/v + 1/u | Lens Formula | m⁻¹ |
| 1/f = 1/v + 1/u | Mirror Formula | m⁻¹ |
| m = v/u | Linear Magnification | Dimensionless |
| m = h’/h | Magnification (Height Ratio) | Dimensionless |
| P = 1/f | Power of Lens | D (Dioptre) |
| P = P₁ + P₂ | Power of Combined Lenses | D |
| n₁sinθ₁ = n₂sinθ₂ | Snell’s Law | Dimensionless |
| sinθc = n₂/n₁ | Critical Angle | Dimensionless |
| sinθc = 1/n | Critical Angle (Denser to Rarer) | Dimensionless |
| 1/f = (n-1)(1/R₁ – 1/R₂) | Lens Maker’s Formula | m⁻¹ |
| 1/f = (n-1)/R | Lens Maker’s (Equiconvex) | m⁻¹ |
| n = sinθ₁/sinθ₂ | Refractive Index | Dimensionless |
| n = c/v | Refractive Index (Speed) | Dimensionless |
| n = λ₀/λ | Refractive Index (Wavelength) | Dimensionless |
| δ = θ₁ + θ₂ – A | Deviation in Prism | Degree |
| δₘ = 2i – A | Minimum Deviation | Degree |
| n = sin((A + δₘ)/2)/sin(A/2) | Refractive Index of Prism | Dimensionless |
| r₁ + r₂ = A | Relation in Prism | Degree |
| A = r₁ + r₂ | Prism Angle | Degree |
| fe = D/f₀ | Magnifying Power of Telescope | Dimensionless |
| m = D/f | Magnifying Power of Microscope | Dimensionless |
| m = (D/f₀)(1 + D/fe) | Compound Microscope | Dimensionless |
| m = D/f | Simple Microscope | Dimensionless |
| f = R/2 | Focal Length of Spherical Mirror | m |
| 1/R = 1/f | Mirror Curvature | m⁻¹ |
| h’ = -h(v/u) | Image Height | m |
| M = m₀ × me | Total Magnification | Dimensionless |
| Resolving Power = 1.22λ/D | Resolving Power of Telescope | Dimensionless |
| dθ = 1.22λ/D | Angular Resolution | rad |
Diagrams:
Chapter 10: Wave Optics
Covers interference, diffraction, and polarization of light. Focuses on wave-based behavior of light and applications like Young’s double-slit experiment.
| Formula | Description | SI Unit |
| λ = c/f | Wavelength | m (Metre) |
| v = fλ | Wave Speed | m/s |
| n = c/v | Refractive Index | Dimensionless |
| y = (nλD)/d | Fringe Position (Young’s Experiment) | m |
| β = λD/d | Fringe Width | m |
| Δx = β = λD/d | Fringe Separation | m |
| I = I₁ + I₂ + 2√(I₁I₂)cosφ | Intensity in Interference | W/m² |
| I = I₀cos²(φ/2) | Intensity (Two Source) | W/m² |
| φ = (2π/λ)Δ | Phase Difference | rad |
| Δ = S₂P – S₁P | Path Difference | m |
| φ = (2π/λ)d sinθ | Phase Difference (General) | rad |
| dsinθ = nλ | Diffraction Grating | m |
| N = 1/d | Grating Element | m⁻¹ |
| sinθ = nλ/a | Single Slit Diffraction | Dimensionless |
| I = I₀(sin²α/α²) | Intensity in Single Slit | W/m² |
| α = (πa sinθ)/λ | Diffraction Parameter | rad |
| R = λ/Δλ | Resolving Power | Dimensionless |
| R = mN | Resolving Power of Grating | Dimensionless |
| θ = λ/a | Angular Width of Central Maximum | rad |
| dθ = λ/D | Angular Resolution | rad |
| μ = n₁/n₂ | Relative Refractive Index | Dimensionless |
| sinθp = n₂/n₁ | Polarising Angle | Dimensionless |
| tanθp = n | Brewster’s Law | Dimensionless |
| I = I₀cos²θ | Malus’ Law | W/m² |
Chapter 11: Dual Nature of Radiation and Matter
Discusses photoelectric effect, de Broglie wavelength, and quantum concepts of light and matter. Lays foundation for modern physics.
| Formula | Description | SI Unit |
| E = hf = hc/λ | Planck’s Equation | J (Joule) |
| KEmax = hf – φ | Photoelectric Effect | J |
| KEmax = hf – hf₀ | Photoelectric Effect (Alternative) | J |
| hf₀ = φ | Work Function | J |
| eV₀ = hf – φ | Stopping Potential | eV |
| λ = h/p | de Broglie Wavelength | m |
| λ = h/mv | de Broglie Wavelength (Particles) | m |
| λ = h/√(2mKE) | de Broglie Wavelength (KE Form) | m |
| λ = h/√(2meV) | de Broglie Wavelength (Electrons) | m |
| p = h/λ | Momentum | kg⋅m/s |
| E = pc | Energy-Momentum Relation (Photons) | J |
| E² = (pc)² + (mc²)² | Energy-Momentum Relation (Particles) | J |
| hf = KEmax + φ | Einstein’s Photoelectric Equation | J |
| ν₀ = φ/h | Threshold Frequency | Hz |
| λ₀ = hc/φ | Threshold Wavelength | m |
| I = nhf | Intensity of Light | W/m² |
| N = I/hf | Photon Flux | photons/s/m² |
| p = E/c = hf/c | Photon Momentum | kg⋅m/s |
| K = ½mv² | Kinetic Energy | J |
| λc = h/mc | Compton Wavelength | m |
| Δλ = λc(1 – cosθ) | Compton Scattering | m |
| E = hf = hc/λ | Photon Energy | J |
| Group velocity = dω/dk | Group Velocity | m/s |
| Phase velocity = ω/k | Phase Velocity | m/s |
Chapter 12: Atoms
Explains the structure of atoms, Bohr’s model, and energy transitions. Introduces energy levels, spectral lines, and atomic constants.
| Formula | Description | SI Unit |
| rn = n²r₀ | Bohr’s Radius | m |
| r₀ = ε₀h²/πme² | Bohr Radius Constant | m |
| En = -13.6/n² | Energy Levels (Hydrogen) | eV |
| En = -me⁴/8ε₀²h²n² | Energy Levels (Detailed) | J |
| E∞ = 13.6 eV | Ionisation Energy of Hydrogen | eV |
| f = (E₂ – E₁)/h | Frequency of Emitted Photon | Hz |
| λ = hc/(E₂ – E₁) | Wavelength of Emitted Photon | m |
| 1/λ = R(1/n₁² – 1/n₂²) | Rydberg Formula | m⁻¹ |
| R = me⁴/8ε₀²h³c | Rydberg Constant | m⁻¹ |
| L = √(l(l+1))ℏ | Orbital Angular Momentum | J⋅s |
| Lz = mlℏ | z-component of Angular Momentum | J⋅s |
| μ = -μB√(j(j+1)) | Magnetic Moment | J/T |
| μB = eℏ/2m | Bohr Magneton | J/T |
| vn = e²/2ε₀hn | Orbital Velocity | m/s |
| Tn = 8ε₀²h³n³/me⁴ | Time Period | s |
| fn = me⁴/8ε₀²h³n³ | Orbital Frequency | Hz |
| KE = 13.6/n² | Kinetic Energy | eV |
| PE = -27.2/n² | Potential Energy | eV |
| E = KE + PE | Total Energy | eV |
| Z = 1 (for Hydrogen) | Atomic Number | Dimensionless |
| En = -13.6Z²/n² | Energy for Hydrogen-like atoms | eV |
| a = me²c²/2ℏ | Fine Structure Constant | Dimensionless |
Constants:
- r₀ = 0.529 × 10⁻¹⁰ m
- ℏ = h/2π = 1.055 × 10⁻³⁴ J⋅s
- R = 1.097 × 10⁷ m⁻¹
Diagrams:
Chapter 13: Nuclei
Covers nuclear structure, radioactivity, nuclear binding energy, and decay laws. Important for understanding energy release in nuclear reactions.
| Formula | Description | SI Unit |
| N = N₀e⁻λt | Radioactive Decay Law | Dimensionless |
| A = A₀e⁻λt | Activity Decay | Bq |
| T₁/₂ = ln2/λ = 0.693/λ | Half-Life | s |
| τ = 1/λ | Mean Life | s |
| A = λN | Activity | Bq (Becquerel) |
| A = dN/dt | Rate of Decay | Bq |
| λ = ln2/T₁/₂ | Decay Constant | s⁻¹ |
| N = N₀/2ⁿ | Decay after n half-lives | Dimensionless |
| BE = (Δm)c² | Binding Energy | J |
| BE = (Zmp + Nmn – M)c² | Binding Energy (Detailed) | J |
| BE/A = Binding Energy per nucleon | Binding Energy per Nucleon | J |
| Q = (mi – mf)c² | Q-Value of Reaction | J |
| R = R₀A^(1/3) | Nuclear Radius | m |
| ρ = 3A/4πR³ | Nuclear Density | kg/m³ |
| E = mc² | Mass-Energy Equivalence | J |
| 1 u = 931.5 MeV/c² | Atomic Mass Unit | J |
| r = 1.2 × 10⁻¹⁵ m | Nuclear Radius Constant | m |
| α-decay: ᴬzX → ᴬ⁻⁴z₋₂Y + ⁴₂He | Alpha Decay | – |
| β⁻-decay: ᴬzX → ᴬz₊₁Y + e⁻ + ν̄ | Beta Minus Decay | – |
| β⁺-decay: ᴬzX → ᴬz₋₁Y + e⁺ + ν | Beta Plus Decay | – |
| γ-decay: X* → X + γ | Gamma Decay | – |
| Kα = ½mv² | Kinetic Energy of Alpha | J |
| Eα/Eproduct = mproduct/mα | Energy Sharing in Alpha Decay | J |
| Cross-section = σ | Reaction Cross-section | m² |
Constants:
- R₀ = 1.2 × 10⁻¹⁵ m
- c = 3 × 10⁸ m/s
- 1 u = 1.66 × 10⁻²⁷ kg = 931.5 MeV/c²
Chapter 14: Semiconductor Electronics
Introduces semiconductors, diodes, transistors, and logic gates. Key for understanding electronics and modern devices.
| Formula | Description | SI Unit |
| I = I₀(e^(eV/kT) – 1) | Diode Current Equation | A |
| I = I₀(e^(qV/kT) – 1) | Diode Current (Alternative) | A |
| η = Pout/Pin × 100% | Efficiency | Percentage |
| β = IC/IB | Current Gain (BJT) | Dimensionless |
| α = IC/IE | Current Gain (CB) | Dimensionless |
| β = α/(1-α) | Relation between α and β | Dimensionless |
| IE = IB + IC | Current Relation in BJT | A |
| Av = -βRL/ri | Voltage Gain | Dimensionless |
| Av = -gmRL | Voltage Gain (FET) | Dimensionless |
| Ai = β | Current Gain | Dimensionless |
| Ap = Av × Ai | Power Gain | Dimensionless |
| Ri = βre | Input Resistance | Ω |
| R₀ = RC | Output Resistance | Ω |
| f₀ = 1/(2π√LC) | Resonant Frequency | Hz |
| fc = 1/(2πRC) | Cut-off Frequency | Hz |
| BW = f₂ – f₁ | Bandwidth | Hz |
| Q = f₀/BW | Quality Factor | Dimensionless |
| gm = ΔIC/ΔVBE | Transconductance | S |
| rd = 1/gm | Dynamic Resistance | Ω |
| VBE = 0.7 V | Base-Emitter Voltage (Si) | V |
| VBE = 0.3 V | Base-Emitter Voltage (Ge) | V |
| ni = √(NC NV)e^(-Eg/2kT) | Intrinsic Carrier Concentration | m⁻³ |
| σ = nμₑe + pμₕe | Conductivity | S/m |
| VT = kT/q | Thermal Voltage | V |
| G = 1/R | Conductance | S |
Constants:
- k = 1.38 × 10⁻²³ J/K (Boltzmann constant)
- q = 1.6 × 10⁻¹⁹ C (Electronic charge)
- T = 300 K (Room temperature)
Also Check: Toughest and Easiest Chapters in CBSE Class 12 Chemistry
Tips to Memorise Physics Formulas for Class 12 Students
Memorising physics formulas for class 12 doesn’t have to be a nightmare! Here are some proven strategies that actually work for mastering physics formulas:
• Create flashcards – Write the formula on one side and its application on the other. Review them during breaks or whilst travelling to reinforce your memory of physics formulas for class 12.
• Practice derivations – Understanding how formulas are derived helps you remember them better and builds deeper understanding of fundamental physics formulas for class 12.
• Use mnemonics – Create memorable phrases or acronyms. For example, “V = IR” can be remembered as “Voltage Is Resistance times Current.”
• Apply formulas immediately – Solve problems right after learning a formula. This reinforces memory through practice with physics formulas for class 12.
• Group similar formulas – Study related formulas together (like all the lens formulas or all the AC formulas) to understand patterns in physics formulas for class 12.
• Write them repeatedly – The old-fashioned method of writing formulas multiple times still works wonders for muscle memory.
• Make formula sheets – Create concise summary sheets for each chapter and stick them where you’ll see them often.
Also Check: Toughest and Easiest Chapters in CBSE Class 12 Physics
Conclusion
Mastering physics formulas for class 12 is your gateway to exam success and a deeper understanding of the physical world around you. Remember that physics formulas for class 12 aren’t just equations to memorise, they’re the language physics uses to describe natural phenomena. Regular practice with these physics formulas for class 12 will not only help you score better marks but also develop logical thinking skills that benefit you beyond academics. Keep this comprehensive guide handy, practice consistently with these physics formulas for class 12, and watch your physics performance soar to new heights!
FAQs
How many formulas should I memorise for Class 12 Physics?
Focus on the essential formulas from each chapter—approximately 100-120 key formulas. Quality over quantity is important; understand the derivation and application of each formula.
What’s the best way to avoid mixing up similar formulas?
Create comparison charts, practice derivations, and solve plenty of problems. Understanding the physical meaning behind each formula helps prevent confusion.
Should I memorise the values of all physical constants?
Learn the most commonly used constants like c, h, k, μ₀, ε₀, and their approximate values. Most exams provide a formula sheet with constants.
How can I remember which formula to use in word problems?
Practice identifying keywords in problems, understand the physical situation described, and create a mental map linking problem types to relevant formulas.
