Class 12 Physics Complete Derivations List (2M, 3M, 5M)

Curated by Er. VISHAL TAANK Updated for 2026 Board Exams • Based on CBSE/HP Board Syllabus
Board Exam Alert: Derivations make up roughly 30-40% of the Class 12 Physics paper. Master this exact list to secure your 5-mark and 3-mark questions instantly.

1. Electric Charges & Fields

  • 1.State Coulomb’s law, SI Unit and Dimensions of constants
    3M+2M
  • 2.Coulomb’s law in vector form (Force equality)
    2M
  • 3.Electric field intensity on the axial line of a dipole
    5M
  • 4.Electric field intensity on the equatorial line of a dipole
    5M
  • 5.Torque experienced by a dipole in uniform electric field
    3M
  • 6.Electric field intensity on the axis of a charged circular ring
    5M
  • 7.State and prove Gauss’s theorem in electrostatics
    3M
  • 8.Deduce Coulomb’s law from Gauss’s law
    3M
  • 9.Electric field intensity due to an infinitely long straight wire
    3M
  • 10.Electric field intensity due to a uniformly charged infinite plane sheet
    3M
  • 11.Electric field intensity outside a charged thin spherical shell
    3M
  • 12.Show that electric field inside a charged thin spherical shell is zero
    2M
  • 13.Electric field intensity inside a non-conducting solid sphere
    3M

2. Electrostatic Potential & Capacitance

  • 1.Electric potential at a distance r from a point charge Q
    3M
  • 2.Electric potential on the axial line of an electric dipole
    3M
  • 3.Show potential on equatorial line of a dipole is zero
    2M
  • 4.Electric potential due to short dipole at arbitrary point (r, θ)
    5M
  • 5.Relationship between electric field and potential gradient (E = -dV/dr)
    2M
  • 6.Electrostatic potential energy of a two point charge system
    4M
  • 7.Work done in rotating an electric dipole in uniform field
    3M
  • 8.Capacitance of parallel plate capacitor (air medium)
    3M
  • 9.Capacitance of parallel plate capacitor with full dielectric slab
    3M
  • 10.Capacitance with dielectric slab of thickness t < d
    5M
  • 11.Capacitance of a spherical capacitor (concentric shells)
    3M
  • 12.Formulae for equivalent capacitance (Series & Parallel)
    2M+2M
  • 13.Energy stored in a capacitor and energy density expression
    3M

3. Current Electricity

  • 1.Relation between Current (I) and Drift Velocity (vd)
    2M
  • 2.Relation between EMF (E), Terminal Voltage (V), and Internal Resistance (r)
    2M
  • 3.Expression for Drift Velocity (vd) in terms of relaxation time
    3M
  • 4.Condition for balanced Wheatstone Bridge using Kirchhoff’s Laws
    3M
  • 5.Principle of Metre Bridge and expression for unknown resistance
    4M
  • 6.Define Ohm's Law and derive microscopic Ohm's Law
    4M
  • 7.Relation of Resistance of a conductor (R = mL/ne²τA)
    4M

4. Moving Charges & Magnetism

  • 1.State Ampere’s Circuital Law and Field of an infinite straight wire
    3M
  • 2.Magnetic field at the center of a circular current loop (Biot-Savart Law)
    3M
  • 3.Torque acting on a current-carrying rectangular coil in uniform field
    3M
  • 4.Conversion of Galvanometer into Ammeter and Voltmeter
    3M
  • 5.Expression for Bohr's Magneton
    3M
  • 6.Magnetic field inside a long Solenoid
    4M
  • 7.Magnetic field on the axis of a circular current loop
    5M
  • 8.Force per unit length between two parallel current-carrying conductors
    5M
  • 9.Flux induction on the (i) Axial and (ii) Equatorial line of a bar magnet
    4M+4M

5. Electromagnetic Induction

  • 1.Energy stored in an inductor
    3M
  • 2.Motional EMF induced in a conductor moving in magnetic field
    3M
  • 3.Self-Inductance of a long solenoid
    3M
  • 4.Mutual Inductance of two coaxial solenoids
    3M
  • 5.EMF induced in a rod rotating in a uniform magnetic field
    3M

6. Alternating Current

  • 1.Resonant Frequency in a series LCR circuit
    3M
  • 2.Definition and derivation of Average value of AC
    5M
  • 3.Definition and derivation of RMS value of AC
    5M
  • 4.Average Power in an AC circuit
    5M
  • 5.Impedance and Phase Angle of Series LCR using Phasor Diagram
    5M
  • 6.Principle, working, and relations for an Ideal Transformer
    5M

7. Ray Optics

  • 1.Relation between Critical Angle (ic) and Refractive Index (μ)
    3M
  • 2.Relation between Real Depth and Apparent Depth
    2M
  • 3.Derivation of the Mirror Formula
    3M
  • 4.Relation between μ and minimum deviation (δm) for a prism
    3M
  • 5.Lens Maker’s Formula for a double convex lens
    5M
  • 6.Refraction formula at a spherical curved surface
    5M

8. Wave Optics

  • 1.Laws of Reflection/Refraction using Huygens’ Principle
    4M
  • 2.Expression for Fringe Width in Young’s Double Slit Experiment (YDSE)
    5M
  • 3.Diffraction at a single slit: Secondary maxima and minima
    5M

9. Modern Physics

  • 1.Derivation of De-Broglie Wavelength
    2M
  • 2.Bohr’s Model: Velocity and Radius of electron in nth orbit
    3M
  • 3.Total energy of an electron in the nth orbit
    3M

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