IFoS Physics Optional Syllabus 2026: Paper I & II Topics, Exam Pattern, PDF

The IFoS Physics Optional Syllabus 2026 helps you understand all the topics included in the Physics optional subject for the Indian Forest Service (Main) Examination. It covers Classical Mechanics, Optics, Electricity and Magnetism, Thermodynamics, Quantum Mechanics, Nuclear Physics, Solid State Physics, Electronics, and other important areas of physics.

Before starting preparation, you should go through the complete syllabus to understand the paper structure, identify important topics, and plan your study schedule effectively. The syllabus is prescribed by the Union Public Service Commission (UPSC) for the IFoS Main Examination.

IFoS Physics Optional Syllabus 2026 Overview

Before studying the detailed syllabus, check the important details below.

IAS coaching

IFoS Physics Optional Exam Pattern 2026 

The IFoS Physics Optional Exam Pattern consists of two descriptive papers. Each paper carries 200 marks and is conducted for 3 hours. Candidates must write their answers in English. The optional subject contributes significantly to the final merit in the IFoS Main Examination. 

IFoS Physics Optional Syllabus 2026 – Paper I 

The IFoS Physics Optional Syllabus 2026 Paper I is divided into two sections.

Section A

1. Mechanics

• Centre of mass and laboratory coordinates
• Conservation of linear and angular momentum
• Rocket equation
• Rutherford scattering
• Galilean transformation
• Inertial and non-inertial frames
• Rotating frames
• Centrifugal and Coriolis forces
• Foucault pendulum

System of Particles

• Constraints and degrees of freedom
• Generalized coordinates and moments
• Lagrange’s equations
• Hamilton’s principle
• Cyclic coordinates
• Linear harmonic oscillator
• Simple pendulum
• Central force problems

Rigid Body Dynamics

• Eulerian angles
• Inertia tensor
• Principal moments of inertia
• Euler’s equations
• Force-free motion
• Gyroscope

Explore UPSC Foundation Courses

Explore UPSC Foundation Courses

2. Special Relativity, Waves, and Geometrical Optics

Special Relativity

• Michelson-Morley experiment
• Lorentz transformation
• Length contraction
• Time dilation
• Velocity addition
• Doppler effect
• Mass-energy relation
• Minkowski diagram
• Four-dimensional momentum
• Covariance of physical laws

Waves

• Simple harmonic motion
• Damped and forced oscillations
• Resonance
• Beats
• Stationary waves
• Wave packets
• Phase and group velocity
• Reflection and refraction

Geometrical Optics

• Fermat’s principle
• Reflection and refraction
• Matrix method
• Thin lens formula
• Nodal planes
• Lens combinations
• Chromatic aberration
• Spherical aberration

3. Physical Optics

Interference

• Young’s double slit experiment
• Newton’s rings
• Thin film interference
• Michelson interferometer
• Fabry-Perot interferometer
• Holography

Diffraction

• Fraunhofer diffraction
• Fresnel diffraction
• Diffraction grating
• Zone plates
• Cornu’s spiral
• Airy pattern
• Circular aperture diffraction

Polarisation and Modern Optics

• Polarised light
• Double refraction
• Quarter-wave plate
• Optical activity
• Fibre optics
• Dispersion
• Lasers
• Ruby laser
• He-Ne laser
• Laser coherence
• Three-level laser system

UPSC Online Coaching

Section B

4. Electricity and Magnetism

Electrostatics and Magnetostatics

• Laplace and Poisson equations
• Multipole expansion
• Method of images
• Electric dipole
• Dielectrics
• Polarisation
• Conducting and dielectric spheres
• Magnetic shell
• Ferromagnetism
• Hysteresis

Current Electricity

• Kirchhoff’s laws
• Biot-Savart law
• Ampere’s law
• Faraday’s law
• Lenz’s law
• Self and mutual inductance
• AC circuits
• LR, CR and LCR circuits
• Resonance
• Transformer

5. Electromagnetic Theory and Black Body Radiation

Electromagnetic Theory

• Maxwell’s equations
• Displacement current
• Wave equations
• Poynting theorem
• Scalar and vector potentials
• Gauge invariance
• Lorentz and Coulomb gauges
• Electromagnetic field tensor
• Fresnel relations
• Dispersion
• Rayleigh scattering

Black Body Radiation

• Planck radiation law
• Stefan-Boltzmann law
• Wien’s displacement law
• Rayleigh-Jeans law
• Planck units

Explore UPSC Prarambh Course

6. Thermal and Statistical Physics

Thermodynamics

• Laws of thermodynamics
• Entropy
• Reversible and irreversible processes
• Otto and Diesel engines
• Gibbs phase rule
• Chemical potential
• Van der Waals equation
• Maxwell-Boltzmann distribution
• Equipartition theorem
• Specific heat theories
• Maxwell relations
• Clausius-Clapeyron equation
• Joule-Kelvin effect
• Liquefaction of gases

Statistical Physics

• Saha ionization formula
• Bose-Einstein condensation
• Ideal Fermi gas
• Chandrasekhar limit
• Neutron stars
• Pulsars
• Brownian motion
• Diffusion
• Negative temperature

IFoS Physics Optional Syllabus 2026 Paper II

The IFoS Physics Optional Syllabus 2026 Paper II is divided into Section A and Section B. It focuses on Quantum Mechanics, Atomic Physics, Molecular Physics, Nuclear Physics, Particle Physics, Solid State Physics, and Electronics. 

Section A

1. Quantum Mechanics I

• Wave-particle duality
• Schrödinger equation
• Expectation values
• Uncertainty principle
• Particle in a box
• Finite potential well
• Harmonic oscillator
• Potential barrier
• WKB approximation
• Alpha decay

2. Quantum Mechanics II and Atomic Physics

Quantum Mechanics II

• Three-dimensional box
• Density of states
• Free electron theory
• Angular momentum
• Hydrogen atom
• Spin-half particles
• Pauli spin matrices

Atomic Physics

• Stern-Gerlach experiment
• Electron spin
• Fine structure
• LS coupling
• JJ coupling
• Spectroscopic notation
• Zeeman effect
• Frank-Condon principle

Click to Know UPSC Coaching Centres in India

3. Molecular Physics

• Rotational spectra
• Vibrational spectra
• Electronic spectra
• Raman effect
• Laser Raman spectroscopy
• Molecular hydrogen
• Molecular hydrogen ion
• Fluorescence
• Phosphorescence
• NMR
• Lamb shift

Section B

4. Nuclear Physics

• Nuclear properties
• Binding energy
• Magnetic moment
• Semi-empirical mass formula
• Mass parabola
• Deuteron
• Nuclear forces
• Meson theory
• Shell model
• Beta decay
• Gamma decay
• Internal conversion
• Mossbauer spectroscopy
• Nuclear reactions
• Fission
• Fusion
• Nuclear reactors
• Stellar energy production

5. Particle Physics and Solid State Physics

Particle Physics

• Elementary particles
• Fundamental interactions
• Conservation laws
• Quark model
• Electroweak interaction
• Strong interaction
• Unification of forces
• Neutrino physics

Solid State Physics

• Crystal structure
• Band theory
• Conductors
• Insulators
• Semiconductors
• Superconductivity
• Meissner effect
• Josephson junction
• High-temperature superconductors

6. Electronics

• Intrinsic semiconductors
• Extrinsic semiconductors
• Bipolar junction transistors
• Amplifiers
• Oscillators
• Operational amplifiers
• FET
• JFET
• MOSFET
• Boolean algebra
• Logic gates
• Truth tables
• Logic circuits
• Thermistors
• Solar cells
• Microprocessors
• Digital computers

Click to Know UPSC Offline Courses

IFoS Physics Optional Syllabus 2026 PDF 

You should download the official IFoS Physics Optional Syllabus PDF and keep it for regular reference during your preparation. The PDF contains the complete paper-wise syllabus prescribed by UPSC and helps you track every topic while planning your studies and revision. 

IFoS Physics Optional Syllabus PDF

Preparation Tips for IFoS Physics Optional 2026 

• The IFoS Physics Optional Syllabus 2026 covers both classical and modern physics, so divide your preparation into manageable sections and complete one topic at a time.
• Revise each section thoroughly before moving to the next to strengthen retention and clarity.
• Practice numerical problems regularly to improve problem-solving speed and accuracy.
• Focus on writing clear and structured descriptive answers for theoretical topics.
• Solve previous years’ question papers to understand the exam pattern and frequently asked topics.
• Maintain a consistent revision schedule to retain concepts effectively.
• Many topics in the IFoS Physics Optional Syllabus are interconnected. Build strong conceptual understanding before moving to advanced topics. 
• Use diagrams, formulas, and short notes to simplify complex topics and aid quick revision.
• Regular answer writing practice will help improve presentation and time management in the exam.
• Candidates preparing for the next cycle can also use the same syllabus as a reference for IFoS Physics Optional 2027, unless UPSC announces any changes in the official notification.

Check Out UPSC CSE Books

Visit PW Store

DOWNLOAD PDF