The UPSC includes Physics as one of the optional subjects among the 48 subjects available for candidates to choose from. The syllabus for Physics in the UPSC exam is highly specialized and covers a wide range of topics, including classical mechanics, electromagnetism, quantum mechanics, thermodynamics, and modern physics.

Candidates who opt for Physics as their optional subject will have to appear for two papers, each carrying 250 marks, resulting in a total of 500 marks for this subject. These optional papers form an important part of the UPSC Mains Examination, which is conducted after the IAS Preliminary exam. While Physics may not be as commonly chosen as some other subjects for the IAS Mains exam, candidates with a graduation degree or a strong background in Physics have the opportunity to select it as their preferred optional subject.

## Physics Optional Syllabus: **Paper-1**

**(a) Mechanics of Particles:**

- Laws of motion; conservation of energy and momentum, applications to rotating frames, centripetal and Coriolis accelerations; Motion under a central force; Conservation of angular momentum, Kepler’s laws; Fields and potentials; Gravitational field and potential due to spherical bodies, Gauss and Poisson equations, gravitational self-energy; Two-body problem; Reduced mass; Rutherford scattering; Centre of mass a laboratory reference frames.

**(b) Mechanics of Rigid Bodies:**

- System of particles; Centre of mass, angular momentum, equations of motion; Conservation theorems for energy, momentum, and angular momentum; Elastic and inelastic collisions; Rigid body; Degrees of freedom, Euler’s theorem, angular velocity, angular momentum, moments of inertia, theorems of parallel and perpendicular axes, equation of motion for rotation; Molecular rotations (as rigid bodies); Di and tri-atomic molecules; Processional motion; top, gyroscope.

**(c) Mechanics of Continuous Media:**

- Elasticity, Hooke’s law and elastic constants of isotropic solids and their inter-relation; Streamline (Laminar) flow, viscosity, Poiseuille’s equation, Bernoulli’s equation, Stokes’ law and applications.

**(d) Special Relativity:**

- Michelson-Morley experiment and its implications; Lorentz transformations-length contraction, time dilation, the addition of relativistic velocities, aberration and Doppler effect, mass-energy relation, simple applications to a decay process; Four-dimensional momentum vector; Covariance of equations of physics.

## 2. Waves and Optics:

**(a) Waves:**

- Simple harmonic motion, damped oscillation, forced oscillation and resonance; Beats; Stationary waves in a string; Pulses and wave packets; Phase and group velocities; Reflection and Refraction from Huygens’ principle.

**(b) Geometrical Optics:**

- Laws of reflection and refraction from Fermat’s principle; Matrix method in paraxial optics-thin lens formula, nodal planes, system of two thin lenses, chromatic and spherical aberrations.

**(c) Interference:**

- Interference of light’s experiment, Newton’s rings, interference by thin films, Michelson interferometer; Multiple beam interference, and Fabry-Perot interferometer.

**(d) Diffraction:**

- Fraunhofer diffraction-single slit, double slit, diffraction grating, resolving power; Diffraction by a circular aperture and the Airy pattern; Fresnel diffraction: half-period zones and zone plates, circular aperture.

**(e) Polarization and Modern Optics:**

- Production and detection of linearly and circularly polarized light; Double refraction, quarter-wave plate; Optical activity; Principles of fiber optics, attenuation; Pulse dispersion in step-index and parabolic index fibers; Material dispersion, single-mode fibers; Lasers-Einstein A and B coefficients; Ruby and He-Ne lasers; Characteristics of laser light-spatial and temporal coherence; Focusing of laser beams; Three-level scheme for laser operation; Holography and simple applications.

## 3. Electricity and Magnetism:

**(a) Electrostatics and Magnetostatics:**

- Laplace and Poisson equations in electrostatics and their applications; Energy of a system of charges, multiple expansion of scalar potential; Method of images and its applications; Potential and field due to a dipole, force and torque on a dipole in an external field; Dielectrics, polarization; Solutions to boundary-value problems-conducting and dielectric spheres in a uniform electric field; Magnetic shell, uniformly magnetized sphere; Ferromagnetic materials, hysteresis, energy loss.

**(b) Current Electricity:**

- Kirchhoff’s laws and their applications; Biot-Savart law, Ampere’s law, Faraday’s law, Lenz’s law; Self-and mutual-inductances; Mean and r m s values in AC circuits; DC and AC circuits with R, L, and C components; Series and parallel resonances; Quality factor; Principle of the transformer.

## 4. Electromagnetic Waves and Blackbody Radiation:

- Displacement current and Maxwell’s equations; Wave equations in vacuum, Pointing theorem; Vector and scalar potentials; Electromagnetic field tensor, covariance of Maxwell’s equations; Wave equations in isotropic dielectrics, reflection and refraction at the boundary of two dielectrics; Fresnel’s relations; Total internal reflection; Normal and anomalous dispersion; Rayleigh scattering; Black body radiation and Planck’s radiation law, Stefan – Boltzmann law, Wien’s displacement law and Rayleigh-Jeans’ law.

## 5. Thermal and Statistical Physics:

**(a) Thermodynamics:**

- Laws of thermodynamics, reversible and irreversible processes, entropy; Isothermal, adiabatic, isobaric, isochoric processes and entropy changes; Otto and Diesel engines, Gibbs’ phase rule and chemical potential; Vander Waals equation of state of a real gas, critical constants; Maxwell-Boltzman distribution of molecular velocities, transport phenomena, equipartition, and virial theorems; Dulong-Pet it, Einstein, and Debye’s theories of specific heat of solids; Maxwell relations and applications; Clausius- Clapeyron equation; Adiabatic de-magnetization, Joule-Kelvin effect and liquefaction of gases.

**(b) Statistical Physics:**

- Macro and microstates, statistical distributions, Maxwell-Boltzmann, Bose-Einstein, and Fermi-Dirac distributions, applications to the specific heat of gases and black body radiation; Concept of negative temperatures.

## Physics Optional Syllabus: **Paper-2**

### 1. Quantum Mechanics:

- Wave-particle duality; Schroedinger equation and expectation values; Uncertainty principle; Solutions of the one-dimensional Schroedinger equation for a free particle (Gaussian wave-packet), particle in a box, particle in a finite well, linear harmonic oscillator; Reflection and transmission by a step potential and by a rectangular barrier; Particle in a three-dimensional box, the density of states, free electron theory of metals; Angular momentum; Hydrogen atom; Spin half particles, properties of Pauli spin matrices.

### 2. Atomic and Molecular Physics:

- Stern-Gerlach experiment, electron spin, fine structure of hydrogen atom; L-S coupling, J-J coupling; Spectroscopic notation of atomic states; Zeeman effect; Frank Condon principle and applications; Elementary theory of rotational, vibrational and electronic spectra of diatomic molecules; Raman effect and molecular structure; Laser Raman spectroscopy; Importance of neutral hydrogen atom, molecular hydrogen and molecular hydrogen ion in astronomy; Fluorescence and Phosphorescence; Elementary theory and applications of NMR and EPR; Elementary ideas about Lamb shift and its significance.

### 3. Nuclear and Particle Physics:

- Basic nuclear properties, binding energy, angular momentum, parity, magnetic moment; Semi-empirical mass formula and applications, mass parabolas; Ground state of deuteron, magnetic moment and non-central forces; Meson theory of nuclear forces; Salient features of nuclear forces; Shell model of the nucleus – successes and limitations; Violation of parity in beta decay; Gamma decay and internal conversion; Elementary ideas about Mossbauer spectroscopy; Q-value of nuclear reactions; Nuclear fission and fusion, energy production in stars; Nuclear reactors.
- Classification of elementary particles and their interactions; Conservation laws; Quark structure of hadrons; Field quanta of electroweak and strong interactions; Elementary ideas about unification of forces; Physics of neutrinos.

### 4. Solid State Physics, Devices and Electronics:

- Crystalline and amorphous structure of matter; Different crystal systems, space groups; Methods of determination of crystal structure; X-ray diffraction, scanning and transmission electron microcopies; Band theory of solids – conductors, insulators and semiconductors; Thermal properties of solids, specific heat, Debye theory; Magnetism: para and ferromagnetism; Elements of superconductivity, Meissner effect, Josephson junctions and applications; Elementary ideas about high-temperature superconductivity.
- Intrinsic and extrinsic semiconductors; pn-p and n-p-n transistors; Amplifiers and oscillators; Op-amps; FET, JFET, and MOSFET; Digital electronics-Boolean identities, De Morgan’s laws, logic gates, and truth tables; Simple logic circuits; Thermostats, solar cells; Fundamentals of microprocessors and digital computers.

## Frequently Asked Questions (FAQs)

**1. Question: What are the key topics covered in the Physics optional syllabus for competitive exams?**

Answer: The Physics optional syllabus for competitive exams typically covers a wide range of topics. Some of the key areas include classical mechanics, quantum mechanics, electromagnetism, thermodynamics, statistical mechanics, and mathematical methods in physics. Additionally, special emphasis is often given to areas like solid-state physics, nuclear physics, and electronics. Candidates should thoroughly study both theoretical concepts and mathematical applications in these domains.

**2. Question: How can candidates effectively prepare for the numerical and mathematical aspects of the Physics optional syllabus?**

Answer: To excel in the numerical and mathematical aspects of the Physics optional syllabus, candidates should focus on a two-pronged approach. Firstly, they should build a strong conceptual understanding of the underlying principles. Secondly, regular practice is crucial. Solving a variety of numerical problems and mathematical exercises will enhance problem-solving skills and ensure familiarity with the application of theoretical concepts. Candidates are advised to use standard textbooks and reference materials to practice a diverse set of problems.

**3. Question: Are there any specific strategies for time management while preparing for the Physics optional paper?**

Answer: Time management is critical when preparing for the Physics optional paper. Candidates should create a well-structured study plan that allocates sufficient time to cover all the topics in the syllabus. It’s advisable to prioritize topics based on their weightage in previous exam papers. Regular revision is essential to reinforce concepts and formulas. Additionally, solving previous years’ question papers under timed conditions helps candidates gauge their preparedness and improve time efficiency during the actual exam. Balancing theory and problem-solving practice is key to effective time management.

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