| UPSC Physics Optional Syllabus 2025 For Paper I |
| Topics |
Subtopics |
| 1. Mechanics of Particles and Other, Special Relativity |
- 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 and laboratory reference frames.
- 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 triatomic molecules; Precessional motion; top, gyroscope.
- 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.
- Special Relativity: Michelson-Morely 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.
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| 2. Waves and Optics |
- 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.
- Geometrial Optics: Laws of reflection and refraction from Fermat’s principle; Matrix method in paraxial optic-thin lens formula, nodal planes, system of two thin lenses, chromatic and spherical aberrations.
- Interference: Interference of light-Young’s experiment, Newton’s rings, interference by thin films, Michelson interferometer; Multiple beam interference, and Fabry Perot interferometer.
- 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.
- Polarisation and Modern Optics : Production and detection of linearly and circularly polarized light; Double refraction, quarter wave plate; Optical activity; Principles of fibre optics, attenuation; Pulse dispersion in step index and parabolic index fibres; 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.
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| 3. Electricity and Magnetism |
- Electrostatics and Magnetostatics: Laplace and Poisson equations in electrostatics and their applications; Energy of a system of charges, multipole 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, polarisation.
Solutions to boundary value problems-conducting and dielectric spheres in a uniform electric field; Magnetic shell, uniformly magnetised sphere; Ferromagnetic materials, hysteresis, energy loss.
- Current Electricity: Kirchhoff's laws and their applications. Biot-Savart law, Ampere’s law, Faraday’s law, Lenz’ law. Selfand mutual- inductances; Mean and rms values in AC circuits; DC and AC circuits with R, L and C components; Series and parallel resonance; Quality factor; Principle of transformer.
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| 4. Electromagnetic Waves and Blackbody Radiation |
- Displacement current and Maxwell’s equations; Wave equations in vacuum, Poynting 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; Blackbody radiation and Planck ’s radiation law- Stefan-Boltzmann law, Wien’s displacement law and Rayleigh-Jeans law.
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| 5. Thermal and Statistical Physics |
- 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; Van der Waals equation of state of a real gas, critical constants; Maxwell-Boltzmann distribution of molecular velocities, transport phenomena, equipartition and virial theorems; Dulong-Petit, Einstein, and Debye’s theories of specific heat of solids; Maxwell relations and application; Clausius-Clapeyron equation. Adiabatic demagnetisation, Joule-Kelvin effect, and liquefaction of gases.
- Statistical Physics: Macro and micro states, statistical distributions, Maxwell-Boltzmann, Bose-Einstein, and Fermi-Dirac Distributions, applications to the specific heat of gases and blackbody radiation; Concept of negative temperatures.
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