University Physics Study Notes

UNITS AND MEASUREMENT

• Force: SI unit is Newton ($N$); $1\,N = 1\,kg \cdot ms^{-2}$.

• Work and Energy: SI unit is Joule ($J$). Commercial unit of energy is Kilowatt-hour ($kWh$); $1\,kWh = 3.6 \times 10^{6}\,J$.

• Power: SI unit is Watt ($W$). Industrial unit is Horsepower ($746\,W = 1\,HP$).

• Pressure: SI unit is Pascal ($Pa$) or $N/m^{2}$.

• Light-year: Unit of distance ($9.461 \times 10^{12}\,km$).

• Resistivity: SI unit is Ohm-meter ($\Omega m$).

• Luminous Intensity: SI unit is Candela ($cd$).

MECHANICS

• Weight: A force ($W = mg$); SI unit is Newton.

• Momentum: Vector quantity ($p = mv$); unit is $kg \cdot ms^{-1}$.

• Acceleration ($a$): Rate of change of velocity ($a = \frac{v-u}{t}$).

• Newton’s Laws:

  • 1st: Law of Inertia.

  • 2nd: $F = ma$.

  • 3rd: Action-Reaction (e.g., rocket launching).

• Gravity: $g = 9.8\,ms^{-2}$. Value of $g$ is maximum at poles, minimum at the equator, and zero at the Earth's center.

• Centripetal Force: Acts toward the center in circular motion ($F = \frac{mv^{2}}{r}$).

PROPERTIES OF MATTER

• Density: $\rho = \frac{m}{V}$. Water is densest at $4^{\circ}C$ ($277\,K$).

• Archimedes’ Principle: Buoyant force equals the weight of fluid displaced.

• Surface Tension: Tendency of liquid to minimize surface area (reason for spherical drops).

HEAT AND THERMODYNAMICS

• Temperature Scales: $K = ^{\circ}C + 273.15$. Absolute zero is $0\,K$ ($-273.15^{\circ}C$).

• Heat Transfer: Conduction (solids), Convection (fluids), Radiation (vacuum).

• Thermodynamic Zeroth Law: Defines thermal equilibrium.

• 1st Law: Conservation of energy.

SOUND AND WAVES

• Sound Waves: Longitudinal mechanical waves; cannot travel in a vacuum.

• Audible Range: $20\,Hz$ to $20,000\,Hz$.

• Wave Equation: $v = f\lambda$.

• Echo: Requires a minimum distance of $17.2\,m$; sound persists for $0.1\,s$.

• SONAR: Uses ultrasound for underwater distance/speed measurement.

OPTICS

• Snell’s Law/Refraction: Bending of light between mediums. Speed of light ($c \approx 3 \times 10^{8}\,ms^{-1}$).

• Mirrors:

  • Concave: Converging; used in headlights and by dentists.

  • Convex: Diverging; used for vehicle rear-view mirrors.

• Human Eye Defects:

  • Myopia: Near-sightedness; corrected by concave lens.

  • Hypermetropia: Far-sightedness; corrected by convex lens.

• Dispersion: Splitting white light into VIBGYOR colors using a prism.

ELECTRICITY AND MAGNETISM

• Ohm’s Law: $V = IR$.

• Resistors:

  • Series: $R<em>{s} = R</em>{1} + R_{2}$.

  • Parallel: $\frac{1}{R<em>{p}} = \frac{1}{R</em>{1}} + \frac{1}{R_{2}}$.

• Electric Power: $P = VI = I^{2}R = \frac{V^{2}}{R}$.

• Electromagnetic Induction: Generation of current via relative motion (Michael Faraday).

• Transformer: Changes voltage levels based on mutual induction.

NUCLEAR PHYSICS AND INVENTIONS

• Fission: Heavy nucleus splits (Nuclear reactors).

• Fusion: Light nuclei combine (energy source of the Sun).

• India's First Reactor: Apsara ($1956$).

• Key Inventors: Einstein (Relativity, $E=mc^{2}$), Röntgen (X-rays), Graham Bell (Telephone), Edison (Bulb).