Browse All 842 Physics Terms A–Z

Stokes' Theorem Mathematical & Computational Physics Vector Line/Surface Integral Equality A fundamental vector calculus theorem relating the surface integral of the curl of a vector field over an open surface S to the line integral of the field around its boundary curve ∂S. ∮_(∂S) F · dr = ∬_S (∇ × F) · dA

Stratosphere Geophysics & Environmental Physics km (Altitude ~12 to 50 km) The second major layer of Earth's atmosphere, extending from the tropopause (~12 km) up to the stratopause (~50 km), containing the protective ozone layer. dT / dz > 0 (Temperature Inversion via O₃ Absorption)

Strong Nuclear Force Nuclear & Particle Physics N (Newtons) The powerful fundamental interaction that binds quarks together into hadrons and holds protons and neutrons together inside the atomic nucleus. F_strong ≫ F_EM (Range r ≤ 1–3 fm)

Sublimation Thermodynamics & Statistical Physics J/kg or J/mol The direct phase transition of a substance from solid to gas state without passing through an intermediate liquid phase. ΔH_sub = ΔH_fus + ΔH_vap

Superalloys Condensed Matter & Materials Physics High Temperature Strength (MPa at >800 °C) High-performance metallic alloys engineered to maintain exceptional mechanical strength, creep resistance, and oxidation resistance at high operational temperatures. γ' Phase Precipitation: Ni₃(Al, Ti)

Superconductivity Condensed Matter & Materials Physics K (Critical Temperature T_c) A macroscopic quantum state of matter where certain materials exhibit exactly zero electrical DC resistance and complete expulsion of magnetic fields below a critical temperature T_c. R = 0 (for T < T_c), B = 0 (Meissner expulsion)

Superfluidity Condensed Matter & Materials Physics K (Lambda Transition Temperature) A macroscopic quantum state of matter where a fluid flows with exactly zero viscosity and zero kinetic entropy. Viscosity η = 0 (Below Lambda point T_λ = 2.17 K)

Supernova Astrophysics, Cosmology & Relativity 10⁴⁴ Joules (Energy Output) A catastrophic stellar explosion marking the death of a star, briefly outshining an entire galaxy and dispersing heavy elements into space. Type Ia: M = M_Ch; Type II: Core Collapse M > 8 M_☉

Surface Energy Condensed Matter & Materials Physics J/m² or N/m The excess thermodynamic energy at the surface of a material relative to its interior bulk, caused by disrupted, incomplete atomic bonds. γ = dW / dA

Synchrotron Nuclear & Particle Physics GeV or TeV (Beam Energy) A large ring-shaped particle accelerator in which guiding magnetic fields and accelerating RF electric fields increase synchronously as particles gain relativistic energy. B(t) ∝ p(t), RF Frequency Synchronized to Beam Speed

Systematic Error Foundations of Physics Various A consistent, repeatable error in experimental measurements that skews data in the same direction from the true value. Offset = Mean Measured - True Value

Tau Lepton Nuclear & Particle Physics MeV/c² (Mass Energy) The third-generation elementary charged lepton, with a mass approximately 3,477 times heavier than an electron. m_τ ≈ 1776.8 MeV/c², τ_τ ≈ 2.9 × 10⁻¹³ s, Spin = ½

Taylor Series Mathematical & Computational Physics Infinite Polynomial Expansion An infinite polynomial series representation of a smooth function expressed in terms of its higher-order derivatives evaluated at a single point a. f(x) = ∑_(n=0)^(∞) (f^(n)(a) / n!) (x - a)^n

Temperature Thermodynamics & Statistical Physics K (°C, °F) A macroscopic scalar measure of the average translational kinetic energy of constituent particles in a physical system. 1 / T = (∂S / ∂U)_V, E_avg = (3/2) kB T

Tension Classical Mechanics N The pulling force transmitted axially through a string, rope, cable, or structural member. T = m g + m a

Tensor Mathematical & Computational Physics Geometric Multilinear Object A multilinear geometric object describing linear relationships between algebraic vectors, tensors, and scalars independent of coordinate choice. T'^ij = (∂x'^i / ∂x^k) (∂x'^j / ∂x^l) T^kl

Terminal Velocity Classical Mechanics m/s The constant maximum speed attained by a falling body when upward aerodynamic drag equals downward gravitational force. v_t = √(2 m g / (ρ A Cd))

Terrestrial Telescope Optics Dimensionless (×) A refracting telescope incorporating an additional erecting lens system between objective and eyepiece to yield an upright image for ground observation. M = f_obj / f_eye, Tube Length L = f_obj + 4 f_erect + f_eye

Thermal Conduction Thermodynamics & Statistical Physics W/m² (k in W/(m·K)) The transfer of thermal energy through a stationary medium via microscopic particle collisions and free electron movement without bulk fluid movement. q = -k A (dT/dx) (Fourier's Law)

Thermal Convection Thermodynamics & Statistical Physics W (h in W/(m²·K)) The transfer of heat energy between a solid surface and an adjacent moving fluid, driven by bulk fluid motion. q = h A (T_surface - T_fluid) (Newton's Law of Cooling)

Thermal Efficiency Thermodynamics & Statistical Physics Dimensionless (%) The dimensionless ratio of net mechanical work produced by a heat engine to total thermal energy input supplied. η = W_net / Q_input = 1 - (Q_out / Q_in)

Thermal Radiation Thermodynamics & Statistical Physics W The emission of electromagnetic energy from matter due to thermal agitation of its charged constituent particles. P = ε σ A T⁴ (Stefan-Boltzmann Law)

Thermal Stress Thermodynamics & Statistical Physics Pa (N/m²) Mechanical stress developed within a material when thermal expansion or contraction is constrained by rigid boundaries. σ = E α ΔT

Thermal vs Non-Thermal Plasmas Plasma Physics Kelvin or eV The classification of plasmas based on thermodynamic equilibrium between electron temperature T_e and heavy ion/gas temperature T_i. Thermal: T_e ≈ T_i ≈ T_gas; Non-Thermal: T_e ≫ T_i ≈ T_gas

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