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A–Z
All A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Quantum & Atomic Physics

Wave Function

A complex-valued mathematical function containing all the physical information about the state of an isolated quantum mechanical system.

ψ(x, t) = A e^(i (k x - ω t)) m^(-3/2) (in 3D space)
Waves, Oscillations & Acoustics

Wave Number

A spatial frequency measure expressing the number of radians or wave cycles per unit distance.

k = 2π / λ rad/m (or m⁻¹)
Waves, Oscillations & Acoustics

Wave Packet

A short localized burst or envelope of wave energy formed by the superposition of multiple waves with slightly different frequencies.

Δx Δk ≥ ½ m
Quantum & Atomic Physics

Wave-Particle Duality

The fundamental quantum mechanical principle stating that every subatomic entity exhibits both wave-like and particle-like behavior…

E = h ν, p = h / λ Dimensionless Concept
Waves, Oscillations & Acoustics

Waveform

The visual shape or graph of a signal or wave as a function of time or spatial position.

y = f(x - v t) N/A
Nuclear & Particle Physics

Weak Nuclear Force

The short-range fundamental interaction responsible for flavor-changing particle transformations, neutrino interactions, and radioactive…

Mediated by massive W⁺, W⁻, and Z⁰ gauge bosons Range ~ 10⁻¹⁸ m
Biophysics & Medical Physics

Weber-Fechner Law

A psychophysical law stating that human subjective sensory perception is proportional to the logarithm of the physical stimulus intensity.

p = k ln(S / S₀) (Perceived Sensation = k ln(Stimulus Intensity)) Psychophysical Scale (e.g. dB, Stellar Magnitude)
Foundations of Physics

Weight

The downward gravitational force exerted on an object's mass by a surrounding gravitational field.

W = m g N
Electromagnetism & Electronics

Wheatstone Bridge

An electrical bridge network consisting of four resistor arms used to measure an unknown electrical resistance with high precision.

R_x = R₃ (R₂ / R₁) (when balanced: I_galvanometer = 0) Ω (Ohms)
Plasma Physics

Whistler Waves

A right-hand circularly polarized electromagnetic wave mode propagating along magnetic field lines in a magnetized plasma below electron…

v_phase = c √(ω ω_ce) / ω_pe (For ω ≪ ω_ce) Audio Frequency Pitch Glissando (kHz)
Astrophysics, Cosmology & Relativity

White Dwarf

The dense stellar remnant remaining after a low-to-medium mass star exhausts its core nuclear fuel and sheds its outer layers.

P_deg ∝ ρ^(5/3) (Electron Degeneracy Pressure) M_☉ (Mass) or R_Earth (Radius)
Thermodynamics & Statistical Physics

Wien's Displacement Law

The physical law stating that peak emission wavelength of a blackbody spectrum is inversely proportional to its absolute temperature.

λ_max T = b ≈ 2.89777 × 10⁻³ m·K m·K
Classical Mechanics

Work

The scalar energy transferred to or from an object by a force acting through a displacement.

W = F · d = |F| |d| cos θ J (N·m)
Condensed Matter & Materials Physics

Work Hardening

The strengthening of a metal by plastic deformation, caused by dislocation multiplication and entanglement obstructing further slip.

σ_y = σ₀ + α G b √ρ_dislocation (Taylor Relation) MPa (Increased Yield Strength)
Classical Mechanics

Work-Energy Theorem

The principle stating that net work done by all forces acting on an object equals the net change in its kinetic energy.

W_net = ΔKE = ½ m vf² - ½ m vi² J
Astrophysics, Cosmology & Relativity

Wormhole

A hypothetical topological feature of spacetime creating a shortcut connecting two separate points in space and time.

ds² = -c² dt² + dl² + (r₀² + l²) (dθ² + sin²θ dφ²) Einstein-Rosen Bridge Topology
Biophysics & Medical Physics

X-Ray Crystallography in Biology

An experimental biophysical technique determining the 3D atomic structure of biological macromolecules from X-ray diffraction patterns of…

n λ = 2 d sin θ (Bragg's Law for Macromolecules) Å or nm (Structural Resolution)
Biophysics & Medical Physics

X-ray Imaging

A diagnostic medical imaging modality using differential photoelectric attenuation of X-rays passing through human tissue to form 2D…

I(x) = I₀ e^(-μ x) (Beer-Lambert Attenuation) keV (Photon Energy) & μ (Attenuation Coefficient in cm⁻¹)
Optics

Young's Double Slit Experiment

The classic experiment demonstrating wave-particle duality and wave nature of light via interference fringes produced by coherent light…

y_m = m λ D / d (Bright), y_m = (m + ½) λ D / d (Dark) m
Condensed Matter & Materials Physics

Young's Modulus

A mechanical property measuring the tensile or compressive stiffness of a solid material in its linear elastic deformation regime.

E = σ / ε = (F / A) / (ΔL / L₀) Pa or GPa (Gigapascals)
Plasma Physics

Z-Pinch

A plasma confinement geometry where an axial electric current passed through a plasma column generates a self-pinching azimuthal magnetic…

Bennett Relation: I² = (8 π / μ₀) N k_B (T_e + T_i) MA (Mega-amperes Current)
Quantum & Atomic Physics

Zeeman Effect

The splitting of atomic spectral lines into multiple closely spaced components in the presence of an external static magnetic field.

ΔE = g_L μ_B m_j B eV (Energy Shift)
Electromagnetism & Electronics

Zener Diode

A heavily doped silicon p-n junction diode designed to operate safely in reverse breakdown mode to maintain a precise reference voltage.

V_out = V_Z (constant in reverse breakdown) V (Volts)
Foundations of Physics

Zero Error

A systematic error that occurs when a measuring instrument displays a non-zero reading when the actual quantity being measured is zero.

True Value = Observed Value - Zero Error Various