Physics
Articles about matter, energy, forces and physical laws.
Interpretations of quantum mechanics
Inverse-square law
Ionizing radiation
Ionizing radiation: nature, types, sources, effects and uses
Iron filings
Island of stability
Jerk
Joule
Joule (unit of energy)
Joule per mole
Joule per mole (J·mol⁻¹): unit of energy per amount of substance
Joule's laws
Joule's laws: electrical heating and the thermodynamics of ideal gases
Two laws formulated by James Prescott Joule: the electrical heating law (Q = I²Rt) and the thermodynamic result that an ideal gas's internal energy depends only on temperature; use
Kaon
Kaon (K meson): properties, types, and significance
Kelvin
Kelvin (unit of thermodynamic temperature)
Kennelly-Heaviside layer
Kennelly–Heaviside layer (E region of the ionosphere)
Kennelly–Heaviside layer
Kennelly–Heaviside layer (E region of the ionosphere)
Kilogram
Kilogram per cubic metre
Kilometres per hour
Kinematics
Kinematics: the geometry and description of motion
Kinematics studies how points, bodies and systems move, describing paths, velocity and acceleration without considering forces. It underpins robotics, biomechanics, engineering and
Kinetic energy
Kinetic energy (energy of motion)
Kinetic energy is the energy an object possesses due to motion. This article explains its classical formulas, forms, history, applications, and important distinctions including fra
Kinetic theory
Kinetics
Laminar flow
Large Hadron Collider
Large Hadron Collider (LHC)
The Large Hadron Collider is a 27 km circular particle accelerator at CERN beneath the Swiss–French border. It accelerates hadrons to near light speed to study fundamental particle
Laser
Laser: principles, types, history and applications
A laser is a device that produces intense, coherent, directional light by stimulated emission. This article explains how lasers work, common types, historical development, uses, an
Latent heat
Latent heat (energy involved in phase changes)
Laws of conservation
LC circuit
LC circuit: principles, behavior, and common applications
An LC circuit pairs an inductor (L) and a capacitor (C) to form a resonant electrical network used in tuning, filtering, and oscillators; ideal LC is lossless and exchanges energy
Length
Length (measurement and concepts)
Lens
Lens: optical elements, types, and applications
Lens (optics)
Lens (optics): overview, types, history and uses
Lenz's law
Lenz's Law: Electromagnetic induction and opposition to changing magnetic flux
Lepton
Leptons — elementary fermions not subject to the strong interaction
Leptons are spin-1/2 elementary particles of the Standard Model that do not feel the strong nuclear force. There are six flavors: three charged (electron, muon, tau) and three neut
Lever
Lever (simple machine): principles, types, uses, and history
Leyden jar
Lift (force)
Lift (force): Principles, mechanisms and applications
Light
Light: nature, spectrum, behavior, sources and uses
Overview of visible light as electromagnetic radiation: its dual nature, spectrum and colors, physical properties, common behaviors, principal sources like the Sun, and practical a
Light beam
Light clock
Light clock (special relativity thought experiment)
Light-second
Lightning
Lise Meitner
Lise Meitner: Pioneer of Nuclear Fission and 20th‑Century Physics
Locating (physics)
Longitudinal wave
Lorentz contraction
Lorentz contraction (length contraction)
Lorentz factor
Lorentz factor (γ) — the relativistic scaling of time, length and mass
The Lorentz factor γ = 1/√(1−(v/c)²) quantifies how time, distance and energy scale at speeds near light. It appears in Lorentz transformations, time dilation, length contraction a