Physics
Laws and principles filed under Nature & Cosmos / Physics.
Physics
Every guide includes meaning, mechanism, applications, limitations, related concepts, and traceable references.
Fundamental thermodynamic principle
Second Law of Thermodynamics
Entropy, irreversibility, heat-engine limits, statistical mechanics, open systems, information, and the arrow of time.
Foundational mechanics framework
Newton's Laws of Motion
Motion changes when forces act: inertia defines natural motion, net force determines acceleration, and interactions come in paired forces.
Linear constitutive relation for electrical conduction
Ohm's Law
Across an ohmic element at fixed physical conditions, voltage is proportional to current and resistance is the constant of proportionality.
Mechanical-energy relation along fluid flow
Bernoulli's Principle
Along a steady streamline in an ideal incompressible flow, pressure, kinetic energy, and gravitational potential energy trade while their sum remains constant.
Linear elastic constitutive relation
Hooke's Law
Within an elastic system's linear range, deformation is proportional to the load that produces it; remove the load and the system returns to its original configuration.
Electrostatic inverse-square relation
Coulomb's Law
The electrostatic force between two ideal point charges grows with the product of their charges and falls with the square of their separation.
Geometric-optics refraction relation
Snell's Law
When a ray crosses a uniform boundary between two optical media, its incident and refracted angles are linked by the media's refractive indices.
Electromagnetic induction law
Faraday's Law of Induction
A changing magnetic flux through a circuit produces an electromotive force around that circuit; its direction opposes the change that produced it.
Equation of state for an ideal gas
Ideal Gas Law
For a dilute equilibrium gas with negligible molecular volume and interactions, pressure, volume, amount, and absolute temperature are linked by one equation of state.
Thermal-radiation law
Stefan-Boltzmann Law
The total electromagnetic power emitted per unit area by an ideal blackbody rises with the fourth power of its absolute temperature.