physical quantity
quantitative characterization of an aspect of a physical entity, phenomenon, event, process, transformation, relation, system, or substance
loudness
subjective perception of sound pressure
heat transfer coefficient
measure of heat transfer on a surface
angular diameter
angular measurement describing how large a sphere or circle appears from a given point of view
angular resolution
ability of any image-forming device to distinguish small details of an object
sound particle displacement
instantaneous displacement of a particle from its equilibrium position in a medium as it transmits a sound wave
stimulus
in physiology, a detectable change in the internal or external surroundings
magnetic reluctance
in physics, the ratio of magnetomotive force to magnetic flux; the magnetic analogue of electrical resistance
linear stopping power
kinetic energy lost by charged particles traversing a given material per traversed distance
fracture toughness
stress intensity factor at which a crack's propagation increases drastically
reciprocal length
physical quantity
proper time
elapsed time between two events as measured by a clock that passes through both events
radius of curvature
radius of a circle which best approximates a curve in a given point
Curie constant
property that relates a material’s magnetic susceptibility to its temperature through Curie’s law
radiant flux
power carried by electromagnetic waves
electrotonic potential
passive spread of charge inside a neuron and between cardiac muscle cells or smooth muscle cells
azimuth angle
horizontal angle of a sphere
radiance
areal density of radiant intensity in a given direction
luminous efficacy of radiation
measure of how well a light source produces visible light
Holmberg radius
measure of the angular extent of a galaxy in the sky
Charge carrier density
charge carriers per volume; such as electrons, ions, "holes" or others
virtual water
hidden flow of water if food or other commodities are traded from one place to another; e.g. it takes 1340 m³ of water on average to produce 1000 kg of wheat
spectral flatness
measure used in digital signal processing to characterize an audio spectrum
stroke rate
measure for the number of cycles per time in rowing and canoeing
wave impedance
constant related to electromagnetic wave propagation in a medium
isothermal compressibility
negative relative change of volume per change of pressure at constant temperature
liquid water content
measure of the mass of the water in a cloud
period
smallest spatial or temporal interval after which a process repeats
intensive quantity
system's or substance's quantitative property that does not scale with the size or amount of the system or substance
reaction rate
for a reactant or product in a particular reaction is intuitively defined as how quickly or slowly a reaction takes place
Annual fuel utilization efficiency
measure of thermal efficiency
frequency drift
rate of change of the frequency
quantum correlation
expected change in physical characteristics as one quantum system passes through an interaction site
spectral flux density
quantity that describes the rate at which energy is transferred by electromagnetic radiation through a real or virtual surface, per unit surface area and per unit wavelength (or, equivalently, per unit frequency)
relative density
ratio of the density (mass per volume) of a substance to the density of a given reference material
potential gradient
local rate of change in potential with respect to displacement
stress tensor
tensor that describes the state of stress at a point inside a material
kinematic viscosity
characteristic of a fluid
intrinsic brightness
true brightness of an astronomical object, adjusting for distance and absorption of light
G-value
quantity in radiology
lower flammable limit
lower bound of the concentration range over which a flammable mixture of gas or vapour in air can be ignited at a given temperature and pressure
acceleration
follow by differentiation of velocity with respect to time in the context of special relativity
generalized velocity
time derivative of a generalized coordinate
relative permeability
ratio of permeability to the magnetic constant