QUDT VOCAB Quantity Kinds Release 2.1.14 The "Absolute Activity" is the exponential of the ratio of the chemical potential to $$RT$$ where $$R$$ is the gas constant and $$T$$ the thermodynamic temperature. http://goldbook.iupac.org/A00019.html http://www.iso.org/iso/catalogue_detail?csnumber=31894 $$\lambda_B = e^{\frac{\mu_B}{RT}}$$, where $$\mu_B$$ is the chemical potential of substance $$B$$, $$R$$ is the molar gas constant, and $$T$$ is thermodynamic temperature. $$\lambda_B$$ Absolute Activity "Absolute Humidity" is an amount of water vapor, usually discussed per unit volume. Absolute humidity in air ranges from zero to roughly 30 grams per cubic meter when the air is saturated at $$30 ^\circ C$$. The absolute humidity changes as air temperature or pressure changes. This is very inconvenient for chemical engineering calculations, e.g. for clothes dryers, where temperature can vary considerably. As a result, absolute humidity is generally defined in chemical engineering as mass of water vapor per unit mass of dry air, also known as the mass mixing ratio, which is much more rigorous for heat and mass balance calculations. Mass of water per unit volume as in the equation above would then be defined as volumetric humidity. Because of the potential confusion. http://en.wikipedia.org/wiki/Humidity http://en.wikipedia.org/wiki/Humidity#Absolute_humidity http://www.iso.org/iso/catalogue_detail?csnumber=31890 $$AH = \frac{\mathcal{M}_\omega}{\vee_{net}}$$, where $$\mathcal{M}_\omega$$ is the mass of water vapor per unit volume of total air and $$\vee_{net}$$ is water vapor mixture. AH Absolute Humidity "Absorbed Dose" (also known as Total Ionizing Dose, TID) is a measure of the energy deposited in a medium by ionizing radiation. It is equal to the energy deposited per unit mass of medium, and so has the unit $$J/kg$$, which is given the special name Gray ($$Gy$$). http://dbpedia.org/resource/Absorbed_dose http://en.wikipedia.org/wiki/Absorbed_dose http://www.iso.org/iso/catalogue_detail?csnumber=31895 $$D = \frac{d\bar{\varepsilon}}{dm}$$, where $$d\bar{\varepsilon}$$ is the mean energy imparted by ionizing radiation to an element of irradiated matter with the mass $$dm$$. D Note that the absorbed dose is not a good indicator of the likely biological effect. 1 Gy of alpha radiation would be much more biologically damaging than 1 Gy of photon radiation for example. Appropriate weighting factors can be applied reflecting the different relative biological effects to find the equivalent dose. The risk of stoctic effects due to radiation exposure can be quantified using the effective dose, which is a weighted average of the equivalent dose to each organ depending upon its radiosensitivity. When ionising radiation is used to treat cancer, the doctor will usually prescribe the radiotherapy treatment in Gy. When risk from ionising radiation is being discussed, a related unit, the Sievert is used. Absorbed Dose $$L^2/T^3$$ $$m^2/s^3$$ http://www.answers.com/topic/absorbed-dose-rate http://www.iso.org/iso/catalogue_detail?csnumber=31895 $$\dot{D} = \frac{dD}{dt}$$, where $$dD$$ is the increment of absorbed dose during time interval with duration $$dt$$. $$\dot{D}$$ "Absorbed Dose Rate" is the absorbed dose of ionizing radiation imparted at a given location per unit of time (second, minute, hour, or day). Absorbed Dose Rate https://en.wikipedia.org/wiki/Absorptance https://www.researchgate.net/post/Absorptance_or_absorbance $$\alpha = \frac{\Phi_a}{\Phi_m}$$, where $$\Phi_a$$ is the absorbed radiant flux or the absorbed luminous flux, and $$\Phi_m$$ is the radiant flux or luminous flux of the incident radiation. $$\alpha$$ Absorptance is the ratio of the radiation absorbed by a surface to that incident upon it. Also known as absorbance. belongs to SOQ-ISO Absorptance Acceleration is the (instantaneous) rate of change of velocity. Acceleration may be either linear acceleration, or angular acceleration. It is a vector quantity with dimension $$length/time^{2}$$ for linear acceleration, or in the case of angular acceleration, with dimension $$angle/time^{2}$$. In SI units, linear acceleration is measured in $$meters/second^{2}$$ ($$m \cdot s^{-2}$$) and angular acceleration is measured in $$radians/second^{2}$$. In physics, any increase or decrease in speed is referred to as acceleration and similarly, motion in a circle at constant speed is also an acceleration, since the direction component of the velocity is changing. http://dbpedia.org/resource/Acceleration http://en.wikipedia.org/wiki/Acceleration Acceleration The acceleration of freely falling bodies under the influence of terrestrial gravity, equal to approximately 9.81 meters (32 feet) per second per second. g Acceleration Of Gravity http://www.iso.org/iso/catalogue_detail?csnumber=31897 "Acceptor Density" is the number per volume of acceptor levels. n_a Acceptor Density "Acceptor Ionization Energy" is the ionization energy of an acceptor. http://en.wikipedia.org/wiki/Ionization_energy http://www.iso.org/iso/catalogue_detail?csnumber=31897 http://www.iso.org/iso/catalogue_detail?csnumber=31897 "Acceptor Ionization Energy" is the ionization energy of an acceptor. E_a Acceptor Ionization Energy http://en.wikipedia.org/wiki/Acoustic_impedance $$Z_a= \frac{p}{q} = \frac{p}{vS}$$, where $$p$$ is the sound pressure, $$q$$ is the sound volume velocity, $$v$$ is sound particle velocity, and $$S$$ is the surface area through which an acoustic wave of frequence $$f$$ propagates. Acoustic impedance at a surface is the complex quotient of the average sound pressure over that surface by the sound volume flow rate through that surface. Z Acoustic Impediance http://en.wikipedia.org/wiki/Action_(physics) http://www.iso.org/iso/catalogue_detail?csnumber=31889 $$S = \int Ldt$$, where $$L$$ is the Lagrange function and $$t$$ is time. An action is usually an integral over time. But for action pertaining to fields, it may be integrated over spatial variables as well. In some cases, the action is integrated along the path followed by the physical system. If the action is represented as an integral over time, taken a the path of the system between the initial time and the final time of the development of the system. The evolution of a physical system between two states is determined by requiring the action be minimized or, more generally, be stationary for small perturbations about the true evolution. This requirement leads to differential equations that describe the true evolution. Conversely, an action principle is a method for reformulating differential equations of motion for a physical system as an equivalent integral equation. Although several variants have been defined (see below), the most commonly used action principle is Hamilton's principle. S Action Action Time (sec) Action Time active-energy http://www.electropedia.org/iev/iev.nsf/display?openform&ievref=601-01-19 http://www.iso.org/iso/home/store/catalogue_tc/catalogue_detail.htm?csnumber=31891 $$W = \int_{t_1}^{t_2} p dt$$, where $$p$$ is instantaneous power and the integral interval is the time interval from $$t_1$$ to $$t_2$$. http://www.iso.org/iso/catalogue_detail?csnumber=43012 "Active Energy" is the electrical energy transformable into some other form of energy. W Active Energy $$Active Power$$ is, under periodic conditions, the mean value, taken over one period $$T$$, of the instantaneous power $$p$$. In complex notation, $$P = \mathbf{Re} \; \underline{S}$$, where $$\underline{S}$$ is $$\textit{complex power}$$". http://www.electropedia.org/iev/iev.nsf/display?openform&ievref=131-11-42 http://www.iso.org/iso/home/store/catalogue_tc/catalogue_detail.htm?csnumber=31891 $$P = \frac{1}{T}\int_{0}^{T} pdt$$, where $$T$$ is the period and $$p$$ is instantaneous power. P Active Power "Activity" is the number of decays per unit time of a radioactive sample, the term used to characterise the number of nuclei which disintegrate in a radioactive substance per unit time. Activity is usually measured in Becquerels ($$Bq$$), where 1 $$Bq$$ is 1 disintegration per second, in honor of the scientist Henri Becquerel. http://dbpedia.org/resource/Radioactive_decay http://en.wikipedia.org/wiki/Mass_number http://en.wikipedia.org/wiki/Radioactive_decay http://en.wikipedia.org/wiki/Radioactive_decay#Radioactive_decay_rates http://www.iso.org/iso/catalogue_detail?csnumber=31895 $$A = Z + N$$, where $$Z$$ is the atomic number and $$N$$ is the neutron number. Variation $$dN$$ of spontaneous number of nuclei $$N$$ in a particular energy state, in a sample of radionuclide, due to spontaneous nuclear transitions from this state during an infinitesimal time interval, divided by its duration $$dt$$, thus $$A = -\frac{dN}{dt}$$. A Activity http://en.wikipedia.org/wiki/Activity_coefficient http://www.iso.org/iso/catalogue_detail?csnumber=31894 $$f_B = \frac{\lambda_B}{(\lambda_B^*x_B)}$$, where $$\lambda_B$$ the absolute activity of substance $$B$$, $$\lambda_B^*$$ is the absolute activity of the pure substance $$B$$ at the same temperature and pressure, and $$x_B$$ is the amount-of-substance fraction of substance $$B$$. An "Activity Coefficient" is a factor used in thermodynamics to account for deviations from ideal behaviour in a mixture of chemical substances. In an ideal mixture, the interactions between each pair of chemical species are the same (or more formally, the enthalpy change of solution is zero) and, as a result, properties of the mixtures can be expressed directly in terms of simple concentrations or partial pressures of the substances present e.g. Raoult's law. Deviations from ideality are accommodated by modifying the concentration by an activity coefficient. f_B Activity Coefficient http://www.euronuclear.org/info/encyclopedia/activityconcentration.htm http://www.iso.org/iso/catalogue_detail?csnumber=31895 $$c_A = \frac{A}{V}$$, where $$A$$ is the activity of a sample and $$V$$ is its volume. The "Activity Concentration", also known as volume activity, and activity density, is . c_A Activity Concentration http://www.iso.org/iso/catalogue_detail?csnumber=43012 $$\overline{T_t}$$ "Activity Thresholds" are thresholds of sensitivity for radioactivity. Activity Thresholds http://www.iso.org/iso/catalogue_detail?csnumber=43012 "Adaptation" is the recovery of visual ability following exposure to light (dark adaptation). Adaptation "Admittance" is a measure of how easily a circuit or device will allow a current to flow. It is defined as the inverse of the impedance ($$Z$$). http://en.wikipedia.org/wiki/Admittance http://www.electropedia.org/iev/iev.nsf/display?openform&ievref=131-12-51 http://www.iso.org/iso/home/store/catalogue_tc/catalogue_detail.htm?csnumber=31891 $$Y = \frac{1}{Z}$$, where $$Z$$ is impedance. $$Y$$ Admittance The "Alpha Disintegration Energy" is the sum of the kinetic energy of the $$\alpha$$-particle produced in the disintegration process and the recoil energy of the product atom in the reference frame in which the emitting nucleus is at rest before its disintegration. $$Q_a$$ http://www.iso.org/iso/catalogue_detail?csnumber=31895 The "Alpha Disintegration Energy" is the sum of the kinetic energy of the alpha-particle produced in the disintegration process and the recoil energy of the product atom in the reference frame in which the emitting nucleus is at rest before its disintegration. Alpha Disintegration Energy http://dbpedia.org/resource/Altitude Altitude or height is defined based on the context in which it is used (aviation, geometry, geographical survey, sport, and more). As a general definition, altitude is a distance measurement, usually in the vertical or "up" direction, between a reference datum and a point or object. The reference datum also often varies according to the context. [Wikipedia] Altitude The ambient pressure on an object is the pressure of the surrounding medium, such as a gas or liquid, which comes into contact with the object. The SI unit of pressure is the pascal (Pa), which is a very small unit relative to atmospheric pressure on Earth, so kilopascals ($$kPa$$) are more commonly used in this context. p_a Ambient Pressure "Amount of Substance" is a standards-defined quantity that measures the size of an ensemble of elementary entities, such as atoms, molecules, electrons, and other particles. It is sometimes referred to as chemical amount. The International System of Units (SI) defines the amount of substance to be proportional to the number of elementary entities present. The SI unit for amount of substance is $$mole$$. It has the unit symbol $$mol$$. The mole is defined as the amount of substance that contains an equal number of elementary entities as there are atoms in 0.012kg of the isotope carbon-12. This number is called Avogadro's number and has the value $$6.02214179(30) \times 10^{23}$$. The only other unit of amount of substance in current use is the $$pound-mole$$ with the symbol $$lb-mol$$, which is sometimes used in chemical engineering in the United States. One $$pound-mole$$ is exactly $$453.59237 mol$$. $$M$$ $$mol$$ http://dbpedia.org/resource/Amount_of_substance http://en.wikipedia.org/wiki/Amount_of_substance http://www.iso.org/iso/catalogue_detail?csnumber=31894 n Amount of Substance http://en.wikipedia.org/wiki/Amount_of_substance_concentration http://www.iso.org/iso/catalogue_detail?csnumber=31894 $$C_B = \frac{n_B}{V}$$, where $$n_B$$ is the amount of substance $$B$$ and $$V$$ is the volume. "Amount of Substance of Concentration of B" is defined as the amount of a constituent divided by the volume of the mixture. C_B Amount of Substance of Concentration of B http://en.wikipedia.org/wiki/Amount_fraction http://www.iso.org/iso/catalogue_detail?csnumber=31894 $$x_B = \frac{n_B}{n}$$, where $$n_B$$ is the amount of substance $$B$$ and $$n$$ is the total amount of substance. "Amount of Substance of Fraction of B" is defined as tthe amount of a constituent divided by the total amount of all constituents in a mixture. X_B Amount of Substance of Fraction of B $$N/M$$ fix the numerator and denominator dimensions Amount of Substance per Unit Mass The "Variation of Molar Mass" of a gas as a function of pressure. Molar Mass variation due to Pressure $$M/L^3$$ $$mol/m^3$$ http://www.ask.com/answers/72367781/what-is-defined-as-the-amount-of-substance-per-unit-of-volume https://en.wikipedia.org/wiki/Molar_concentration The amount of substance per unit volume is called the molar density. Molar density is an intensive property of a substance and depends on the temperature and pressure. Amount of Substance per Unit Volume The abstract notion of angle. Narrow concepts include plane angle and solid angle. While both plane angle and solid angle are dimensionless, they are actually length/length and area/area respectively. http://dbpedia.org/resource/Angle Angle $$\alpha$$ Angle of attack is the angle between the oncoming air or relative wind and a reference line on the airplane or wing. Angle Of Attack http://en.wikipedia.org/wiki/Optical_rotation http://www.iso.org/iso/catalogue_detail?csnumber=31894 $$\alpha$$ The "Angle of Optical Rotation" is the angle through which plane-polarized light is rotated clockwise, as seen when facing the light source, in passing through an optically active medium. Angle of Optical Rotation Angular acceleration is the rate of change of angular velocity over time. Measurement of the change made in the rate of change of an angle that a spinning object undergoes per unit time. It is a vector quantity. Also called Rotational acceleration. In SI units, it is measured in radians per second squared ($$rad/s^2$$), and is usually denoted by the Greek letter alpha. U/T^2 $$/s^2$$ $$U/T^2$$ http://dbpedia.org/resource/Angular_acceleration Angular Acceleration "Angular Cross-section" is the cross-section for ejecting or scattering a particle into an elementary cone, divided by the solid angle $$d\Omega$$ of that cone. http://en.wikipedia.org/wiki/Cross_section_(physics) http://www.iso.org/iso/catalogue_detail?csnumber=31895 $$\sigma = \int \sigma_\Omega d\Omega$$ $$\sigma_\Omega$$ Angular Cross-section $$\theta$$ Angular distance travelled by orbiting vehicle measured from the azimuth of closest approach. Angular Distance "Angular frequency", symbol $$\omega$$ (also referred to by the terms angular speed, radial frequency, circular frequency, orbital frequency, radian frequency, and pulsatance) is a scalar measure of rotation rate. Angular frequency (or angular speed) is the magnitude of the vector quantity angular velocity. http://dbpedia.org/resource/Angular_frequency http://en.wikipedia.org/wiki/Angular_frequency http://www.iso.org/iso/catalogue_detail?csnumber=43012 $$\omega = 2\pi f$$, where $$f$$ is frequency. $$\omega$$ belongs to SOQ-ISO Angular Frequency The Angular Impulse, also known as angular momentum, is the moment of linear momentum around a point. It is defined as$$H = \int Mdt$$, where $$M$$ is the moment of force and $$t$$ is time. http://dbpedia.org/resource/AngularMomentum http://emweb.unl.edu/NEGAHBAN/EM373/note13/note.htm http://www.iso.org/iso/catalogue_detail?csnumber=31889 H Angular Impulse $$L^2 \cdot M/T$$ $$kg \cdot m^2/s$$ http://dbpedia.org/resource/Angular_momentum http://en.wikipedia.org/wiki/Angular_momentum http://www.iso.org/iso/catalogue_detail?csnumber=31889 $$L = I\omega$$, where $$I$$ is the moment of inertia, and $$\omega$$ is the angular velocity. Angular Momentum of an object rotating about some reference point is the measure of the extent to which the object will continue to rotate about that point unless acted upon by an external torque. In particular, if a point mass rotates about an axis, then the angular momentum with respect to a point on the axis is related to the mass of the object, the velocity and the distance of the mass to the axis. While the motion associated with linear momentum has no absolute frame of reference, the rotation associated with angular momentum is sometimes spoken of as being measured relative to the fixed stars. \textit{Angular Momentum}, \textit{Moment of Momentum}, or \textit{Rotational Momentum", is a vector quantity that represents the product of a body's rotational inertia and rotational velocity about a particular axis. L Angular Momentum "Angular Reciprocal Lattice Vector" is a vector whose scalar products with all fundamental lattice vectors are integral multiples of $$2\pi$$. http://www.matter.org.uk/diffraction/geometry/lattice_vectors.htm http://www.iso.org/iso/catalogue_detail?csnumber=31897 G Angular Reciprocal Lattice Vector Angular Velocity refers to how fast an object rotates or revolves relative to another point. $$/s$$ $$U/T$$ http://dbpedia.org/resource/Angular_velocity https://en.wikipedia.org/wiki/Angular_velocity The change of angle per unit time; specifically, in celestial mechanics, the change in angle of the radius vector per unit time. Angular Velocity http://en.wikipedia.org/wiki/Wavenumber http://www.iso.org/iso/catalogue_detail?csnumber=31897 $$k = \frac{2\pi}{\lambda}= \frac{2\pi\upsilon}{\upsilon_p}=\frac{\omega}{\upsilon_p}$$, where $$\upsilon$$ is the frequency of the wave, $$\lambda$$ is the wavelength, $$\omega = 2\pi \upsilon$$ is the angular frequency of the wave, and $$\upsilon_p$$ is the phase velocity of the wave. Alternatively: $$k = \frac{p}{\hbar}$$, where $$p$$ is the linear momentum of quasi free electrons in an electron gas and $$\hbar$$ is the reduced Planck constant ($$h$$ divided by $$2\pi$$); for phonons, its magnitude is $$k = \frac{2\pi}{\lambda}$$, where $$\lambda$$ is the wavelength of the lattice vibrations. "wavenumber" is the spatial frequency of a wave - the number of waves that exist over a specified distance. More formally, it is the reciprocal of the wavelength. It is also the magnitude of the wave vector. k belongs to SOQ-ISO Angular Wavenumber Apogee radius of an elliptical orbit r_2 Apogee Radius "Apparent Power" is the product of the rms voltage $$U$$ between the terminals of a two-terminal element or two-terminal circuit and the rms electric current I in the element or circuit. Under sinusoidal conditions, the apparent power is the modulus of the complex power. http://www.electropedia.org/iev/iev.nsf/display?openform&ievref=131-11-41 http://www.iso.org/iso/home/store/catalogue_tc/catalogue_detail.htm?csnumber=31891 $$\left | \underline{S} \right | = UI$$, where $$U$$ is rms value of voltage and $$I$$ is rms value of electric current. $$\left | \underline{S} \right |$$ Apparent Power cm^2 $$m^2$$ $$L^2$$ http://dbpedia.org/resource/Area Area is a quantity expressing the two-dimensional size of a defined part of a surface, typically a region bounded by a closed curve. Area $$L^2 \cdot U$$ $$m^2$$ Area Angle $$ft^2/s$$ $$m^2/s$$ $$L^2/T$$ Area per Time Area Ratio $$K \cdot m^2$$ $$\Theta \cdot L^2$$ Area Temperature $$L^2/\Theta$$ $$m^2/K$$ http://en.wikipedia.org/area_thermal_expansion When the temperature of a substance changes, the energy that is stored in the intermolecular bonds between atoms changes. When the stored energy increases, so does the length of the molecular bonds. As a result, solids typically expand in response to heating and contract on cooling; this dimensional response to temperature change is expressed by its coefficient of thermal expansion. Area Thermal Expansion $$L^2 \cdot T$$ $$m^2 \cdot s$$ Area Time Area Time Temperature heat-flow-rate http://en.wikipedia.org/wiki/Rate_of_heat_flow $$\varphi = \frac{\Phi}{A}$$, where $$\Phi$$ is heat flow rate and $$A$$ is area. http://www.iso.org/iso/catalogue_detail?csnumber=31890 Density of heat flow rate. φ Aeric Heat Flow Rate An Asset is an economic resource owned by a business or company. Simply stated, assets are things of value that can be readily converted into cash (although cash itself is also considered an asset). Asset The pressure exerted by the weight of the air above it at any point on the earth's surface. At sea level the atmosphere will support a column of mercury about $$760 mm$$ high. This decreases with increasing altitude. The standard value for the atmospheric pressure at sea level in SI units is $$101,325 pascals$$. http://dbpedia.org/resource/Atmospheric_pressure http://www.oxfordreference.com/views/ENTRY.html?subview=Main&entry=t83.e178 Atmospheric Pressure http://reference.iucr.org/dictionary/Atomic_scattering_factor http://www.iso.org/iso/catalogue_detail?csnumber=31897 $$f = \frac{E_a}{E_e}$$, where $$E_a$$ is the radiation amplitude scattered by the atom and $$E_e$$ is the radiation ampliture scattered by a single electron. "Atom Scattering Factor" is measure of the scattering power of an isolated atom. f Atom Scattering Factor http://en.wikipedia.org/wiki/Attenuation_coefficient $$\mu_a = -\frac{\mu}{n}$$, where $$\mu$$ is the linear attenuation coefficient and $$n$$ is the number density of the atoms in the substance. http://www.iso.org/iso/catalogue_detail?csnumber=31895 "Atomic Attenuation Coefficient" is a measurement of how strongly a chemical species or substance absorbs or scatters light at a given wavelength, per the number of atoms in the substance. μₐ Atomic Attenuation Coefficient http://www.answers.com/topic/atomic-charge The electric charge of an ion, equal to the number of electrons the atom has gained or lost in its ionization multiplied by the charge on one electron. Atomic Charge http://en.wikipedia.org/wiki/Atomic_mass http://www.iso.org/iso/catalogue_detail?csnumber=31895 The "Atomic Mass" is the mass of a specific isotope, most often expressed in unified atomic mass units. m_a Atomic Mass http://en.wikipedia.org/wiki/Atomic_number http://www.iso.org/iso/home/store/catalogue_tc/catalogue_detail.htm?csnumber=31895 http://www.iso.org/iso/catalogue_detail?csnumber=31894 The "Atomic Number", also known as the proton number, is the number of protons found in the nucleus of an atom and therefore identical to the charge number of the nucleus. A nuclide is a species of atom with specified numbers of protons and neutrons. Nuclides with the same value of Z but different values of N are called isotopes of an element. The ordinal number of an element in the periodic table is equal to the atomic number. The atomic number equals the charge of the nucleus in units of the elementary charge. Z Atomic Number http://en.wikipedia.org/wiki/Attenuation_coefficient $$F(x) = Ae^{-\alpha x} \cos{[\beta (x - x_0)]}$$, then $$\alpha$$ is the attenuation coefficient and $$\beta$$ is the phase coefficient. $$\alpha$$ The attenuation coefficient is a quantity that characterizes how easily a material or medium can be penetrated by a beam of light, sound, particles, or other energy or matter. A large attenuation coefficient means that the beam is quickly "attenuated" (weakened) as it passes through the medium, and a small attenuation coefficient means that the medium is relatively transparent to the beam. The Attenuation Coefficient is also called linear attenuation coefficient, narrow beam attenuation coefficient, or absorption coefficient. belongs to SOQ-ISO Attenuation Coefficient http://www.iso.org/iso/catalogue_detail?csnumber=43012 $$\overline{T_a}$$ "Auditory Thresholds" is the thresholds of sensitivity to auditory signals and other input to the ear or the sense of hearing. Auditory Thresholds H Magnetic Fields surround magnetic materials and electric currents and are detected by the force they exert on other magnetic materials and moving electric charges. The electric and magnetic fields are two interrelated aspects of a single object, called the electromagnetic field. A pure electric field in one reference frame is observed as a combination of both an electric field and a magnetic field in a moving reference frame. The Auxillary Magnetic Field, H characterizes how the true Magnetic Field B influences the organization of magnetic dipoles in a given medium. Auxillary Magnetic Field $$W_i = \frac{E_k}{N_i}$$, where $$E_k$$ is the initial kinetic energy of an ionizing charged particle and $$N_i$$ is the total ionization produced by that particle. http://www.iso.org/iso/catalogue_detail?csnumber=31895 "Average Energy Loss per Elementary Charge Produced" is also referred to as average energy loss per ion pair formed. W_i Average Energy Loss per Elementary Charge Produced AHEP Average Head End Pressure http://everything2.com/title/Average+logarithmic+energy+decrement+per+collision http://www.iso.org/iso/catalogue_detail?csnumber=31895 $$\xi$$ "Average Logarithmic Energy Decrement" is a measure of the amount of energy a neutron loses upon colliding with various nuclei. It is the average value of the increase in lethargy in elastic collisions between neutrons and nuclei whose kinetic energy is negligible compared with that of the neutrons. Average Logarithmic Energy Decrement Avg Specific Impulse (lbf-sec/lbm) Average Specific Impulse Average Vacuum Thrust AVT http://dbpedia.org/resource/Torque http://en.wikipedia.org/wiki/Bending_moment http://www.iso.org/iso/catalogue_detail?csnumber=31889 $$M_b = M \cdot e_Q$$, where $$M$$ is the momentof force and $$e_Q$$ is a unit vector directed along a $$Q-axis$$ with respect to which the torque is considered. A bending moment exists in a structural element when a moment is applied to the element so that the element bends. It is the component of moment of force perpendicular to the longitudinal axis of a beam or a shaft. M_b Bending Moment of Force http://en.wikipedia.org/wiki/Decay_energy http://www.iso.org/iso/catalogue_detail?csnumber=31895 "Beta Disintegration Energy" is the energy released by a beta particle radioactive decay. It is the sum of the maximum beta-particle kinetic energy and the recoil energy of the atom produced in the reference frame in which the emitting nucleus is at rest before its disintegration. Qᵦ Beta Disintegration Energy $$\theta$$ Pitch angle in bevel gears is the angle between an element of a pitch cone and its axis. In external and internal bevel gears, the pitch angles are respectively less than and greater than 90 degrees. Bevel Gear Pitch Angle http://encyclopedia2.thefreedictionary.com/binding+fraction http://www.iso.org/iso/catalogue_detail?csnumber=31895 $$b = \frac{B_r}{A}$$, where $$B_r$$ is the relative mass defect and $$A$$ is the nucleon number. The "Binding Fraction" is the ratio of the binding energy of a nucleus to the atomic mass number. b Binding Fraction The blood sugar level, blood sugar concentration, or blood glucose level is the amount of glucose present in the blood of humans and other animals. Glucose is a simple sugar and approximately 4 grams of glucose are present in the blood of humans at all times. The body tightly regulates blood glucose levels as a part of metabolic homeostasis. Glucose is stored in skeletal muscle and liver cells in the form of glycogen; in fasted individuals, blood glucose is maintained at a constant level at the expense of glycogen stores in the liver and skeletal muscle. [Wikipedia] $$\\$$ There are two main methods of describing concentrations: by weight, and by molecular count. Weights are in grams, molecular counts in moles. A mole is $$6.022\times 10^{23}$$ molecules.) In both cases, the unit is usually modified by $$milli-$$ or $$micro-$$ or other prefix, and is always $$per$$ some volume, often a liter. Conversion factors depend on the molecular weight of the substance in question. $$\\$$ $$mmol/L$$ is millimoles/liter, and is the world standard unit for measuring glucose in blood. Specifically, it is the designated SI (Systeme International) unit. 'World standard' is not universal; not only the US but a number of other countries use mg/dl. A mole is about $$6\times 10^{23}$$ molecules. $$\\$$ $$mg/dL$$ (milligrams/deciliter) is the traditional unit for measuring bG (blood glucose). There is a trend toward using $$mmol/L$$ however mg/dL is much in practice. Some use is made of $$mmol/L$$ as the primary unit with $$mg/dL$$ quoted in parentheses. This acknowledges the large base of health care providers, researchers and patients who are already familiar with $$mg/dL|). http://www.faqs.org/faqs/diabetes/faq/part1/section-9.html citation: https://en.wikipedia.org/wiki/Blood_sugar_level Blood Glucose Level The blood sugar level, blood sugar concentration, or blood glucose level is the amount of glucose present in the blood of humans and other animals. Glucose is a simple sugar and approximately 4 grams of glucose are present in the blood of humans at all times. The body tightly regulates blood glucose levels as a part of metabolic homeostasis. Glucose is stored in skeletal muscle and liver cells in the form of glycogen; in fasted individuals, blood glucose is maintained at a constant level at the expense of glycogen stores in the liver and skeletal muscle. [Wikipedia] \(\\$$ There are two main methods of describing concentrations: by weight, and by molecular count. Weights are in grams, molecular counts in moles. A mole is $$6.022\times 10^{23}$$ molecules.) In both cases, the unit is usually modified by $$milli-$$ or $$micro-$$ or other prefix, and is always $$per$$ some volume, often a liter. Conversion factors depend on the molecular weight of the substance in question. $$\\$$ $$mmol/L$$ is millimoles/liter, and is the world standard unit for measuring glucose in blood. Specifically, it is the designated SI (Systeme International) unit. 'World standard' is not universal; not only the US but a number of other countries use mg/dl. A mole is about $$6\times 10^{23}$$ molecules. $$\\$$ $$mg/dL$$ (milligrams/deciliter) is the traditional unit for measuring bG (blood glucose). There is a trend toward using $$mmol/L$$ however mg/dL is much in practice. Some use is made of $$mmol/L$$ as the primary unit with $$mg/dL$$ quoted in parentheses. This acknowledges the large base of health care providers, researchers and patients who are already familiar with $$mg/dL|). http://www.faqs.org/faqs/diabetes/faq/part1/section-9.html citation: https://en.wikipedia.org/wiki/Blood_sugar_level Blood Glucose Level by Mass \(\textit{Body Mass Index}$$, BMI, is an index of weight for height, calculated as: $$BMI = \frac{M_{body}}{H}$$, where $$M_{body}$$ is body mass in kg, and $$H$$ is height in metre. The BMI has been used as a guideline for defining whether a person is overweight because it minimizes the effect of height, but it does not take into consideration other important factors, such as age and body build. The BMI has also been used as an indicator of obesity on the assumption that the higher the index, the greater the level of body fat. http://www.oxfordreference.com/view/10.1093/acref/9780198631477.001.0001/acref-9780198631477-e-254 BMI Body Mass Index BMI http://reference.iucr.org/dictionary/Bragg_angle http://www.iso.org/iso/catalogue_detail?csnumber=31897 $$2d\sin{\vartheta} = n\lambda$$ $$\vartheta$$ "Bragg Angle" describes the condition for a plane wave to be diffracted from a family of lattice planes, the angle between the wavevector of the incident plane wave, and the lattice planes. Bragg Angle http://dbpedia.org/resource/Length http://en.wiktionary.org/wiki/breadth http://www.iso.org/iso/catalogue_detail?csnumber=43012 "Breadth" is the extent or measure of how broad or wide something is. b Breadth B Buckling Factor http://en.wikipedia.org/wiki/Bulk_modulus http://www.iso.org/iso/catalogue_detail?csnumber=31889 $$K = \frac{p}{\vartheta}$$, where $$p$$ is pressure and $$\vartheta$$ is volume strain. The bulk modulus of a substance measures the substance's resistance to uniform compression. It is defined as the ratio of the infinitesimal pressure increase to the resulting relative decrease of the volume. K Bulk Modulus http://en.wikipedia.org/wiki/Burgers_vector http://www.iso.org/iso/catalogue_detail?csnumber=31897 "Burgers Vector" is the vector characterizing a dislocation, i.e. the closing vector in a Burgers circuit encircling a dislocation line. b Burgers Vector Burn Rate t Burn Time cg http://www.grc.nasa.gov/WWW/k-12/airplane/cg.html Center of Gravity in the X axis cg http://www.grc.nasa.gov/WWW/k-12/airplane/cg.html Center of Gravity in the Y axis cg http://www.grc.nasa.gov/WWW/k-12/airplane/cg.html Center of Gravity in the X axis The point at which the distributed mass of a composite body can be acted upon by a force without inducing any rotation of the composite body. R http://en.wikipedia.org/wiki/Center_of_mass Center of Mass (CoM) COM Contractual mass requirement of a delivered item. Note that The term 'control mass' is sometimes utilized as a limit in lieu of CEI mass when a CEI mass does not exist. The term 'Interface Control Document Mass' is another alternative for specifying a contractual mass requirement. Contract End Item (CEI) Specification Mass. CEI The upper design gross mass limit of a system at a specified mission event against which margins are calculated after accounting for basic masses of flight hardware, MGA, and uncertainties. It may include propellants, crew, and cargo. Control Mass. http://en.wikipedia.org/wiki/Partition_function_(statistical_mechanics) http://www.iso.org/iso/catalogue_detail?csnumber=31894 $$Z = \sum_r e^{-\frac{E_r}{kT}}$$, where the sum is over all quantum states consistent with given energy, volume, external fields, and content, $$E_r$$ is the energy in the $$rth$$ quantum state, $$k$$ is the Boltzmann constant, and $$T$$ is thermodynamic temperature. A "Canonical Partition Function" applies to a canonical ensemble, in which the system is allowed to exchange heat with the environment at fixed temperature, volume, and number of particles. Z Canonical Partition Function $$A^2 \cdot s^4/kg \cdot m^2$$ $$I^2 \cdot T^4/L^2 \cdot M$$ http://dbpedia.org/resource/Capacitance http://www.iso.org/iso/home/store/catalogue_tc/catalogue_detail.htm?csnumber=31891 http://www.iso.org/iso/catalogue_detail?csnumber=43012 $$C = Q/U$$, where $$Q$$ is electric charge and $$V$$ is voltage. "Capacitance" is the ability of a body to hold an electrical charge; it is quantified as the amount of electric charge stored for a given electric potential. Capacitance is a scalar-valued quantity. C Capacitance http://dbpedia.org/resource/Capacity In computer operations, (a) the largest quantity which can be stored, processed, or transferred; (b) the largest number of digits or characters which may regularly be processed; (c) the upper and lower limits of the quantities which may be processed. In other contexts, the amount of material that can be stored, such as fuel or food. TBD Capacity http://en.wikipedia.org/wiki/Carrier_lifetime http://www.iso.org/iso/catalogue_detail?csnumber=31897 $$\tau, \tau_n, \tau_p$$ "Carrier LifetIme" is a time constant for recombination or trapping of minority charge carriers in semiconductors. Carrier LifetIme area http://en.wikipedia.org/wiki/Area $$A = \int\int dxdy$$, where $$x$$ and $$y$$ are cartesian coordinates. http://www.iso.org/iso/catalogue_detail?csnumber=43012 "Area" is a quantity that expresses the extent of a two-dimensional surface or shape, or planar lamina, in the plane. A Cartesian Area http://en.wikipedia.org/wiki/Cartesian_coordinate_system http://www.iso.org/iso/catalogue_detail?csnumber=43012 "Cartesian Coordinates" specify each point uniquely in a plane by a pair of numerical coordinates, which are the signed distances from the point to two fixed perpendicular directed lines, measured in the same unit of length. x, y, z Cartesian Coordinates http://en.wikipedia.org/wiki/Volume http://www.iso.org/iso/catalogue_detail?csnumber=43012 $$V = \int\int\int dxdydz$$, where $$x$$, $$y$$, and $$z$$ are cartesian coordinates. "Volume" is the quantity of three-dimensional space enclosed by some closed boundary, for example, the space that a substance (solid, liquid, gas, or plasma) or shape occupies or contains. V Volume An index of the actual or potential activity of a catalyst. The catalytic activity of an enzyme or an enzyme-containing preparation is defined as the property measured by the increase in the rate of conversion of a specified chemical reaction that the enzyme produces in a specified assay system. Catalytic activity is an extensive quantity and is a property of the enzyme, not of the reaction mixture; it is thus conceptually different from rate of conversion although measured by and equidimensional with it. The unit for catalytic activity is the $$katal$$; it may also be expressed in mol $$s^{-1}$$. Dimensions: $$N T^{-1}$$. Former terms such as catalytic ability, catalytic amount, and enzymic activity are no er recommended. Derived quantities are molar catalytic activity, specific catalytic activity, and catalytic activity concentration. Source(s): <a href="http://www.answers.com/topic/catalytic-activity-biochemistry">www.answers.com</a> $$M/T$$ $$mol/s$$ http://dbpedia.org/resource/Catalysis Catalytic Activity http://www.iso.org/iso/catalogue_detail?csnumber=31890 "Celsius Temperature", the thermodynamic temperature $$T_0$$, is exactly $$0.01$$kelvin below the thermodynamic temperature of the triple point of water. $$t = T - T_0$$, where $$T$$ is Thermodynamic Temperature and $$T_0 = 273.15 K$$. "Celsius Temperature", the thermodynamic temperature T_0, is exactly 0.01 kelvin below the thermodynamic temperature of the triple point of water. Celsius temperature Characteristic impedance at a point in a non-dissipative medium and for a plane progressive wave, the quotient of the sound pressure $$p$$ by the component of the sound particle velocity $$v$$ in the direction of the wave propagation. http://en.wikipedia.org/wiki/Acoustic_impedance#Characteristic_acoustic_impedance $$Z_c = pc$$, where $$p$$ is the sound pressure and $$c$$ is the phase speed of sound. Z belongs to SOQ-ISO Characteristic Acoustic Impedance Characteristic velocity or $$c^{*}$$ is a measure of the combustion performance of a rocket engine independent of nozzle performance, and is used to compare different propellants and propulsion systems. $$c^{*}$$ Characteristic Velocity http://en.wikipedia.org/wiki/Charge_number http://www.iso.org/iso/catalogue_detail?csnumber=31894 The "Charge Number", or just valance of an ion is the coefficient that, when multiplied by the elementary charge, gives the ion's charge. z Charge Number http://en.wikipedia.org/wiki/Chemical_affinity http://www.iso.org/iso/catalogue_detail?csnumber=31894 $$A = -\sum \nu_b\mu_B$$, where $$\nu_b$$ is the stoichiometric number of substance $$B$$ and $$\mu_B$$ is the chemical potential of substance $$B$$. In chemical physics and physical chemistry, "Chemical Affinity" is the electronic property by which dissimilar chemical species are capable of forming chemical compounds. Chemical affinity can also refer to the tendency of an atom or compound to combine by chemical reaction with atoms or compounds of unlike composition. A Chemical Affinity http://en.wikipedia.org/wiki/Chemical_potential http://www.iso.org/iso/catalogue_detail?csnumber=31894 $$\mu_B = (\frac{\partial G}{\partial n_B})_{T,p,n_i}$$, where $$G$$ is Gibbs energy, and $$n_B$$ is the amount of substance $$B$$. $$\mu_B$$ "Chemical Potential", also known as partial molar free energy, is a form of potential energy that can be absorbed or released during a chemical reaction. Chemical Potential http://dbpedia.org/resource/Circulation_%28fluid_dynamics%29 $$\Gamma$$ In fluid dynamics, circulation is the line integral around a closed curve of the fluid velocity. It has dimensions of length squared over time. Circulation r_o Closest Approach Radius $$M/\Theta \cdot T^3$$ $$kg/K \cdot s^3$$ $$heat-xfer-coeff$$ http://en.wikipedia.org/wiki/Heat_transfer_coefficient "Coefficient of Heat Transfer", in thermodynamics and in mechanical and chemical engineering, is used in calculating the heat transfer, typically by convection or phase transition between a fluid and a solid. The heat transfer coefficient is the proportionality coefficient between the heat flux, that is heat flow per unit area, $$q/A$$, and the thermodynamic driving force for the flow of heat (that is, the temperature difference, $$\bigtriangleup T$$). Areic heat flow rate divided by thermodynamic temperature difference. In building technology, the $$\textit{Coefficient of Heat Transfer}$$, is often called $$\textit{thermal transmittance}$$, with the symbol $$U$$. $$\textit{Coefficient of Heat Transfer}$$, has SI units in watts per squared meter kelvin: $$W/(m^2 \cdot K)$$ . $$K = \frac{\varphi}{T}$$, where $$\varphi$$ is areic heat flow rate and $$T$$ is thermodynamic temperature difference. $$\kappa$$ "Coefficient of Heat Transfer", in thermodynamics and in mechanical and chemical engineering, is used in calculating the heat transfer, typically by convection or phase transition between a fluid and a solid. The heat transfer coefficient is the proportionality coefficient between the heat flux, that is heat flow per unit area, q/A, and the thermodynamic driving force for the flow of heat (that is, the temperature difference, (Delta T). Areic heat flow rate divided by thermodynamic temperature difference. In building technology, the "Coefficient of Heat Transfer", is often called "thermal transmittance}" with the symbol "U". It has SI units in watts per squared meter kelvin. Coefficient of heat transfer $$\textit{Coercivity}$$, also referred to as $$\textit{Coercive Field Strength}$$, is the magnetic field strength to be applied to bring the magnetic flux density in a substance from its remaining magnetic flux density to zero. This is defined as the coercive field strength in a substance when either the magnetic flux density or the magnetic polarization and magnetization is brought from its value at magnetic saturation to zero by monotonic reduction of the applied magnetic field strength. The quantity which is brought to zero should be stated, and the appropriate symbol used: $$H_{cB}$$, $$H_{cJ}$$ or $$H_{cM}$$ for the coercivity relating to the magnetic flux density, the magnetic polarization or the magnetization respectively, where $$H_{cJ} = H_{cM}$$. http://www.electropedia.org/iev/iev.nsf/display?openform&ievref=121-12-69 http://www.iso.org/iso/home/store/catalogue_tc/catalogue_detail.htm?csnumber=31891 H_{c,B} Coercivity http://en.wikipedia.org/wiki/Coherence_length http://www.iso.org/iso/catalogue_detail?csnumber=31897 "Coherence Length" characterizes the distance in a superconductor over which the effect of a perturbation is appreciable. ξ Coherence Length http://www.iso.org/iso/catalogue_detail?csnumber=43012 $$\overline{T_c}$$ "Cold Receptor Threshold" is the threshold of cold-sensitive free nerve-ending. Cold Receptor Threshold http://www.iso.org/iso/catalogue_detail?csnumber=43012 $$h = h_r + h_c + h_k$$, where $$h_r$$ is the linear radiative heat transfer coefficient, $$h_c$$ is the convective heat transfer coefficient, and $$h_k$$ is the conductive heat transfer coefficient. "Combined Non Evaporative Heat Transfer Coefficient" is the h Combined Non Evaporative Heat Transfer Coefficient T_c Combustion Chamber Temperature "Complex Power", under sinusoidal conditions, is the product of the phasor $$U$$ representing the voltage between the terminals of a linear two-terminal element or two-terminal circuit and the complex conjugate of the phasor $$I$$ representing the electric current in the element or circuit. $$complex-power$$ http://www.electropedia.org/iev/iev.nsf/display?openform&ievref=131-11-39 http://www.iso.org/iso/home/store/catalogue_tc/catalogue_detail.htm?csnumber=31891 $$\underline{S} = \underline{U}\underline{I^*}$$, where $$\underline{U}$$ is voltage phasor and $$\underline{I^*}$$ is the complex conjugate of the current phasor. $$\underline{S}$$ Complex Power http://en.wikipedia.org/wiki/Compressibility http://www.iso.org/iso/catalogue_detail?csnumber=31889 $$\chi = -(\frac{1}{V})\frac{dV}{d\rho}$$, where $$V$$ is volume and $$p$$ is pressure. $$\chi$$ Compressibility is a measure of the relative volume change of a fluid or solid as a response to a pressure (or mean stress) change. Compressibility The compressibility factor ($$Z$$) is a useful thermodynamic property for modifying the ideal gas law to account for the real gas behaviour. The closer a gas is to a phase change, the larger the deviations from ideal behavior. It is simply defined as the ratio of the molar volume of a gas to the molar volume of an ideal gas at the same temperature and pressure. Values for compressibility are calculated using equations of state (EOS), such as the virial equation and van der Waals equation. The compressibility factor for specific gases can be obtained, with out calculation, from compressibility charts. These charts are created by plotting Z as a function of pressure at constant temperature. http://www.iso.org/iso/catalogue_detail?csnumber=31890 Z Compressibility Factor http://dbpedia.org/resource/Concentration http://en.wikipedia.org/wiki/Concentration In chemistry, concentration is defined as the abundance of a constituent divided by the total volume of a mixture. Furthermore, in chemistry, four types of mathematical description can be distinguished: mass concentration, molar concentration, number concentration, and volume concentration. The term concentration can be applied to any kind of chemical mixture, but most frequently it refers to solutes in solutions. Concentration $$\textit{Conductance}$$, for a resistive two-terminal element or two-terminal circuit with terminals A and B, quotient of the electric current i in the element or circuit by the voltage $$u_{AB}$$ between the terminals: $$G = \frac{1}{R}$$, where the electric current is taken as positive if its direction is from A to B and negative in the opposite case. The conductance of an element or circuit is the inverse of its resistance. http://www.electropedia.org/iev/iev.nsf/display?openform&ievref=131-12-06 http://www.iso.org/iso/home/store/catalogue_tc/catalogue_detail.htm?csnumber=31891 $$G = Re\underline{Y}$$, where $$\underline{Y}$$ is admittance. Alternatively: $$G = \frac{1}{R}$$, where $$R$$ is resistance. G Conductance http://www.iso.org/iso/catalogue_detail?csnumber=43012 "Conduction Speed" is the speed of impulses in nerve fibers. c Conduction Speed http://www.iso.org/iso/catalogue_detail?csnumber=43012 $$\Phi_k$$ "Conductive Heat Transfer Rate" is proportional to temperature gradient and area of contact. Conductive Heat Transfer Rate http://www.electropedia.org/iev/iev.nsf/display?openform&ievref=121-12-03 http://www.iso.org/iso/home/store/catalogue_tc/catalogue_detail.htm?csnumber=31891 $$\mathbf{J} = \sigma \mathbf{E}$$, where $$\mathbf{J}$$ is electric current density, and $$\mathbf{E}$$ is electric field strength. $$\gamma$$ $$\sigma$$ "Conductivity" is a scalar or tensor quantity the product of which by the electric field strength in a medium is equal to the electric current density. For an isotropic medium the conductivity is a scalar quantity; for an anisotropic medium it is a tensor quantity. Conductivity http://www.iso.org/iso/catalogue_detail?csnumber=43012 $$\Phi_c$$ "Convective Heat Transfer" is convective heat transfer coefficient multiplied by temperature difference and exchange area. Convective Heat Transfer http://www.electropedia.org/iev/iev.nsf/display?openform&ievref=161-03-18 http://www.iso.org/iso/home/store/catalogue_tc/catalogue_detail.htm?csnumber=31891 For inductive coupling between two inductive elements, $$k = \frac{\left | L_{mn} \right |}{\sqrt{L_m L_n}}$$, where $$L_m$$ and $$L_n$$ are their self inductances, and $$L_{mn}$$ is their mutual inductance. "Coupling Factor" is the ratio of an electromagnetic quantity, usually voltage or current, appearing at a specified location of a given circuit to the corresponding quantity at a specified location in the circuit from which energy is transferred by coupling. k Coupling Factor http://en.wikipedia.org/wiki/Cross_section_(physics) http://www.iso.org/iso/catalogue_detail?csnumber=31895 "Cross-section" is used to express the likelihood of interaction between particles. For a specified target particle and for a specified reaction or process produced by incident charged or uncharged particles of specified type and energy, it is the mean number of such reactions or processes divided by the incident-particle fluence. σ Cross-section A Cross-sectional Area $$A^3 \cdot s^7/kg^2 \cdot m$$ $$I^3 \cdot T^7/L \cdot M^2$$ Cubic Electric Dipole Moment per Square Energy $$cubic-exp-coef$$ http://www.iso.org/iso/catalogue_detail?csnumber=31890 $$\alpha_V = \frac{1}{V} \; \frac{dV}{dT}$$, where $$V$$ is $$volume$$ and $$T$$ is thermodynamic temperature. $$\alpha_v$$ Cubic Expansion Coefficient http://en.wikipedia.org/wiki/Curie_temperature http://www.iso.org/iso/catalogue_detail?csnumber=31897 "Curie Temperature" is the critical thermodynamic temperature of a ferromagnet. T_C Curie Temperature http://dbpedia.org/resource/Currency http://en.wikipedia.org/wiki/Currency In economics, currency is a generally accepted medium of exchange. These are usually the coins and banknotes of a particular government, which comprise the physical aspects of a nation's money supply. The other part of a nation's money supply consists of bank deposits (sometimes called deposit money), ownership of which can be transferred by means of cheques, debit cards, or other forms of money transfer. Deposit money and currency are money in the sense that both are acceptable as a means of payment. Currency $$current-linkage$$ http://www.electropedia.org/iev/iev.nsf/display?openform&ievref=121-11-60 $$\Theta$$ "Current Linkage" is the net electric current through a surface delimited by a closed loop. Current Linkage The canonical example of extrinsic curvature is that of a circle, which has curvature equal to the inverse of its radius everywhere. Smaller circles bend more sharply, and hence have higher curvature. The curvature of a smooth curve is defined as the curvature of its osculating circle at each point. The osculating circle of a sufficiently smooth plane curve at a given point on the curve is the circle whose center lies on the inner normal line and whose curvature is the same as that of the given curve at that point. This circle is tangent to the curve at the given point. The magnitude of curvature at points on physical curves can be measured in $$diopters$$ (also spelled $$dioptre$$) — this is the convention in optics. http://dbpedia.org/resource/Curvature http://en.wikipedia.org/wiki/Curvature The canonical example of extrinsic curvature is that of a circle, which has curvature equal to the inverse of its radius everywhere. Smaller circles bend more sharply, and hence have higher curvature. The curvature of a smooth curve is defined as the curvature of its osculating circle at each point. The osculating circle of a sufficiently smooth plane curve at a given point on the curve is the circle whose center lies on the inner normal line and whose curvature is the same as that of the given curve at that point. This circle is tangent to the curve at the given point. That is, given a point P on a smooth curve C, the curvature of C at P is defined to be 1/R where R is the radius of the osculating circle of C at P. The magnitude of curvature at points on physical curves can be measured in diopters (also spelled dioptre) — this is the convention in optics. [Wikipedia], Curvature http://en.wikipedia.org/wiki/Curvature http://www.iso.org/iso/catalogue_detail?csnumber=43012 $$\kappa = \frac{1}{\rho}$$, where $$\rho$$ is the radius of the curvature. $$\kappa$$ In mathematics "Curvature" is the amount by which a geometric object deviates from being flat, or straight in the case of a line, but this is defined in different ways depending on the context. Curvature http://en.wikipedia.org/wiki/Electron_cyclotron_resonance http://www.iso.org/iso/catalogue_detail?csnumber=31895 $$\omega_c = \frac{\left | q \right |}{m}B$$, where $$q$$ is the electric charge, $$m$$ is its mass, and $$B$$ is the magnetic flux density. $$\omega_c$$ The "Cyclotron Angular Frequency" describes angular momentum vector precession about the external field axis with an angular frequency. Larmor Angular Frequency $$\bigtriangleup v$$ The change in translational velocity including all losses for a propulsive system or module. Delta-V losses include, but are not limited to, gravity losses and steering losses. http://en.wikipedia.org/wiki/Delta-v Delta-V Mass of a system without the propellants, pressurants, reserve or residual fluids, personnel and personnel provisions, and cargo. Dry Mass http://dbpedia.org/resource/Data_rate The frequency derived from the period of time required to transmit one bit. This represents the amount of data transferred per second by a communications channel or a computing or storage device. Data rate is measured in units of bits per second (written "b/s" or "bps"), bytes per second (Bps), or baud. When applied to data rate, the multiplier prefixes "kilo-", "mega-", "giga-", etc. (and their abbreviations, "k", "M", "G", etc.) always denote powers of 1000. For example, 64 kbps is 64,000 bits per second. This contrasts with units of storage which use different prefixes to denote multiplication by powers of 1024, for example 1 kibibit = 1024 bits. Data Rate http://en.wikipedia.org/wiki/Debye–Waller_factor http://www.iso.org/iso/catalogue_detail?csnumber=31897 $$u = R - R_0$$, where $$R$$ is the particle position vector and $$R_0$$ is the equilibrium position vector of a particle. "Debye-Waller Factor" (DWF), named after Peter Debye and Ivar Waller, is used in condensed matter physics to describe the attenuation of x-ray scattering or coherent neutron scattering caused by thermal motion. Also, a factor by which the intensity of a diffraction line is reduced because of the lattice vibrations. D, B Debye-Waller Factor http://lamp.tu-graz.ac.at/~hadley/ss1/phonons/table/dosdebye.html http://www.iso.org/iso/catalogue_detail?csnumber=31897 $$\omega_b$$ "Debye Angular Frequency" is the cut-off angular frequency in the Debye model of the vibrational spectrum of a solid. Debye Angular Frequency http://www.iso.org/iso/catalogue_detail?csnumber=31897 "Debye Angular Wavenumber" is the cut-off angular wavenumber in the Debye model of the vibrational spectrum of a solid. q_D Debye Angular Wavenumber http://en.wikipedia.org/wiki/Debye_model http://www.iso.org/iso/catalogue_detail?csnumber=31897 $$\Theta_D = \frac{\hbar\omega_D}{k}$$, where $$k$$ is the Boltzmann constant, $$\hbar$$ is the reduced Planck constant, and $$\omega_D$$ is the Debye angular frequency. $$\Theta_D$$ "Debye Temperature" is the temperature at which the highest-frequency mode (and hence all modes) are excited. Debye Temperature http://en.wikipedia.org/wiki/Exponential_decay http://www.britannica.com/EBchecked/topic/154945/decay-constant http://www.iso.org/iso/catalogue_detail?csnumber=31895 Relative variation $$\frac{dN}{N}$$ of the number $$N$$ of atoms or nuclei in a system, due to spontaneous emission from these atoms or nuclei during an infinitesimal time interval, divided by its duration $$dt$$, thus $$\lambda = -\frac{1}{N}\frac{dN}{dt}$$. $$\lambda$$ The "Decay Constant" is the proportionality between the size of a population of radioactive atoms and the rate at which the population decreases because of radioactive decay. Decay Constant http://dbpedia.org/resource/Faraday_constant http://en.wikipedia.org/wiki/Dissociation_(chemistry) http://www.iso.org/iso/catalogue_detail?csnumber=31894 $$\alpha$$ The "Degree of Dissociation" is the fraction of original solute molecules that have dissociated. Degree of Dissociation The mass density or density of a material is defined as its mass per unit volume. The symbol most often used for density is $$\rho$$. Mathematically, density is defined as mass divided by volume: $$\rho = m/V$$, where $$\rho$$ is the density, $$m$$ is the mass, and $$V$$ is the volume. In some cases, density is also defined as its weight per unit volume, although this quantity is more properly called specific weight. $$M/L^3$$ $$kg/m^3$$ http://dbpedia.org/resource/Density http://en.wikipedia.org/wiki/Density $$\rho = m/V$$, where $$\rho$$ is the density, $$m$$ is the mass, and $$V$$ is the volume. $$\rho$$ belongs to SOQ-ISO Density $$\rho_c$$ Density In Combustion Chamber http://en.wikipedia.org/wiki/Density_of_states http://www.iso.org/iso/catalogue_detail?csnumber=31897 "Density of States" is the number of vibrational modes in an infinitesimal interval of angular frequency divided by the range of that interval and by volume. g Density of states $$\rho$$ Density Of The Exhaust Gases Depth typically refers to the vertical measure of length from the surface of a liquid. Depth http://www.iso.org/iso/catalogue_detail?csnumber=31890 "Dew Point Temperature" is the temperature at which vapour in air reaches saturation. T_d Dew Point Temperature http://dbpedia.org/resource/Diameter http://en.wikipedia.org/wiki/Diameter http://www.iso.org/iso/catalogue_detail?csnumber=43012 $$d = 2r$$, where $$r$$ is the radius of the circle. In classical geometry, the "Diameter" of a circle is any straight line segment that passes through the center of the circle and whose endpoints lie on the circle. d Diameter http://www.oxfordreference.com/view/10.1093/acref/9780199549351.001.0001/acref-9780199549351-e-1162 The pressure of blood in the arteries which rises to a maximum as blood is pumped out by the left ventricle (systole) and drops to a minimum in diastole. The systolic/diastolic pressure is normally ~120/80 mmHg in a young adult. Diastolic Blood Pressure http://encyclopedia2.thefreedictionary.com/diffusion+area http://www.iso.org/iso/catalogue_detail?csnumber=31895 "Diffusion Area" in an infinite homogenous medium, is one-sixth of the mean square distance between the point where a neutron enters a specified class and the point where it leaves that class. L^2 Diffusion Area http://en.wikipedia.org/wiki/Mass_diffusivity http://www.iso.org/iso/catalogue_detail?csnumber=31894 $$C_B \left \langle \nu_B \right \rangle = -D grad C_B$$, where $$C_B$$ the local molecular concentration of substance $$B$$ in the mixture and $$\left \langle \nu_B \right \rangle$$ is the local average velocity of the molecules of $$B$$. The "Diffusion Coefficient" is a proportionality constant between the molar flux due to molecular diffusion and the gradient in the concentration of the species (or the driving force for diffusion). Diffusivity is encountered in Fick's law and numerous other equations of physical chemistry. D Diffusion Coefficient m http://en.wikipedia.org/wiki/Mass_diffusivity $$D_\varphi = -\frac{J_x}{\frac{\partial d\varphi}{\partial dx}}$$, where $$J_x$$ is the $$x-component$$ of the particle current and $$\varphi$$ is the particle fluence rate. http://www.iso.org/iso/catalogue_detail?csnumber=31895 The "Diffusion Coefficient for Fluence Rate" is a proportionality constant between the . Dᵩ Diffusion Coefficient for Fluence Rate http://encyclopedia2.thefreedictionary.com/diffusion+length $$L = \sqrt{L^2}$$, where $$L^2$$ is the diffusion area. http://www.iso.org/iso/catalogue_detail?csnumber=31895 "Diffusion Length" is the average distance traveled by a particle, or a thermal neutron in a nuclear reactor, from the point at which it is formed to the point at which it is absorbed. L Diffusion Length In dimensional analysis, a dimensionless quantity or quantity of dimension one is a quantity without an associated physical dimension. It is thus a "pure" number, and as such always has a dimension of 1. Dimensionless quantities are widely used in mathematics, physics, engineering, economics, and in everyday life (such as in counting). Numerous well-known quantities, such as $$\pi$$, $$\epsilon$$, and $$\psi$$, are dimensionless. By contrast, non-dimensionless quantities are measured in units of length, area, time, etc. Dimensionless quantities are often defined as products or ratios of quantities that are not dimensionless, but whose dimensions cancel out when their powers are multiplied. $$U$$  http://dbpedia.org/resource/Dimensionless_quantity http://en.wikipedia.org/wiki/Dimensionless_quantity U Dimensionless Dimensionless Ratio http://en.wikipedia.org/wiki/Displacement_(vector) http://www.iso.org/iso/catalogue_detail?csnumber=43012 $$\Delta r = R_f - R_i$$, where $$R_f$$ is the final position and $$R_i$$ is the initial position. $$\Delta r$$ "Displacement" is the shortest distance from the initial to the final position of a point P. Displacement http://en.wikipedia.org/wiki/Displacement_current http://www.iso.org/iso/home/store/catalogue_tc/catalogue_detail.htm?csnumber=31891 $$I_D= \int_S J_D \cdot e_n dA$$, over a surface $$S$$, where $$J_D$$ is displacement current density and $$e_n dA$$ is the vector surface element. "Displacement Current" is a quantity appearing in Maxwell's equations that is defined in terms of the rate of change of electric displacement field. Displacement current has the units of electric current density, and it has an associated magnetic field just as actual currents do. However it is not an electric current of moving charges, but a time-varying electric field. In materials, there is also a contribution from the slight motion of charges bound in atoms, dielectric polarization. I_D Displacement Current $$\textbf{Displacement Current Density}$$ is the time rate of change of the $$\textit{Electric Flux Density}$$. This is a measure of how quickly the electric field changes if we observe it as a function of time. This is different than if we look at how the electric field changes spatially, that is, over a region of space for a fixed amount of time. http://dbpedia.org/resource/Electric_flux http://www.iso.org/iso/home/store/catalogue_tc/catalogue_detail.htm?csnumber=31891 http://www.maxwells-equations.com/math/partial-electric-flux.php $$J_D = \frac{\partial D}{\partial t}$$, where $$D$$ is electric flux density and $$t$$ is time. $$J_D$$ Displacement Current Density http://en.wikipedia.org/wiki/Displacement $$u = R - R_0$$, where $$R$$ is the particle position vector and $$R_0$$ is the equilibrium position vector of a particle. http://www.iso.org/iso/catalogue_detail?csnumber=31897 "Displacement Vector of Ion" is the . u Displacement Vector of Ion http://en.wikipedia.org/wiki/Dissipation_factor $$\delta = \frac{P_d}{P_i}$$, where $$P_d$$ is the dissipated sound power, and $$P_i$$ is the incident sound power. $$\delta$$ Dissipance, or dissipation factor for sound power, is the ratio of dissipated sound power to incident sound power. The dissipation factor (DF) is a measure of loss-rate of energy of a mode of oscillation (mechanical, electrical, or electromechanical) in a dissipative system. It is the reciprocal of quality factor, which represents the quality of oscillation. belongs to SOQ-ISO Dissipance http://en.wikipedia.org/wiki/Distance http://www.iso.org/iso/catalogue_detail?csnumber=43012 "Distance" is a numerical description of how far apart objects are. d Distance s Distance Traveled During a Burn http://www.iso.org/iso/catalogue_detail?csnumber=31897 "Donor Density" is the number per volume of donor levels. n_d Donor Density http://en.wikipedia.org/wiki/Ionization_energy http://www.iso.org/iso/catalogue_detail?csnumber=31897 "Donor Ionization Energy" is the ionization energy of a donor. E_d Donor Ionization Energy "Dose Equivalent} (former), or \textit{Equivalent Absorbed Radiation Dose}, usually shortened to \textit{Equivalent Dose", is a computed average measure of the radiation absorbed by a fixed mass of biological tissue, that attempts to account for the different biological damage potential of different types of ionizing radiation. The equivalent dose to a tissue is found by multiplying the absorbed dose, in gray, by a dimensionless "quality factor" $$Q$$, dependent upon radiation type, and by another dimensionless factor $$N$$, dependent on all other pertinent factors. N depends upon the part of the body irradiated, the time and volume over which the dose was spread, even the species of the subject. http://dbpedia.org/resource/Equivalent_dose http://en.wikipedia.org/wiki/Equivalent_dose http://www.iso.org/iso/catalogue_detail?csnumber=31895 At the point of interest in tissue, $$H = DQ$$, where $$D$$ is the absorbed dose and $$Q$$ is the quality factor at that point. H Dose Equivalent http://en.wikipedia.org/wiki/Equivalent_dose http://www.iso.org/iso/catalogue_detail?csnumber=31895 "Dose Equivalent Quality Factor" is a factor in the caculation and measurement of dose equivalent, by which the absorbed dose is to be weighted in order to account for different biological effectiveness of radiations, for radiation protection purposes. Q Dose Equivalent Quality Factor In fluid dynamics, the drag coefficient is a dimensionless quantity that is used to quantify the drag or resistance of an object in a fluid environment such as air or water. C_D Drag Coefficient In fluid dynamics, drag refers to forces which act on a solid object in the direction of the relative fluid flow velocity. Unlike other resistive forces such as dry friction, which is nearly independent of velocity, drag forces depend on velocity. Drag forces always decrease fluid velocity relative to the solid object in the fluid's path. D or F_D Drag Force Dry measures are units of volume used to measure bulk commodities which are not gas or liquid. They are typically used in agriculture, agronomy, and commodity markets to measure grain, dried beans, and dried and fresh fruit; formerly also salt pork and fish. They are also used in fishing for clams, crabs, etc. and formerly for many other substances (for example coal, cement, lime) which were typically shipped and delivered in a standardized container such as a barrel. In the original metric system, the unit of dry volume was the stere, but this is not part of the modern metric system; the liter and the cubic meter ($$m^{3}$$) are now used. However, the stere is still widely used for firewood. http://en.wikipedia.org/wiki/Dry_measure Dry Volume http://dbpedia.org/resource/Friction http://en.wikipedia.org/wiki/Friction http://www.iso.org/iso/catalogue_detail?csnumber=31889 Kinetic (or dynamic) friction occurs when two objects are moving relative to each other and rub together (like a sled on the ground). Dynamic Friction http://dbpedia.org/resource/Friction http://en.wikipedia.org/wiki/Friction http://www.iso.org/iso/catalogue_detail?csnumber=31889 $$\mu = \frac{F}{N}$$, where $$F$$ is the tangential component of the contact force and $$N$$ is the normal component of the contact force between two sliding bodies. $$\mu$$ Kinetic (or dynamic) friction occurs when two objects are moving relative to each other and rub together (like a sled on the ground). Dynamic Friction Coefficient Dynamic Pressure (indicated with q, or Q, and sometimes called velocity pressure) is the quantity defined by: $$q = 1/2 * \rho v^{2}$$, where (using SI units), $$q$$ is dynamic pressure in $$pascals$$, $$\rho$$ is fluid density in $$kg/m^{3}$$ (for example, density of air) and $$v$$ is fluid velocity in $$m/s$$. http://dbpedia.org/resource/Dynamic_pressure q Dynamic Pressure $$M/L \cdot T$$ $$kg/m \cdot s$$ http://dictionary.reference.com/browse/dynamic+viscosity http://www.iso.org/iso/catalogue_detail?csnumber=31889 $$\tau_{xz} = \eta\frac{dv_x}{dz}$$, where $$\tau_{xz}$$ is shear stress in a fluid moving with a velocity gradient $$\frac{dv_x}{dz}$$ perpendicular to the plane of shear. $$\mu$$ A measure of the molecular frictional resistance of a fluid as calculated using Newton's law. Dynamic Viscosity V_o Earth Closest Approach Vehicle Velocity $$\varepsilon$$ The orbital eccentricity of an astronomical object is a parameter that determines the amount by which its orbit around another body deviates from a perfect circle. In a two-body problem with inverse-square-law force, every orbit is a Kepler orbit. The eccentricity of this Kepler orbit is a positive number that defines its shape. Eccentricity Of Orbit The velocity of an exhaust stream after reduction by effects such as friction, non-axially directed flow, and pressure differences between the inside of the rocket and its surroundings. The effective exhaust velocity is one of two factors determining the thrust, or accelerating force, that a rocket can develop, the other factor being the quantity of reaction mass expelled from the rocket in unit time. In most cases, the effective exhaust velocity is close to the actual exhaust velocity. v_{e} Effective Exhaustvelocity http://en.wikipedia.org/wiki/Effective_mass_(solid-state_physics) http://www.iso.org/iso/catalogue_detail?csnumber=31897 $$m^* = \hbar^2k(\frac{d\varepsilon}{dk})$$, where $$\hbar$$ is the reduced Planck constant, $$k$$ is the wavenumber, and $$\varepsilon$$ is the energy of the electron. "Effective Mass" is used in the motional equation for electrons in solid state bodies, depending on the wavenumber and corresponding to its velocity and energy level. m^* Effective Mass http://en.wikipedia.org/wiki/Nuclear_chain_reaction#Effective_neutron_multiplication_factor http://www.iso.org/iso/catalogue_detail?csnumber=31895 The "Effective Multiplication Factor" is the multiplication factor for a finite medium. k_{eff} Effective Multiplication Factor http://en.wikipedia.org/wiki/Deformation_(mechanics) http://www.iso.org/iso/catalogue_detail?csnumber=31889 $$\eta = \frac{P_{out}}{P_{in}}$$, where $$P_{out}$$ is the output power and $$P_{in}$$ is the input power. $$\eta$$ Efficiency is the ratio of output power to input power. Efficiency Given two atomic states of energy $$E_j$$ and $$E_k$$. Let $$E_j > E_k$$. Assume the atom is bathed in radiation of energy density $$u(w)$$. Transitions between these states can take place in three different ways. Spontaneous, induced/stimulated emission, and induced absorption. $$A_jk$$ represents the Einstein transition probability for spontaneous emission. $$\frac{-dN_j}{dt} = A_jkN_j$$, where $$-dN_j$$ is the number of molecules spontaneously leaving the state j for the state k during a time interval of duration $$dt$$, $$N_j$$ is the number of molecules in the state j, and $$E_j > E_k$$. A_jkN_j Einstein Transition Probability "Electric Charge" is a fundamental conserved property of some subatomic particles, which determines their electromagnetic interaction. Electrically charged matter is influenced by, and produces, electromagnetic fields. The electric charge on a body may be positive or negative. Two positively charged bodies experience a mutual repulsive force, as do two negatively charged bodies. A positively charged body and a negatively charged body experience an attractive force. Electric charge is carried by discrete particles and can be positive or negative. The sign convention is such that the elementary electric charge $$e$$, that is, the charge of the proton, is positive. The SI derived unit of electric charge is the coulomb. $$A \cdot s$$ $$I \cdot T$$ http://en.wikipedia.org/wiki/Electric_charge http://en.wikipedia.org/wiki/Electric_charge?oldid=492961669 http://www.iso.org/iso/home/store/catalogue_tc/catalogue_detail.htm?csnumber=31891 $$dQ = Idt$$, where $$I$$ is electric current. Q Electric Charge $$charge-density$$ http://en.wikipedia.org/wiki/Charge_density http://www.iso.org/iso/home/store/catalogue_tc/catalogue_detail.htm?csnumber=31891 http://www.maxwells-equations.com/pho/charge-density.php $$\rho = \frac{dQ}{dV}$$, where $$Q$$ is electric charge and $$V$$ is Volume. $$\rho$$ In electromagnetism, charge density is a measure of electric charge per unit volume of space, in one, two or three dimensions. More specifically: the linear, surface, or volume charge density is the amount of electric charge per unit length, surface area, or volume, respectively. Electric Charge Density In electromagnetism, charge density is a measure of electric charge per unit volume of space, in one, two or three dimensions. More specifically: the linear, surface, or volume charge density is the amount of electric charge per unit length, surface area, or volume, respectively. The respective SI units are $$C \cdot$$, $$m^{-1}$$, $$C \cdot m^{-2}$$ or $$C \cdot m^{-3}$$. $$A \cdot s/m$$ $$I \cdot T/L$$ http://en.wikipedia.org/wiki/Charge_density $$\lambda$$ Electric Charge Line Density $$linear-charge-density$$ http://en.wikipedia.org/wiki/Charge_density http://www.iso.org/iso/home/store/catalogue_tc/catalogue_detail.htm?csnumber=31891 $$\rho_l = \frac{dQ}{dl}$$, where $$Q$$ is electric charge and $$l$$ is length. $$\rho_l$$ $$\tau$$ In electromagnetism, charge density is a measure of electric charge per unit volume of space, in one, two or three dimensions. More specifically: the linear, surface, or volume charge density is the amount of electric charge per unit length, surface area, or volume, respectively. Electric Charge Linear Density "Electric Charge Per Amount Of Substance" is the charge assocated with a given amount of substance. Un the ISO and SI systems this is $$1 mol$$. $$A \cdot s/mol$$ $$I \cdot T/M$$ Electric charge per amount of substance In electromagnetism, charge density is a measure of electric charge per unit volume of space, in one, two or three dimensions. More specifically: the linear, surface, or volume charge density is the amount of electric charge per unit length, surface area, or volume, respectively. The respective SI units are $$C \cdot m^{-1}$$, $$C \cdot m^{-2}$$ or $$C \cdot m^{-3}$$. $$A \cdot s/m^2$$ $$I \cdot T/L^2$$ http://en.wikipedia.org/wiki/Charge_density $$\sigma$$ Electric charge per area "Electric Charge Per Mass" is the charge associated with a specific mass of a substance. In the SI and ISO systems this is $$1 kg$$. $$A \cdot s/kg$$ $$I \cdot T/M$$ Electric Charge Per Mass $$surface-charge-density$$ http://en.wikipedia.org/wiki/Charge_density http://www.iso.org/iso/home/store/catalogue_tc/catalogue_detail.htm?csnumber=31891 $$\rho_A = \frac{dQ}{dA}$$, where $$Q$$ is electric charge and $$A$$ is Area. $$\rho_A$$ In electromagnetism, charge density is a measure of electric charge per unit volume of space, in one, two or three dimensions. More specifically: the linear, surface, or volume charge density is the amount of electric charge per unit length, surface area, or volume, respectively. Electric Charge Surface Density In electromagnetism, charge density is a measure of electric charge per unit volume of space, in one, two or three dimensions. More specifically: the linear, surface, or volume charge density is the amount of electric charge per unit length, surface area, or volume, respectively. The respective SI units are $$C \cdot m^{-1}$$, $$C \cdot m^{-2}$$ or $$C \cdot m^{-3}$$. $$A \cdot s/m^3$$ $$I \cdot T/L^3$$ http://en.wikipedia.org/wiki/Charge_density $$\rho$$ Electric Charge Volume Density "Electric Conductivity} or \textit{Specific Conductance" is a measure of a material's ability to conduct an electric current. When an electrical potential difference is placed across a conductor, its movable charges flow, giving rise to an electric current. The conductivity $$\sigma$$ is defined as the ratio of the electric current density $$J$$ to the electric field $$E$$: $$J = \sigma E$$. In isotropic materials, conductivity is scalar-valued, however in general, conductivity is a tensor-valued quantity. $$A^2 \cdot s^3/kg \cdot m^2$$ $$I^2 \cdot T^3/L^2 \cdot M$$ $$\sigma$$ Electric Conductivity $$A$$ $$I$$ http://dbpedia.org/resource/Electric_current http://www.iso.org/iso/home/store/catalogue_tc/catalogue_detail.htm?csnumber=31891 "Electric Current" is the flow (movement) of electric charge. The amount of electric current through some surface, for example, a section through a copper conductor, is defined as the amount of electric charge flowing through that surface over time. Current is a scalar-valued quantity. Electric current is one of the base quantities in the International System of Quantities, ISQ, on which the International System of Units, SI, is based. I Electric Current "Electric Current Density" is a measure of the density of flow of electric charge; it is the electric current per unit area of cross section. Electric current density is a vector-valued quantity. Electric current, $$I$$, through a surface $$S$$ is defined as $$I = \int_S J \cdot e_n dA$$, where $$e_ndA$$ is the vector surface element. $$A/m^2$$ $$I/L^2$$ http://dbpedia.org/resource/Current_density http://maxwells-equations.com/density/current.php http://www.iso.org/iso/home/store/catalogue_tc/catalogue_detail.htm?csnumber=31891 $$J = \rho v$$, where $$\rho$$ is electric current density and $$v$$ is volume. J Electric Current Density $$A$$ $$I/U$$ Electric Current per Angle $$A \cdot s^3/kg \cdot m^2$$ $$I \cdot T^3/L^2 \cdot M$$ Electric Current per Unit Energy $$A/m$$ $$I/L$$ Electric Current per Unit Length "Electric Current per Unit Temperature" is used to express how a current is subject to temperature. Originally used in Wien's Law to describe phenomena related to filaments. One use today is to express how a current generator derates with temperature. Electric Current per Unit Temperature http://en.wikipedia.org/wiki/Phasor_(electronics) http://www.electropedia.org/iev/iev.nsf/display?openform&ievref=131-11-26 http://www.iso.org/iso/home/store/catalogue_tc/catalogue_detail.htm?csnumber=31891 When $$i = \hat{I} \cos{(\omega t + \alpha)}$$, where $$i$$ is the electric current, $$\omega$$ is angular frequence, $$t$$ is time, and $$\alpha$$ is initial phase, then $$\underline{I} = Ie^{ja}$$. $$\underline{I}$$ "Electric Current Phasor" is a representation of current as a sinusoidal integral quantity using a complex quantity whose argument is equal to the initial phase and whose modulus is equal to the root-mean-square value. A phasor is a constant complex number, usually expressed in exponential form, representing the complex amplitude (magnitude and phase) of a sinusoidal function of time. Phasors are used by electrical engineers to simplify computations involving sinusoids, where they can often reduce a differential equation problem to an algebraic one. Electric Current Phasor $$A \cdot m \cdot s$$ $$I \cdot L \cdot T$$ http://en.wikipedia.org/wiki/Electric_dipole_moment http://www.iso.org/iso/home/store/catalogue_tc/catalogue_detail.htm?csnumber=31891 http://www.iso.org/iso/catalogue_detail?csnumber=31894 $$E_p = -p \cdot E$$, where $$E_p$$ is the interaction energy of the molecule with electric dipole moment $$p$$ and an electric field with electric field strength $$E$$. $$p = q(r_+ - r_i)$$, where $$r_+$$ and $$r_-$$ are the position vectors to carriers of electric charge $$a$$ and $$-q$$, respectively. "Electric Dipole Moment" is a measure of the separation of positive and negative electrical charges in a system of (discrete or continuous) charges. It is a vector-valued quantity. If the system of charges is neutral, that is if the sum of all charges is zero, then the dipole moment of the system is independent of the choice of a reference frame; however in a non-neutral system, such as the dipole moment of a single proton, a dependence on the choice of reference point arises. In such cases it is conventional to choose the reference point to be the center of mass of the system or the center of charge, not some arbitrary origin. This convention ensures that the dipole moment is an intrinsic property of the system. The electric dipole moment of a substance within a domain is the vector sum of electric dipole moments of all electric dipoles included in the domain. p Electric Dipole Moment In a dielectric material the presence of an electric field E causes the bound charges in the material (atomic nuclei and their electrons) to slightly separate, inducing a local electric dipole moment. The Electric Displacement Field, $$D$$, is a vector field that accounts for the effects of free charges within such dielectric materials. This describes also the charge density on an extended surface that could be causing the field. http://www.iso.org/iso/home/store/catalogue_tc/catalogue_detail.htm?csnumber=31891 http://www.oxfordreference.com/view/10.1093/acref/9780199233991.001.0001/acref-9780199233991-e-895 $$D = \epsilon_0 E + P$$, where $$\epsilon_0$$ is the electric constant, $$E$$ is electric field strength, and $$P$$ is electric polarization. D Electric Displacement D Electric Displacement Field $$L \cdot M/I \cdot T^3$$ $$kg \cdot m/A \cdot s^3$$ http://dbpedia.org/resource/Electric_field $$E$$ http://en.wikipedia.org/wiki/Electric_field The space surrounding an electric charge or in the presence of a time-varying magnetic field has a property called an electric field. This electric field exerts a force on other electrically charged objects. In the idealized case, the force exerted between two point charges is inversely proportional to the square of the distance between them. (Coulomb's Law). Electric Field $$\textbf{Electric Field Strength}$$ is the magnitude and direction of an electric field, expressed by the value of $$E$$, also referred to as $$\color{indigo} {\textit{electric field intensity}}$$ or simply the electric field. $$kg \cdot m/A \cdot s^3$$ http://www.iso.org/iso/home/store/catalogue_tc/catalogue_detail.htm?csnumber=31891 $$\mathbf{E} = \mathbf{F}/q$$, where $$\mathbf{F}$$ is force and $$q$$ is electric charge, of a test particle at rest. $$\mathbf{E}$$ E Electric Field Strength $$L^3 \cdot M/I \cdot T^3$$ $$kg \cdot m^3/A \cdot s^3$$ http://dbpedia.org/resource/Electric_flux $$electirc-flux$$ http://www.iso.org/iso/home/store/catalogue_tc/catalogue_detail.htm?csnumber=31891 $$\Psi = \int_S D \cdot e_n dA$$, over a surface $$S$$, where $$D$$ is electric flux density and $$e_n dA$$ is the vector surface element. $$\Psi$$ "Electric Flux" through an area is defined as the electric field multiplied by the area of the surface projected in a plane perpendicular to the field. Electric Flux is a scalar-valued quantity. Electric Flux $$\textbf{Electric Flux Density}$$, also referred to as $$\textit{Electric Displacement}$$, is related to electric charge density by the following equation: $$\text{div} \; D = \rho$$, where $$\text{div}$$ denotes the divergence. http://dbpedia.org/resource/Electric_flux http://www.iso.org/iso/home/store/catalogue_tc/catalogue_detail.htm?csnumber=31891 $$\mathbf{D} = \epsilon_0 E + P$$, where $$\epsilon_0$$ is the electric constant, $$\mathbf{E}$$ is electric field strength, and $$P$$ is electric polarization. $$\mathbf{D}$$ Electric Flux Density http://en.wikipedia.org/wiki/Polarizability http://www.iso.org/iso/catalogue_detail?csnumber=31894 $$\alpha_{i,j} = \frac{\partial p_i}{\partial E_j}$$, where $$p_i$$ is the cartesian component along the $$i-axis$$ of the electric dipole moment induced by the applied electric field strength acting on the molecule, and $$E_j$$ is the component along the $$j-axis$$ of this electric field strength. $$\alpha$$ "Electric Polarizability" is the relative tendency of a charge distribution, like the electron cloud of an atom or molecule, to be distorted from its normal shape by an external electric field, which is applied typically by inserting the molecule in a charged parallel-plate capacitor, but may also be caused by the presence of a nearby ion or dipole. Electric Polarizability http://www.britannica.com/EBchecked/topic/182690/electric-polarization http://www.iso.org/iso/home/store/catalogue_tc/catalogue_detail.htm?csnumber=31891 $$P =\frac{dp}{dV}$$, where $$p$$ is electic charge density and $$V$$ is volume. "Electric Polarization" is the relative shift of positive and negative electric charge in opposite directions within an insulator, or dielectric, induced by an external electric field. Polarization occurs when an electric field distorts the negative cloud of electrons around positive atomic nuclei in a direction opposite the field. This slight separation of charge makes one side of the atom somewhat positive and the opposite side somewhat negative. In some materials whose molecules are permanently polarized by chemical forces, such as water molecules, some of the polarization is caused by molecules rotating into the same alignment under the influence of the electric field. One of the measures of polarization is electric dipole moment, which equals the distance between the slightly shifted centres of positive and negative charge multiplied by the amount of one of the charges. Polarization P in its quantitative meaning is the amount of dipole moment p per unit volume V of a polarized material, P = p/V. P Electric Polarization The Electric Potential is a scalar valued quantity associated with an electric field. The electric potential $$\phi(x)$$ at a point, $$x$$, is formally defined as the line integral of the electric field taken along a path from x to the point at infinity. If the electric field is static, that is time independent, then the choice of the path is arbitrary; however if the electric field is time dependent, taking the integral a different paths will produce different results. http://www.iso.org/iso/home/store/catalogue_tc/catalogue_detail.htm?csnumber=31891 http://www.iso.org/iso/catalogue_detail?csnumber=43012 $$-\textbf{grad} \; V = E + \frac{\partial A}{\partial t}$$, where $$E$$ is electric field strength, $$A$$ is magentic vector potential and $$t$$ is time. $$\phi$$ V Electric Potential