Physical coefficient is an important number that characterizes some physical property of a technical or scientific object under specified conditions. A coefficient also has a scientific reference which is the reliance on force.
Stoichiometric coefficient of a chemical compound
To find the coefficient of a
chemical compound
A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one element ...
, you must balance the elements involved in it. For example, water:
H
2O.
It just so happens that hydrogen (H) and oxygen (O) are both
diatomic
Diatomic molecules () are molecules composed of only two atoms, of the same or different chemical elements. If a diatomic molecule consists of two atoms of the same element, such as hydrogen () or oxygen (), then it is said to be homonuclear mol ...
molecules, thus we have H
2 and O
2. To form water, one of the O atoms breaks off from the O
2 molecule and react with the H
2 compound to form H
2O. But, there is one oxygen atom left. It reacts with another H
2 molecule. Since it took two of each atom to balance the compound, we put the coefficient 2 in front of H
2O:
2 H
2O.
The total reaction is thus 2 H
2 + O
2 → 2 H
2O.
Examples of physical coefficients
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Coefficient of thermal expansion
Thermal expansion is the tendency of matter to increase in length, area, or volume, changing its size and density, in response to an increase in temperature (usually excluding phase transitions).
Substances usually contract with decreasing temp ...
'' (
thermodynamics
Thermodynamics is a branch of physics that deals with heat, Work (thermodynamics), work, and temperature, and their relation to energy, entropy, and the physical properties of matter and radiation. The behavior of these quantities is governed b ...
) (dimensionless) - Relates the change in temperature to the change in a material's dimensions.
# ''
Partition coefficient
In the physical sciences, a partition coefficient (''P'') or distribution coefficient (''D'') is the ratio of concentrations of a chemical compound, compound in a mixture of two immiscible solvents at partition equilibrium, equilibrium. This rati ...
'' (''K
D'') (
chemistry
Chemistry is the scientific study of the properties and behavior of matter. It is a physical science within the natural sciences that studies the chemical elements that make up matter and chemical compound, compounds made of atoms, molecules a ...
) - The ratio of concentrations of a compound in two phases of a mixture of two immiscible solvents at equilibrium.
# ''
Hall coefficient
The Hall effect is the production of a potential difference (the Hall voltage) across an electrical conductor that is transverse to an electric current in the conductor and to an applied magnetic field perpendicular to the current. It was d ...
'' (electrical physics) - Relates a magnetic field applied to an element to the voltage created, the amount of current and the element thickness. It is a characteristic of the material from which the conductor is made.
# ''
Lift coefficient
In fluid dynamics, the lift coefficient () is a dimensionless quantity that relates the lift generated by a lifting body to the fluid density around the body, the fluid velocity and an associated reference area. A lifting body is a foil or a co ...
'' (''C
L'' or ''C
Z'') (
aerodynamics
Aerodynamics () is the study of the motion of atmosphere of Earth, air, particularly when affected by a solid object, such as an airplane wing. It involves topics covered in the field of fluid dynamics and its subfield of gas dynamics, and is an ...
) (dimensionless) - Relates the lift generated by an
airfoil
An airfoil (American English) or aerofoil (British English) is a streamlined body that is capable of generating significantly more Lift (force), lift than Drag (physics), drag. Wings, sails and propeller blades are examples of airfoils. Foil (fl ...
with the
dynamic pressure
In fluid dynamics, dynamic pressure (denoted by or and sometimes called velocity pressure) is the quantity defined by:Clancy, L.J., ''Aerodynamics'', Section 3.5
:q = \frac\rho\, u^2
where (in SI units):
* is the dynamic pressure in pascals ...
of the fluid flow around the airfoil, and the planform area of the airfoil.
# ''
Ballistic coefficient
In ballistics, the ballistic coefficient (BC, ''C'') of a body is a measure of its ability to overcome air resistance in flight. It is inversely proportional to the negative acceleration: a high number indicates a low negative acceleration—the ...
'' (BC) (aerodynamics) (units of kg/m
2) - A measure of a body's ability to overcome air resistance in flight. BC is a function of mass, diameter, and
drag coefficient.
# ''
Transmission coefficient
The transmission coefficient is used in physics and electrical engineering when wave propagation in a medium containing discontinuities is considered. A transmission coefficient describes the amplitude, intensity, or total power of a transmitt ...
'' (
quantum mechanics
Quantum mechanics is the fundamental physical Scientific theory, theory that describes the behavior of matter and of light; its unusual characteristics typically occur at and below the scale of atoms. Reprinted, Addison-Wesley, 1989, It is ...
) (dimensionless) - Represents the probability flux of a transmitted wave relative to that of an incident wave. It is often used to describe the probability of a particle
tunnelling through a barrier.
# ''
Damping factor
In an audio system, the damping factor is defined as the ratio of the rated impedance of the loudspeaker (usually assumed to be ) to the Output impedance, source impedance of the power amplifier. It was originally proposed in 1941. Only the magni ...
'' a.k.a. ''viscous damping coefficient'' (Physical Engineering) (units of newton-seconds per meter) - relates a damping force with the velocity of the object whose motion is being dampened.
References
Physical quantities
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