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Prentice's rule, named so after the optician Charles F. Prentice, is a formula used to determine the amount of induced prism in a lens: = where: P is the amount of prism correction (in prism dioptres) c is decentration (the distance between the pupil centre and the lens's optical centre, in millimetres)
The Scherrer equation can be written as: where: τ {\displaystyle \tau } is the mean size of the ordered (crystalline) domains, which may be smaller or equal to the grain size, which may be smaller or equal to the particle size; K {\displaystyle K} is a dimensionless shape factor, with a value close to unity.
Gibbs–Thomson equation. The Gibbs–Thomson effect, in common physics usage, refers to variations in vapor pressure or chemical potential across a curved surface or interface. The existence of a positive interfacial energy will increase the energy required to form small particles with high curvature, and these particles will exhibit an ...
Applications. There are many different effective medium approximations, each of them being more or less accurate in distinct conditions. Nevertheless, they all assume that the macroscopic system is homogeneous and, typical of all mean field theories, they fail to predict the properties of a multiphase medium close to the percolation threshold due to the absence of long-range correlations or ...
The formula for decay correcting is: = where is the original activity count at time zero, is the activity at time "t", "λ" is the decay constant, and "t" is the elapsed time.
Antoine equation. The Antoine equation is a class of semi-empirical correlations describing the relation between vapor pressure and temperature for pure substances. The Antoine equation is derived from the Clausius–Clapeyron relation. The equation was presented in 1888 by the French engineer Louis Charles Antoine [ fr] (1825–1897).
The Van 't Hoff equation relates the change in the equilibrium constant, Keq, of a chemical reaction to the change in temperature, T, given the standard enthalpy change, ΔrH⊖, for the process. The subscript means "reaction" and the superscript means "standard". It was proposed by Dutch chemist Jacobus Henricus van 't Hoff in 1884 in his book ...
The basic method is that the valence V of an atom is the sum of the individual bond valences vi surrounding the atom: The individual bond valences in turn are calculated from the observed bond lengths. Ri is the observed bond length, R0 is a tabulated [1] parameter expressing the (ideal) bond length when the element i has exactly valence 1, and ...
In this case, a correction factor in the numerator is necessary:: 248 : 123 [ α ] λ T = 100 × α l × c {\displaystyle [\alpha ]_{\lambda }^{T}={\frac {100\times \alpha }{l\times c}}} When using this equation, the concentration and the solvent may be provided in parentheses after the rotation.
A chemical equation is the symbolic representation of a chemical reaction in the form of symbols and chemical formulas.The reactant entities are given on the left-hand side and the product entities are on the right-hand side with a plus sign between the entities in both the reactants and the products, and an arrow that points towards the products to show the direction of the reaction.