Vacuum, permittivity

In this expression, e is the fundamental charge (the absolute value of the charge of an electron), Z and z2 are the charge numbers of the two ions, r12 is the distance between the centers of the ions, and E0 is the vacuum permittivity (see inside the back cover for the value of this fundamental constant). 

Vacuum magnetic permeability 245 Vacuum permittivity 31 Variable field NMR relaxometry 406 Volclay 306, 308-9... 

When the same procedure takes place in a medium such as liquid water, the vacuum permittivity in equation (1.2) is replaced by the permittivity of the medium. Normally the permittivities for a variety of solvents are expressed as relative permittivities, r, at given temperatures. Some typical values of relative permittivites are given in Table 1.4. 

Solution The discrepancy between the equation given here and Equation (27) arises from the fact that the equation above is written for cgs units whereas Equation (27) applies to SI. Remember that e = e o in Equation (27) and that the vacuum permittivity Cq usually appears with the factor 4r. When we combine Equations (6) and (26), the ratio 47r/67r reduces to 2/3. Many electrokinetic formulas differ by a factor 4ir, depending on the system of units being used, and the reader is cautioned to be aware of this difference. The presence or absence of the vacuum permittivity in the equation is the key to the system being used, although this factor is sometimes hidden, as in the case of Equation (27). 

In this relationship e and q are respectively the elementary charge and vacuum permittivity, Xj electronegativities, r. chemical hardnesses and q partial charges, whose sum should give the global electric charge z carried by the compound. The... 

Table 2.6 See Equation (2.211). e0 is the vacuum permittivity, e the relative permittivity of the medium, Vm the molar volume. E, B and V are the strengths of the electric, magnetic induction, and electric field gradient fields, respectively...

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