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  2. RC time constant - Wikipedia

    en.wikipedia.org/wiki/RC_time_constant

    It is the time required to charge the capacitor, through the resistor, from an initial charge voltage of zero to approximately 63.2% of the value of an applied DC voltage, or to discharge the capacitor through the same resistor to approximately 36.8% of its initial charge voltage.

  3. Madelung constant - Wikipedia

    en.wikipedia.org/wiki/Madelung_constant

    The electrostatic energy of the ion at site r i then is the product of its charge with the potential acting at its site , = =. There occur as many Madelung constants M i in a crystal structure as ions occupy different lattice sites.

  4. Born–Landé equation - Wikipedia

    en.wikipedia.org/wiki/Born–Landé_equation

    The electrostatic potential energy, E pair, between a pair of ions of equal and opposite charge is: = where z = magnitude of charge on one ion e = elementary charge, 1.6022 × 10 −19 C ε 0 = permittivity of free space 4 π ε 0 = 1.112 × 10 −10 C 2 /(J·m)

  5. Mathematics of three-phase electric power - Wikipedia

    en.wikipedia.org/wiki/Mathematics_of_three-phase...

    The plotted line represents the variation of instantaneous voltage (or current) with respect to time. This cycle repeats with a frequency that depends on the power system. In electrical engineering, three-phase electric power systems have at least three conductors carrying alternating voltages that are offset in time by one-third of the period ...

  6. Kubo formula - Wikipedia

    en.wikipedia.org/wiki/Kubo_formula

    The Kubo formula, named for Ryogo Kubo who first presented the formula in 1957, [1] [2] is an equation which expresses the linear response of an observable quantity due to a time-dependent perturbation.

  7. Variational method (quantum mechanics) - Wikipedia

    en.wikipedia.org/wiki/Variational_method...

    This is minimal for Z = 27/16 implying shielding reduces the effective charge to ~1.69. Substituting this value of Z into the expression for H yields 729E 1 /128 = −77.5 eV, within 2% of the experimental value, −78.975 eV. [5] Even closer estimations of this energy have been found using more complicated trial wave functions with more ...

  8. Energy drink - Wikipedia

    en.wikipedia.org/wiki/Energy_drink

    Energy drinks have the effects caffeine and sugar provide, but there is little or no evidence that the wide variety of other ingredients have any effect. [3] Most of the effects of energy drinks on cognitive performance, such as increased attention and reaction speed, are primarily due to the presence of caffeine. [4]

  9. Larmor formula - Wikipedia

    en.wikipedia.org/wiki/Larmor_formula

    For a particle whose velocity is small relative to the speed of light (i.e., nonrelativistic), the total power that the particle radiates (when considered as a point charge) can be calculated by the Larmor formula: = (˙) = = = = where ˙ or is the proper acceleration, is the charge, and is the speed of light. [2]