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The formulas whhich follow may be used
to closely approximate the growth and decay of current and voltage in circuits involving L, C and R where i = instantaneous current in amperes at any given time (t), E = potential in volts as designated, R = circuit resistance in ohms, C = capacitance in farads, L = inductance in henrys, V = steady state potential in volts, V_{C} = reactive volts across C, V_{L} = reactive volts across L, V_{R} = voltage across R, |
RC = time constant of
RC circuit in seconds,
^{L}/_{R} = time constant of RL circuit in seconds, t = any given time in seconds after switch is thrown, e = a constant, 2.718 (base of the natural system of logarithms), Sw = switch The time constant is defined as the time in seconds for current or voltage to fall to ^{1}/_{e} or 36.8% of its initial value or to rise to (1 - ^{1}/_{e}) or approximately 63.2% of its final value. |
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Charging a de-energized Capacitive Circuit | Discharging an Energized Capacitive Circuit | |||
E = applied potential. |
E = potential to which
C is charged prior to closing Sw. |
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