. Hawkins electrical guide. Questions, answers & illustrations; a progressive course of study for engineers, electricians, students and those desiring to acquire a working knowledge of electricity and its applications; a practical treatise. v X —) -5- C = -^- (5) 4/ 4;c 2 But, Iav = Imax X -, and substituting this value of Iav in equation (5) gives I y - T Amax S\ t *au /-,» condenser pressure = = (6) 4 / C 2 t/ C This last equation (6) represents the condenser pressure dueto capacity at the point of maximum value, which pressure isopposed to the impressed pressure, that is, it is the maximumr
. Hawkins electrical guide. Questions, answers & illustrations; a progressive course of study for engineers, electricians, students and those desiring to acquire a working knowledge of electricity and its applications; a practical treatise. v X —) -5- C = -^- (5) 4/ 4;c 2 But, Iav = Imax X -, and substituting this value of Iav in equation (5) gives I y - T Amax S\ t *au /-,» condenser pressure = = (6) 4 / C 2 t/ C This last equation (6) represents the condenser pressure dueto capacity at the point of maximum value, which pressure isopposed to the impressed pressure, that is, it is the maximumreverse pressure due to capa Now, since by Ohms law and as E1 = -. orE = IXRK 2tt/C ^ 2-/C it follows that is the ohmic value of capacity, that — — j \~> --xpresses the resistance equivalent of capacity; using thesymbol Xc canaci mce 2x/G Xc=^ (7) ALTERNATING CURRENTS 1,049 EXAMPLE.—What is the resistance eauivalent of a 50 microfaradcondenser to an alternating current having ? frequency of 100?Substituting the given values in the expression for ohmic value Xc = 1 1 1 2a-/C 2 x X 100 X .000050 .031416 ;= ohms. If the pressure of the supply be, say 100 volts, the current wouldbe 100 = Fig. 1,288.—-Pressure and current curves, illustrating lag. The effect of inductance in a circuitis to retard the current cycle, that is to say, if the current and pressure be in phase, theintroduction of inductance will cause a phase difference, the current wave laggingbehind the pressure wave as shown. In other words, inductance causes the current wave,indicated in the diagram by the solid curve, tolag behind the pressure wave, indicated bythe dotted curve. Following the curves starting from the left end of the horizontal be noted that the current starts after the pressure starts and reverses after the pressurereverses; that is, the current lags in phase behind the Pressure, although the frequency ofboth is the same. Lag and Lead.
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