RESISTANCE AND CAPACITANCE IN SERIES 



therefore the phase shift is tan~^ IjcoCR. Similarly, for the low-pass filter, 

 we had 



• • 



J J 



Fout <^C (dCR 



'"^ R--^ 1+ •^' 



rationalizing 



coC a>CR 



Kout ojCR 



,^^coCr) (d^C^R^ ^[ojCrJ 



therefore the phase shift is 



1 



coCR 

 tan-i — — I — ^ tan-i —coCR 



iJOR^ {Graph 10) 



Loaded R-C high-pass filter 



If a load be connected to a simple resistance-capacitance high-pass filter 

 {Figure 3.26) we have a new effective resistance-capacitance product R'C, 



c 



Figure 3.26 



where R' = Rj^R/iR^^ -f R). Thus, the effect on the transmission character- 

 istic of the connection of the load is to move the curve bodily to the right, to a 

 new turn-over frequency, higher than the old one by the factor 



R + Rl 

 Rl 



Loaded R-C low-pass filter 



If a load be connected to a simple low-pass filter {Figure 3.27), applying 



R 

 AAW- 



c 



1 \ 



_L__r 



Figure 3.27 



Thevenin's theorem at the capacitance terminals, 

 the open-circuit e.m.f. is Kini?i/(i? + Rj), 

 the resistance looking in at the capacitance terminals is RRJ{R + Rj) 



