## anonymous one year ago Resistor/Capacitor in Parallel/Series A wire has R1 and C1. This wire is in parallel to another wire containing only C2. Am I allowed to combine C1 and C2 into one effective capacitor, Ct = C1+C2? And also for a single wire with R1,C1,R2 in series in that order. Can I combine R1 and R2 into one effective resistor, Rt = R1+R2?

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1. IrishBoy123

it's possible to guess, but you really should draw this or post a diagram in order to avoid unfortunate misunderstandings. you might also wish to specify the current/voltage source as the road diverges somewhat at this point. but that should/would become apparent is a drawing/schematic/diagram.

2. anonymous

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3. IrishBoy123

the short answer to all of this is 'no'. truthfully i think you should go back to class and try establish what you are meant to be learning. do you know that capacitors do not have a resistance? they can have an impedance and be compared to resistors in AC. wish you well. sorry i can not be of more help.

4. anonymous

not trying to combine resistors WITH capacitors. I want to know if i can combine the resistors together even tough there is a capacitor in one branch,

5. anonymous

oh i see where youre confused.. it was my wording of the problem. sorry, i meant to say for the first problem "combine into one effective capacitor"

6. IrishBoy123

yes you can combine them in some way. in example 2 for DC, just add the resistors in example 1, for a DC source, you could definitely write out the DE's and do the calculus. there might be an easier way but not off top of my head. in either example for AC source, you can add their Impedances using phasors. $$Z_{capacitor} = \frac{1}{j \omega C}, \ Z_{resistor} = R$$, then just use normal series and parallel rules but bear in mind the complex numbers.

7. anonymous

ah ok thanks. my control systems professor INSISTS that for the first question, you can just use the parallel rule for capacitors and just put the resistor back on later. unfortunately he's pretty stubborn and finals are today...