Phase Shifter

p75213

1. The problem statement, all variables and given/known data

Can somebody explain why the voltage across the capacitor (v0) lags vi?


2. Relevant equations



3. The attempt at a solution
1. The problem statement, all variables and given/known data



2. Relevant equations



3. The attempt at a solution

Attached Thumbnails

 

p75213

I proved it with a vector diagram.
Let I be the reference phase ie. 0 degrees. Because the voltage across R is in phase with I it also has 0 phase.
The capacitor voltage V0 lags I by 90 degrees ie. -90
Vi=V0+Rvoltage.
This shows Vi vector after I (R voltage) but before V0.
Therefore Vi leads V0.

I still would appreciate a more intuitive explanation if somebody has one.

rude man

My old ARRL handbook explained this in a non-calculus way. I never bothered to try to understand it. It was obvious to me once I had diff eq's and transform techniques - meanwhile, I believe yours is the best intuitive explanation there is.