# Ac voltage across capacitor

1. May 15, 2014

### delsoo

1. The problem statement, all variables and given/known data
a resistor of 1000 ohm is connected in series to a capacitor and ac supply of frquency 50hz, if the phase diffennce of voltage supplied and current of circuirt is 30 degree, what's the capacitance of capacitor? the V max and I max in not given , how to do this ? help please!

2. Relevant equations

3. The attempt at a solution

2. May 15, 2014

### SammyS

Staff Emeritus
You need to make an attempt.

At least indicate what you know regarding such a situation, and what you've tried.

3. May 15, 2014

### delsoo

since the reacatance(X c ) =V max/ I max . i let r = 1000 ohm = resistance, Xc also = //2pI (f)(C) , so i got 1000=1/2pi (50) (c) , but i dont know where to sub the 30 degree..

4. May 16, 2014

### SammyS

Staff Emeritus
How is the instantaneous current passing through the resistor related to the instantaneous current coming into and out of the capacitor?

How is the instantaneous voltage across the resistor related to the instantaneous voltage across the capacitor?