# Finding voltage and phase

Discussion in 'Homework Help' started by gbox, Dec 31, 2015.

1. ### gbox Thread Starter Member

Dec 29, 2015
42
0
Find V_ab and |V_ab| and the phase of V_ab.

I thought about using Thevenin, but than I thought that the elements above AB are the same as under AB.

Or I can just say that $$V_AB=V_source-Z_R-( V_source-Z_C)$$?
How should I approach this?

Last edited: Dec 31, 2015
2. ### WBahn Moderator

Mar 31, 2012
17,716
4,788
Do you know about complex impedance?

3. ### gbox Thread Starter Member

Dec 29, 2015
42
0
I know that
Code (Text):
1. [plain]$$V_source=V_in*e^{\omega t} Z_R=R and Z_C=\frac{1}{\omega c i}$$[/plain]

4. ### gbox Thread Starter Member

Dec 29, 2015
42
0
Here is the attempt

5. ### WBahn Moderator

Mar 31, 2012
17,716
4,788
Okay, so if you were asked merely to find the voltage at Node A, could you do it?

If you were asked to merely find the voltage at Node B, could you do it?

If so, recognize that V_ab is, by definition, the voltage at Node A minus the voltage at Node B.

6. ### gbox Thread Starter Member

Dec 29, 2015
42
0
I have used voltage divider is it right?

7. ### WBahn Moderator

Mar 31, 2012
17,716
4,788
Your image capture doesn't have enough contrast for my tired old eyes to read easily, but it appears you are starting out on the right path.

8. ### anhnha Active Member

Apr 19, 2012
773
45
Your approach using voltage divider is right but you need to review the formula to calculate voltage across each element of a voltage divider.