1. Jan 21, 2007

### clearmoon

Our teacher give us a EX. but I don't how to do .
The teacher ONLY give us a week time to finish it .
I realy hope that some one can help me !

(I ONLY KNOW Q1c & Q2a)

2. Jan 21, 2007

### mjsd

there is quite a lot there... If you don't even know how to do Q1a, then you really need to first learn about phasors, how to convert capacitance/inductance into reactance etc, .... by the sound of it I think you are lacking a lot of the basics, so much that I do not actually recommend tackling these problems for there are quite a lot concepts involved... should first learn the basics... either read your lecture notes...if they happens to be crap ...then may be try

Hambley, Electrical Engineering (principles and applications)
Cheng, Field and waves electromagnetics
Nilssonn & Riedel, Electrical Circuits
(see topics related to Steady-state sinusoidal analysis)

3. Jan 21, 2007

### chaoseverlasting

You should get your concepts cleared first, but here are the answers to the first question:

a. v=200sin(200pi t), This is of the form v=asin(wt) where w=200pi.
Capacitive reactance Xc=1/wcand$$Impedence=\sqrt(Xc^2+R^2)$$
b. Vmax=200
c.
d. Use ohm's law.
e. You have the equation of current varying with time and you know that current and voltage are 90 out of phase...

4. Jan 21, 2007

### tim_lou

5. Jan 21, 2007

### antonantal

6. Jan 22, 2007

### clearmoon

THANK YOU FOR YOUR HELP 1ST !

Q1
a) I find that in book is
Z^2 = R^2 + 1/(w^2 c^2)
R=46
c=20
w=200pi ???

b)Vmax=200 AS V=Vo sin(200pi t) ,where Vo=200 , right ???

c)PHASE DIFF. is 90"

d)
V = I R
Vosin(wt)= I R
I = ( Vo/R ) sin wt
I = Io sin wt

right ?

e)i)
applied voltage = 200V
ii)
voltage across the capacitor at that instant = 0 V

Last edited: Jan 22, 2007
7. Jan 22, 2007

### clearmoon

I have just go to this WEB.
It seem useful !

Q2.)a)
160Vc-60VL=100Vc
100c & 240VR
Vz^2 = 160^2 + 100^2
Vz =260 ?

b) I don't know
Can you give me some tips ?