# Voltage Division - AC cct.

Discussion in 'Homework Help' started by Ammar i, Feb 26, 2013.

1. ### Ammar i Thread Starter New Member

Feb 7, 2013
4
0
Hi,
We have this cut. :

and in the image below, I10 is calculated by using current division :

I tried to find it using voltage division but the answer is wrong :
Vx(of the upper node) = 100 * $\frac{j5}{4+j5}$ = 60.98 + j48.78 V

=> I10 = $\frac{Vx}{10 - j5}$ = 2.93 + 6.34 = 6.98 $\ 65.2$

which is wrong, WHY?

thanks

Last edited: Feb 26, 2013
2. ### WBahn Moderator

Mar 31, 2012
21,094
6,063
What's your basis for this equation?

Before you say, "It's the formula for a voltage divider," think about what a voltage divider is and where the formula for a voltage divider comes from.

3. ### panic mode Senior Member

Oct 10, 2011
1,485
391
you need to define two impedances before you can use voltage divider
Vx=Vin*Z2/(Z1+Z2)

can you tell what are Z1 and Z2?

4. ### WBahn Moderator

Mar 31, 2012
21,094
6,063
HINT: Z1 and Z2 have to be in series.