# Series-parallel Combination AC circuits Worksheet

Discussion in 'Feedback and Suggestions' started by Unregistered, May 16, 2010.

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1. ### Unregistered Thread Starter Guest

Okay I may be wrong with this, but it seems there is an error in

AC power

Question 31, part 2.

Here are my calculations for working out the line current:
1/Xc + 1/Za = 1 / Ztot
(2*60*pi*270x10^-6)<-90 + 1/(5<34) = 1/Ztot
Z tot = 1 / ((2*60*pi*270x10^-6)<-90 + 1/(5<34))
Z tot = 3.698 < 52.183

This gives a line current of V/Z = I
I = 240 / (3.698 < 52.183)
I = 64.8999 < -52.18

The supposed answer is I line = 39.87 A
It seems as if calculations went like this:

1/Xc + 1/Za = 1 / Ztot
(2*60*pi*270x10^-6)<90 + 1/(5<34) = 1/Ztot **Note 90, not -90
Z tot = 1 / ((2*60*pi*270x10^-6)<90 + 1/(5<34))
Z tot = 6.02 < 3.47

I = V / Z
I = 39.87 < - 3 .47.

As far as I'm aware a capacitor with value 10 F has
Xc = (1 / (2pi*f*10)) < -90.

Please let me know if this is infact an error in the answer, or an error on my part.

Regards,
Steve

2. ### Spoon Member

May 18, 2009
12
0
I think you are incorrectly changing the 90,
will look into it soon

3. ### beenthere Retired Moderator

Apr 20, 2004
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We really can't interact with non-members. If you wish to continue, please register with us.

Thanks for the interest.