# Help on RLC Single type phase circuit and waveform of current against time

Discussion in 'Homework Help' started by DJF, Oct 13, 2009.

1. ### DJF Thread Starter New Member

Oct 13, 2009
4
0
I'm trying to solve these assignments but I've gotten to a poin where I'm just totally confused. Is there anyone here who can give me a hand with these questions

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2. ### Thav Member

Oct 13, 2009
82
0
I think you'll find some of the answers you're looking for by explaining what you do know and what you're missing. It will at least give us some basis on which to answer your questions. For instance, right now I'm going to tell you some things you might or might not already know because I have no background with what you're familiar with.

For the first set of questions it's important to know the rectangular and phasor notation because that will help you deal with these questions.

Knowing the reactances of the inductor and capacitor are key here.
$
X_C = \frac{1}{j \omega C} \\
X_L = j \omega L
$

Once you have those you can add up the impedance in each branch by simple addition. Adding and subtracting complex impedances is most easily done in rectangular form. Dividing and multiplying is most easily done in polar form. To convert...

$
Z_{\mathrm{rect}} = R + j X \\
Z_{\mathrm{polar}} = \sqrt{R^2+X^2} \angle \arctan{\frac{X}{R}}
$

To multiply or divide impedances in polar notation you divide and multiply the magnitude normally (before the $\angle$), and then add the phase angles for multiplication or subtract the denominator's angle from the numerator's in division.

Hope this helps!

3. ### DJF Thread Starter New Member

Oct 13, 2009
4
0
thanks for the help
i've already completed most of the question now