# Homework Help: Do not understand Solution to this problem (AC Circuit Analysis)

1. Sep 25, 2014

### Xyius

1. The problem statement, all variables and given/known data
See The attached Images.

2. The attempt at a solution

The problem I am having with this is the following.

I do not know where he is getting these equations from. We haven't done anything like this in class. Although he keeps mentioning skills we learned in previous courses, which I took at another institution so it wasn't all exactly the same.

I see what looks like normalization constants from fourier analysis? (2/pi) And square roots of 2 (usually indicates RMS). But I do not know the logic behind the equation. Also, why is he using "X" to indicate resistance? Is it a reactance? I also don't know where he gets the expression for the phase "u."

Sorry I know this might seem like a silly question but if anyone can help me out I would really appreciate it!

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2. Sep 26, 2014

### rude man

X is the universal symbol of reactance: Z = R + jX. X = wL for inductor and -1/wC for capacitor. X is in Ohms.

I can't make out the text in the 1st (your work) slide.

3. Sep 26, 2014

### Staff: Mentor

It looks like this might be using design approximations used for inductive smoothing at the output of a bridge rectifier. The flattened current waveform suggests you can assume very effective smoothing. That constant current indicates why you can represent the load as a fixed voltage source: a steady current into a fixed load is just like a fixed voltage in opposition.

The topic may be discussed in your textbook, otherwise search for worked examples online.

Last edited: Sep 26, 2014
4. Sep 26, 2014

### Staff: Mentor

The handwriting is very clear and easy to read on my tablet, anyway.

5. Sep 26, 2014

### Staff: Mentor

Have you asked others in the class about these formulae? In any subject, your best resource is always other students in your class.

6. Sep 26, 2014

### rude man

So's mine. I was referring to the printed text.