# incorrect formulas

#### bujak18

Joined Nov 12, 2008
49
I still need help from yesterday! What formulas would not be correct for series capacitor circuits if the capacitors were not assumed to be ideal? why?

#### hgmjr

Joined Jan 28, 2005
9,029
If this is a homework question, please let me know so that I can move it into the homework section if needed.

Also, if it is a homework question, what have you been able to determine on your own?

hgmjr

#### bujak18

Joined Nov 12, 2008
49
it is a home work question and i looked at the all the chapters and stuff that you guys told me to look at for help and i havnt found hardly any thing. first the question is What formulas would not be correct for series capacitor circuits if the capacitors were not assumed to be ideal? and why? all i have is this;

Ideal capacitors exist only in textbooks, not on real circuit boards.Ideal capacitors are purely reactive devices, containing absolutely zero resistive (power dissipative) effects.

#### SgtWookie

Joined Jul 17, 2007
22,210
Look again on this page, which was one of the links I posted when I replied to you yesterday:

Examine the formulas carefully.
Do you see any provisions for including ESR (equivalent series resistance) in the formulas?

#### bujak18

Joined Nov 12, 2008
49
yeah i think but i not sure.

#### Distort10n

Joined Dec 25, 2006
429
yeah i think but i not sure.
The answer would be no since the formulas presented deal only with ideal capacitors. In a non-ideal capacitor you would include equivalent series resistance (ESR) and equivalent series inductance (ESL), as well as leakage which is modeled as a resistance in parallel with the ideal capacitor.

#### darenw5

Joined Feb 2, 2008
45
Nonideal properties of capacitors, inductors and everything else are often not dealt with adequately in some texts, and in too much or too advanced detail in others. Perhaps this book will strike the right balance for some people - it assumes you already understand basic electronics and dircuit theory, and are looking for some real world street smarts at design. Analog Electronic Design: Principles and Practice of Creative Design
by Jonathan B. Scott (used copies avail. at amazon)