Derivation Required!!

Sorry Sarah, we don't do homework. We certainly don't do exam questions (judging from the urgency in your request).

Well,

I am not asking for someone to do my homework

I am preparing a masters degree and i just can't remeber how to derive this law

anyway thanks for reply !!!!!!!!!!!!!!!!!!!!!!

In which speciality will you get your master?

Because if it is in something related to electricity you should really have a look at the basics. And by the way at your level even if you forget using basics you can come to the result.

Most surprised by your justification.

This is close enough you should be able to from here.

Do you know how to derive the complex impedance of a capacitor? For capacitors voltage, current and impedance follow Ohm's Law just as they do for resistors and inductors.

This should be very basic, foundational stuff for one getting her Master's degree. You should already know this material inside and out.

As for it's being a matter of some urgency...

Given sarah kandil previous question

"I need an aid to learn how to model the DC and AC motor circuits and how to connect supply to each of them" http://cr4.globalspec.com/thread/49001

I am lead to believe that either the masters degree has little practical theory on electrical machines (Not out-of-the-ordinary for a University masters degree) or this is not a purely electronics/electrical degree, hence the questions.

Perhaps Sarah could clarify, at her option?

There is truth in what you say, Jack. Some years ago myself and another engineer were developing software to accurately simulate, in real time, the operation of an ion source used in machines for the manufacture of integrated circuits (ion implanters).

In the course of developing the software, we took hundreds of measurements of current, voltage and other parameters from a real, working ion source in order to build an operational model for our simulator. Some of these measurements were of the current through and the voltage across a thoriated-tungsten rod "filament" (which served pretty much the same purpose - an electron source - as does the filament in a vacuum tube). Now, as anyone with practical electronics experience knows, the electrical resistance of metals changes with temperature. Kind of basic, or so I thought.

The engineer with whom I worked - an MsEE from Cornell University - couldn't make sense of the voltage & current measurements he'd spent most of the day taking. The current did not change linearly with voltage! Instead, a plot of the filament's conductance had an annoying bend to it and, consequently, the simulator did not accurately represent an actual, working ion source. He finally asked me about it and, when I explained, was astonished to learn that metals were not the simplistic, idealized concepts he'd read about in his college textbooks! The poor guy looked like he'd just been slapped him in the face. He was astonished, and so was I.

I was astonished to learn from him that Cornell MsEEs typically didn't know any of this stuff. If truth be told, I'm still astonished.

The basic capacitor charge and discharge formulas are simple, the full derivation less so (mainly because it is far less commonly used except for academic purposes). It gets even more complex if you need to mathematically take self discharge and capacitor memory effect into account.

The basics

http://en.wikipedia.org/wiki/Capacitor

http://www.electronics-tutorials.ws/rc/rc_1.html

Unfortunately as this is (technically) a homework question I cannot give you the answer (that and I don't have it handy), but for a derivation try a google search of "capacitor voltage formula derivation" or similar. You may need to search for other academic papers mentioning capacitors in some form to find what you need due to the answers rarity. Freely downloadable detailed electronic theory books may have the derivation in also.

What's your paper on?

well people,thanks for support

and much more thanks for making nice fun of me :)

I didn't make fun of you. I gave you about 85% of the answer.

As For TV P45

A special thanks you really aided

Sorry if i generalized my previous reply for all :)