Go Back   Home > Forums > General Interest > Everything Else

Everything Else Anything related to audio / video / electronics etc) BUT remember- we have many new forums where your thread may now fit! .... Parts, Equipment & Tools, Construction Tips, Software Tools......

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 1st April 2011, 03:16 PM   #1
Banned
 
Join Date: Sep 2008
Default learning circuit theory

So i am mainly learning about kirchoffs law and analysing combinations of resistors and possibly other components, which cannot be analysed by ohms law alone. However i have a number of questions which hinder my understanding that id like to post and hopefully gain some answers.

We have a voltage law and a current law which states respectively that:
sum of pd around any closed loop is 0.
current into any node = current leaving that node or equivalently the current into any node is 0 where a plus or minus sign is used to denote the direction of current wrt that node.

First i will ask where these laws come from and what they really mean?
  Reply With Quote
Old 1st April 2011, 07:54 PM   #2
DF96 is offline DF96  England
diyAudio Member
 
Join Date: May 2007
Sum of pd around a loop equals zero comes from the property of electric fields generated by static charges. To be technical, the static electric field is a conservative field, which means that if you move a test charge around from A to B the energy gained/lost does not depend on the route you take. From this comes the concept of potential. If you go around a loop then when you come back to the starting position the net energy change is zero, so the voltage change is zero. Mathematically, it comes from Maxwell's equations give the static E field from a Div only. (Magnetism is different as it based on Curl, like a changing electric field).

Sum of current into a node equals zero comes from conservation of electric charge.
  Reply With Quote
Old 2nd April 2011, 02:02 AM   #3
Banned
 
Join Date: Jan 2008
Blog Entries: 2
They come from Maxwell, James Clerk.

He looked at a load of existing knowledge about electricity and magnetism and consolidated it into 4 basic equations, these otherwise known as Ampere's Circuital Law (which he elaborated), Gauss's Law, Gauss's Law for magnetism and Faraday's Law. These describe the behaviour of electric and magnetic fields and electric charge and current in space. You can look them up in Wikipedia, but the compact mathematical expressions you will find using the curl and divergence operators require practise to manipulate. They can be broken down to some simplifications and special cases such as Ohm's (or Kirchoffs) Law.

What they really mean is a great deal. They don't account for mass or gravity so they don't explain everything, but they're a fundamental description of some aspects of matter and space and they permit the understanding and prediction of the behaviour (such as the speed of light) of electromagnetic (radio) waves, which was the main impact of his work and without which Einstein's later work on relativity would have been impossible.

It's normal to work up to a consolidated understanding of the subject by studying the simplifications and developing mathematical skills from the ground up, starting with algebra and progressing through calculus and vector analysis.

w

Other than that, they come from observations.

Last edited by wakibaki; 2nd April 2011 at 02:08 AM.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
help with learning krish2487 Solid State 9 15th December 2008 06:03 PM
new learning aardvarkash10 Tubes / Valves 1 23rd November 2008 07:47 AM
Circuit Theory and Applications archive? jan.didden Everything Else 4 21st April 2008 03:17 AM
learning how to do this famine24 Tubes / Valves 1 23rd November 2004 01:47 AM
Zen circuit theory ding Pass Labs 4 22nd June 2001 03:48 AM


New To Site? Need Help?

All times are GMT. The time now is 05:15 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2