Talk:Electric Circuit Analysis/Passive Sign Convention
Fixed the article
Blank boxes are elements, not resistors. I changed all references from resistor to element as it was appropriate.
The 3rd example was wrong. The (-) terminal has a higher potential and the current is emanating from it, making it a source.
Figure 1.4 is confusing. Why would you use arrows for voltage? Get rid of the the subscripts for V and I and get rid of the blue notation. Passive sign convention means positive voltage drops from + to - and positive current enters the + terminal. From that, you calculate P = I*V. If it comes out positive it's a resistor. If it comes out negative it's a source. That's it. You can flip the signs and flip the arrows all you want, but if you put it so that current enters the + terminal and calculate power, you'll get the right solution and correctly determine if it is a source or a resistor (and resistors aren't sources).
I hope none of my students found this page before today. (Jacob 12 Feb 2013)
This article has multiple issues
Precise definitions are needed, otherwise readers construe things differently than intended by the author. I have started by improving the definitions of circuit elements (not "components") and active and passive circuit elements. I'll continues in days ahead as I have time, which will be slowly. These improvements will address many of the issues discussed below. (doug iowa 7 Oct 2012)
A discussion on Passive sign convention
WHO CAN HELP ME IN USING PASSIVE SIGN CONVENTION.
I'm finding example 1.3 to be very confusing and possibly erroneous, because of the following: "Point A is More Positive Compared to point B.", which is shortly followed by "The Current is shown entering Point A but by the fact that current is -3A it means that the current is infact leaving at point A.", which would mean that the current is going from a lower potential at point B to a higher potential at point A, which, quoting the explanation of part 3, "The resistor has effectively powered the electric charge to a high potential point. Hence, the resistor, a passive component, supplies power in this case." Unfortunately, example 1.3 says that the resistor dissipates power. Additionally, if you look at example 1.2, VR = − 6Volts , IR = 3A, and the power is negative. Then, in example 1.3, VR = − 6Volts , IR = - 3A, so the only difference is that the current has a negative sign added. So, adding the negative sign would take the negative power from example 1.2 and make it positive. However, the signs on the resistor are reversed as well, which would throw in yet another negative sign, ultimately resulting in a negative power. Or, an easier way to compare it to example 1.2: since current is negative, flip the current arrow and call the current positive. Now example 1.3 is the exact same problem as example 1.2.
definition of passive component
Currently this page says "All components that Absorb or Dissipate electric power are called Passive components." Both vacuum tubes and transistors "absorb or dissipate power", so this definition seems to imply that vacuum tubes and transistors are passive components. Rechargeable batteries absorb power when they are recharging, right? Is a rechargeable battery a passive component?
This seems to contradict the Wikipedia: active filter article, which claims that "An active filter is a type of analog electronic filter, distinguished by the use of one or more active components i.e. voltage amplifiers or buffer amplifiers. Typically this will be a vacuum tube, or solid-state (transistor or operational amplifier)." That definition seems to imply vacuum tubes and transistors are active components.
What should we do to avoid confusing new learners? (I think trying to describe all the different definitions of "passive", as in the Wikipedia: passive component article, would leave new learners even more confused than before). --DavidCary 16:10, 20 April 2009 (UTC)
Capitalisation of words within sentences
Is there any special reason for capitalisation of words within a sentence in this article?
- If Voltage is Given as -6V it means that despite the given sign convention of the resistor, Point A is More Positive Compared to point B.
Shouldn't it be the following (wrt. capitalisation)?
- If voltage is given as -6V it means that despite the given sign convention of the resistor, point A is more positive compared to point B.
--Mortense 19:50, 19 September 2010 (UTC)
These two cases are the same so either they are redundant or there is an error in sign. "Thus for -V ; +I and -V ; +I cases the electrical charge will gain electric potential".
A resistor can never supply power
A resistor can never supply power. Current in a resistor must necessarily flow from its positive terminal to its negative terminal - "positive terminal" meaning the terminal at higher potential.
The Examples 1.1, 1.2 and 1.3 seem to be misleading.
This page has many issues. I'm going to start picking at them as I have time. If you doubt the accuracy of my edits, please be careful. There is a lot of bogosity out there on the web and even in college-level textbooks on this topic. The essence of what I want to do is to add necessary precision to the language of this article, otherwise all kinds of miss-interpretations (which the original authors probably did not intend) can be made by students trying to learn this material.