Hello
I'm working as a helper in small electrical firm. Today we had a debate in the work about the following chart:
you have first resistor which has 4 ohm ... than followed two resistors with 6 ohm each (these both resistors are parallel between each other). What is resistance at the end of the chart?
We debate more than an hour at the work. The answer in the book is 5 ohm. However some electrician say that correct answer is 7 ohm. What is correcy answer?
Thanks

Mike;
you can probably plug in your figures here..
http://www.sciencejoywagon.com/physicszone/lesson/07electr/kirchoff/index.html

If two 6 ohm resistors are in parallel, the resistance is 3 ohms. Add the 4 ohms in series with this and you have your 7 ohms.

********1***1
RT= R1 + ( - + - )
********R2***R3





[This message has been edited by sparky (edited 06-25-2001).]

Quick answers:

If DC, the total resistance is 7 ohms.

If AC, and one element is in reality some type of Reactance, then total Impedance is 5 ohms.

If AC, and all elements are pure resistance [true power only - no Reactance, or very minimal Reactance], then 7 ohms is the total resistance.

Scott SET

You can't believe everything you read. Every time that I teach an electrical course, I work all the problems & see if my answers agree with the teachers answer guide. It is awful embarassing to be in front of a class trying to tell them they are all wrong when they are, in fact, 100% right.

Tom

This seems to be a simple combination circuit. In my humble opinion the answer is 7 ohms.

HMEL #688

I am assuming that they were talking DC, however if the reactance is unknown how do you come up with a 5 ohm impedance and if there is a reactance there should be a corresponding phase angle. ???Or the impedance of a two terminal device is defined as follows; Voltage across the element(v(t))/ current through the element i
(t), when v(t) and i(t)have the sink reference relation and when v(t) and I(t)each vary as eEXPst.