On Fri, 08 Jan 2010 11:08:14 -0700, Dave wrote:

On 1/8/2010 7:28 AM Dave wrote:
The formula I found for total ohms in a series circuit is to add up all
ohms in the circuit. For parallel circuits its 1/RT = 1/R1 + 1/R2 so
1/2.8398 + 1/5.6534 = 8.5472/16.35980892 which is something like 5.2245
ohms. The total for a combo circuit is to add the parallel value to the
series values and I come up with a total of 19.9873. Nothing even close
to your 4.1433. So I'm clearly not understanding how resistance math is
supposed to work.

Ok, I screwed my math up on the parallel circuit. Here's my revised math:
1 / (1/2.8398 (0.35213) + 1/5.6534 (0.17688) = .52901) = 1.89032 ohms.

So add this to the remaining values stated:

1.89032 + 7.0134 + 7.7494 = 16.65312

Still no where near your 4.1433.

What am I doing wrong?


Not following the rules.
You need to analyze the circuit. You have a parrallel circuit composed
of one resistance on the bottom and a combination on the top. The
combination is a series circuit of a single resistance and a parralel
sub-circuit of 2 in parrallel.

You need to solve the parallel sub-string first, and add the series
component to it, then solve the resulting parallel string.