# Homework Help: Resistance Propagation of Error

1. Oct 1, 2006

### mb85

We recently did a Resistance in Circuits lab.

My coded resistances were
33, 100 and 220.
The measured resistance was
33.3, 101.6 and 219

So we did 3 setups. (Series, Parallel and Combination)

Series = 351.8 measured ohms
Parallel = 22.5 measured ohms
Combinations = 101.5 measured ohms

The links below are scanned images of my work.
http://img.photobucket.com/albums/v600/bozym618/seriesandparallel.jpg [Broken]

http://img.photobucket.com/albums/v600/bozym618/combination.jpg [Broken]

I am confused on what i am comparing.
I find the calculated Req with the uncertainty... so I am comparing that to the measured, but i am confused on what to do with the uncertainty.
I need to find the discrepancy and say if it is signi. or insigni.

For Parallel i found, 22.5 -22.3 = 0.2 and the error was 0.141
So its Sig. But the rest confused me.

I hope someone can help me understand.

Last edited by a moderator: May 2, 2017
2. Oct 1, 2006

### mb85

anyone have any ideas?

3. Oct 2, 2006

### Mindscrape

What equations did you use? There would be a couple ways to measure resistance, and a couple ways to find the error. If you used $$R = \frac{V}{i}$$ or any number of other equations for resistance then you would be able to find the uncertainty with the master rule for uncertainty, which is $$\pd q = \sqrt{(\frac{\partial q}{\partial x}\delta x)^2 +... + (\frac{\partial q}{\partial z}\delta z)^2$$ for whatever variables you have.

You could also use standard deviations for uncertainty, which would be my suggestion.

Last edited: Oct 2, 2006