- #1
JulienB
- 408
- 12
Homework Statement
Hi everybody! I just ran an experiment testing the accuracy of the Wheatstone bridge, which indeed yielded very small error intervals. However, we then ran a test of reproducibility and found that the deviation between the results was very high! Any idea how that could be corrected? (it's for the discussion about the uncertainty of the experiment).
Homework Equations
I've attached a picture of the experiment setup. ##R_x## is the resistor we measure, ##R_N## is the variable resistor, ##P## is the potentiometer (with wire of length ##l=100##cm with a positional sensor ##B##) and ##I## indicates where we measured the voltage (which we set to zero by moving the positional sensor). Here are the values we got for one resistor when changing ##R_N## dramatically:
##R_N = 10 \Omega \implies R_x = (12.27 \pm 0.06) \Omega##
##R_N = 1 \Omega \implies R_x = (14.9 \pm 0.4) \Omega##
##R_N = 400 \Omega \implies R_x = (8.6 \pm 0.4) \Omega##
The Attempt at a Solution
The first value (also the most accurate) is the closest to the value of the resistor (it's ##12 \Omega## according to the manufacturer). When using a value for ##R_N## close to the real ##R_x##, the positional sensor of the potentiometer is more or less in the middle (##50##cm). When ##R_N=1 \Omega##, ##B## is at ##93.7##cm; When ##R_N=400 \Omega##, ##B## is at ##2.1##cm; we took those measurements purposefully on the edges of the wire of the potentiometer.
As you can see, the deviation between the values is huge. I assumed this came from the inhomogeneity of the wire of the potentiometer, but I am not sure. Can anyone suggest me ideas on how to improve this experiment?
Thank you in advance for your answers.Julien.