Systematic errors in the measurement of resistance As shown, the use of instrumentation “normal” seems impossible to get the two instruments are simultaneously requested by the real power and voltage magnitudes. Inevitably, therefore, that on each connection one of the two are measuring incorrectly. If you do ignore this contingency is clear that regardless of the accuracy inherent in the words of the instruments, it would be introducing an element of distortion, which we call systematic error that increases with the amount of uncertainty of the measurement process. However it is noteworthy that, in any of the two connections, the sign of systematic error is known and even its value can be quantified, making it possible to correct the result and the virtual elimination of this error.
In the short connection: The current flowing Ix unknown element is the difference between the current in the ammeter, and therefore indicated for this, and it consumes the voltmeter, ie Ix = I-Iv While the potential difference applied to the element to be measured coincides with the voltmeter. Ux = UY limb from limb by dividing the two equalities we obtain: Gx = I / U – Gv 7.1 Since the conducts Gx and Gv and unknown volume instrument. Therefore, the value obtained by dividing the readings of both instruments will correspond to the equivalent parallel mystery element and the voltmeter, which means a sum of two apparent conductance and a systematic error in excess conductance and resistance by default.
And the relative connection and for long: As can be seen in the above expressions are ratios for resistance to increase the value of the uncertainties, and that match the expression and the value of systematic errors, and consequently and As these are large or small, the accuracy will be affected although the systematic error is corrected. Therefore, it can establish a first selection criterion connection by choosing whichever of the two that at first present a lower systematic error.