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# Instrument and Measurement question

The resistance of a resistor is to be determined by measuring the voltage drop across it when passing a given current, as shown in the figure in the attachment. The instrument indications are 2 mA and 12.0 V, the ammeter having a resistance of 10 Ω and the voltmeter a resistance of 10kΩ.

Calculate:
(a) the resistance of the resistor as indicated by the instrument readings;
(b) the correct resistance of the resistor allowing for instrument error;
(c) the percentage error of the uncorrected resistance with respect to the corrected resistance.

#### Solution Preview

(a)
Considering the ideal ammeter and voltmeter, we would calculate the resistance of the resistor as indicated by the instrument readings as R = V/I (using Ohm's law), where

R = resistance of the resistor
V = voltage drop as indicated by the voltmeter = 12.0 V
I = current as indicated by the ammeter = 2mA = 2*10^-3 A

Which gives us

R = 12.0 / 2*10^-3
= 6*10^3 ohms or 6 k ...

#### Solution Summary

The solution calculates the resistance of the resistor as indicated by the instrument readings, the correct resistance of the resistor allowing for instrument error, and the percentage error of the uncorrected resistance with respect to the corrected resistance.

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