Uncertainty in ammeter and voltmeter?

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Discussion Overview

The discussion revolves around the uncertainties associated with measurements taken using an ammeter and voltmeter, specifically focusing on how to determine the uncertainty in readings from a multimeter set to measure current and voltage. The scope includes conceptual understanding of measurement accuracy and instrument specifications.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification

Main Points Raised

  • One participant inquires about how to calculate the uncertainty for current readings in mA and voltage readings in volts from a multimeter.
  • Another participant notes that the accuracy of the measurement depends on the instrument used, clarifying that ohm meters measure resistance, not current.
  • A participant suggests that accuracy could be considered as half the smallest division of the instrument, though this may not always apply due to potential non-linear scales.
  • Another response emphasizes the distinction between accuracy, discrimination, and precision, indicating that these terms are not interchangeable.
  • One participant advises checking the specifications of the multimeter, which should provide accuracy details for each measurement scale.

Areas of Agreement / Disagreement

Participants express differing views on how to define and calculate measurement uncertainty, with no consensus reached on a specific method or interpretation of accuracy.

Contextual Notes

Limitations include potential non-linearity of the measurement scale and the need for specific instrument specifications to accurately determine uncertainty.

Who May Find This Useful

Individuals interested in measurement techniques, instrument accuracy, and those using multimeters in experimental or practical applications may find this discussion relevant.

CAH
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I set an ohm meter to record current in mA, smallest 0.01mA, I took three readings for several different resistances.. What would the uncertainty be?

And the same for the voltmeter but reading in volts, smallest 0.01V
 
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It depends on the accuracy of your instrument. By the way, ohm meters measure ohms, not amps.
 
Multimeter sorry! Isn't the accuracy half the smallest division?
 
CAH said:
Multimeter sorry! Isn't the accuracy half the smallest division?
It could be but not necessarily. The scale could be far from linear. Accuracy, Discrimination Precision are all very different things.
 
Try to find the specifications for your multimeter (possibly in the owner's manual). It should list the accuracy for each scale.
 

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