How Do I Interpret Multimeter Units Correctly?

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Discussion Overview

The discussion revolves around interpreting the units displayed on a multimeter, specifically regarding measurements of AC and DC current. Participants explore the implications of different settings on the multimeter and the accuracy of the readings obtained.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Experimental/applied

Main Points Raised

  • One participant questions whether a reading of "2.95" on a multimeter set to 20m/10A indicates 2.95 milliamperes, given the model's specifications.
  • Another participant expresses frustration with autoranging and suggests testing the multimeter with a known resistor to verify readings.
  • A different participant calculates expected current using Ohm's law but receives a reading of 2.71, leading to uncertainty about the accuracy of the multimeter's output.
  • One participant notes that the impedance of the meter may affect the current reading and suggests testing with a different resistor to confirm results.
  • Some participants assert that readings labeled with 'm' are in milliamps, while others express skepticism about the validity of the readings, particularly for AC current.
  • One participant mentions reviewing the multimeter's manual but finds it unhelpful in clarifying the unit interpretation.
  • Another participant concludes that a reading of 2.95 should be interpreted as 0.00295 Amps, despite earlier doubts about the meter's ability to measure AC current accurately.

Areas of Agreement / Disagreement

Participants express differing views on the reliability of the multimeter readings, particularly regarding AC current measurements. There is no consensus on the interpretation of the readings or the validity of the multimeter's output.

Contextual Notes

There are unresolved assumptions regarding the multimeter's specifications and the impact of impedance on current readings. Participants rely on different models and settings, leading to potential discrepancies in interpretation.

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I am trying to make sure that the data I read off my multimeter has the right units.

I have a multimeter that is a similar model to this one:
http://www.tequipment.net/BK2703B.html
You can enlarge the image to see the settings.

When I measure AC current, my result says "2.95" when the setting is on 20m/10A, using the mA and COM ports (this model doesn't seem to have AC current, but the DC current has the same label). Is it 2.95 milliamperes?

Thanks.
 
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I hate autoranging.

Put a known resistor on battery (know current) and see what the meter says.
 
This is odd. I'm just using V = I*R, with .235 V, 38.3 ohms, and it should be .00671 amps. I put the meter on 20m/10A, and it spit out 2.71. That's still in the milliamp range, but I'm just not sure if I want to trust it. I'd hate to have done all the work getting these results, just to use the wrong units.

Does anyone know for sure how to interpret the results? I hope AC doesn't have any affect on it.
 
It looks like the impendance of your meter is comparable with 38 ohms, when in 20mA mode. That would reduce the current you actually get.

Try a 9V battery with a 1k or 10k ohm resistor and see what you get.

EDIT: I just realized something. 2.71 A is way over the range of a 20mA range setting. So it must be 2.71 mA ... but checking things out by doing a measurement like you are doing is definitely a good thing, it helps you learn about and become more familiar with your meter.
 
Last edited:
2.95 should be mA, but I would think that since the meter doesn't measure AC current, it is just a bogus reading.
 
The one I linked to isn't the model I have - mine does measure AC (it has a switch for Ac/DC).

After some more testing it seems that any of the settings that are labeled with an 'm' like 20m or 200m are measured in milliamps. Thanks for your help.
 
I'd recommend having a read-over of the manual for your particular multimeter:
http://www.bkprecision.com/

(That's assuming it's actually manufactured by BK Precision)
 
I've looked over the manual - no help in there. I think I'm safe to assume it was .00295 Amps.
 
russ_watters said:
2.95 should be mA, but I would think that since the meter doesn't measure AC current, it is just a bogus reading.

this
 

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