Voltage drop?

Adjuster

Joined Dec 26, 2010
2,148
N.B. "...we generally accept this...": if ground potential is not accessible, then it may be more convenient to use some other reference, such as a vehicle frame, equipment chassis, or common voltage line.

I also understand that on landing we may be very concerned about the electric potential on an aircraft with respect to the ground.
 

Adjuster

Joined Dec 26, 2010
2,148
And this leads to the next step... What would you observe if you removed the GROUND connection but connected the two black leads?


Perhaps this has already been done to death, with no replies yet, but let's go just a bit further.

Nowadays the instruments would probably be digital multimeters. Supposing two identical (clue) DMMs were used, a certain result would be expected. If the meters could be set to different ranges, this might or might not make a big difference - why?

If two old-fashioned analogue meters were used, what might the operator expect to have to do with one of them to get a useful reading? In this case, an interesting effect probably would be seen on setting the meters to different ranges - what is it?

Finally, if a good digital instrument and a very low-cost analogue meter were used, the student might think that the poor old analogue meter had failed. Why may this be wrong?
 

MrChips

Joined Oct 2, 2009
30,621
And this leads to the next step... What would you observe if you removed the GROUND connection but connected the two black leads?


To be quite honest, I did not know what to expect.
So I tried it in the ways you suggested, with two DVMs, different range settings, then with an analog meter and a DVM.

The results are interesting indeed.
 
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