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I am trying to understand the difference between resolution and sensitivity. After searching on the internet and the youtube I found more or less the below definition, but in practice I can't understand it.

If the resolution is smallest portion of the signal that can be observed and a multemeter has 1mV resolution (at his lower scale) then if I try to measure 0.9mV the display will show 0V (ideally) and if I measure 1mV it will display 1mV. If I measure 1.9mV it will show again 1mV. Why isn't the resolution the same thing as the sensitivity?

Definition:

  • Resolution - the smallest portion of the signal that can be observed.
  • Sensitivity - the smallest change in the signal that can be detected.
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  • \$\begingroup\$ As I understand the minimun voltage that can cause the digits of the display of a multimeter to change is the sensitivity in practical and not the resolution. So why then the specs of a multimeter not refer only the sensitivity and they refer also the resolution which it something ideal and only in theory without any practical apply? Thanks for your reply. \$\endgroup\$
    – DarkKnight
    Commented Jul 16, 2023 at 12:44
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    \$\begingroup\$ Hi, 2 X. I recommend considering the idea of reading the 4th edition of an AIAG publication called Measurement Systems Analysis, aka The "MSA." It's only a few hundred pages and yet it covers all this and much more. In the meantime, I did find this which actually has some useful ideas presented, as well. (Not a direct answer. But should you want to read the MSA, it would come in handy in terms of providing examples of various ideas.) I don't know of a good self-study book, though. Wish I did. \$\endgroup\$
    – periblepsis
    Commented Jul 16, 2023 at 23:06
  • \$\begingroup\$ 2 X, Also, when you see words like "portion" you should immediately think in terms of percentage, or \$\frac{\text{d}\,y}{y}\$ (or \$\frac{\Delta\,y}{y}\$.) When you see words like "change" then this is just \$\text{d}\,y\$ or \$\text{d}\,x\$, alone. (Or \$\Delta\,y\$ or \$\Delta\,x\$.) Of course, context must be used as well. \$\endgroup\$
    – periblepsis
    Commented Jul 16, 2023 at 23:12
  • \$\begingroup\$ I found this very detailed article that helped me to understand what I am looking for. tek.com/en/blog/… \$\endgroup\$
    – DarkKnight
    Commented Apr 27 at 21:42
  • \$\begingroup\$ You might find this answer also helpful. \$\endgroup\$
    – periblepsis
    Commented Apr 27 at 21:48

1 Answer 1

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I am trying to understand what is the difference between Resolution and Sensitivity.

The sensitivity of a voltage measuring multimeter is in fact related to the input impedance of the measuring circuit and, is unrelated to measurement accuracy or resolution except, when the input impedance of the multimeter is low enough to cause a reading error when measuring a high impedance voltage source.

Wiki - Sensitivity and input impedance: -

The impedance of the meter varies depending on the basic sensitivity of the meter movement and the range which is selected. For example, a meter with a typical 20,000 Ω/V sensitivity will have an input resistance of 2 MΩ on the 100 V range (100 V × 20,000 Ω/V = 2,000,000 Ω).

and

Sensitivity should not be confused with resolution of a meter, which is defined as the lowest signal change (voltage, current, resistance and so on) that can change the observed reading.

I expect that there might be an equivalent name (to sensitivity) for a current measuring multimeter due to its non-zero input impedance.

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