What measurement system is used to measure electrical properties such as voltage, current, etc.? I understand the units are defined by SI (at least according to this article), but is that considered the measurement system used to measure properties of electricity?

It is confusing me because I have some people telling me that scientific notation is required for it to be considered part of the SI system, and that engineering notation is not part of the SI system.

So I am unclear if I am indeed using the SI system when measuring electrical properties. If not, then what system am I using?

To clear up ambiguity, the old definition of "the metric system" is not intended to be the topic of the question. I aim to clarify that any statements I make that refer to "the metric system" in comments refer to the modern International System of Units (SI).

  • \$\begingroup\$ SI is based on and extending the metric system. I really do not understand your other questions. \$\endgroup\$
    – Eugene Sh.
    Commented Sep 19, 2019 at 18:02
  • \$\begingroup\$ OK, I will update my question. As far as I can tell the metric system is synonymous with the International System of Units. \$\endgroup\$ Commented Sep 19, 2019 at 18:03
  • \$\begingroup\$ Your link has another link defining precisely what SI system is. Here it is if you missed. \$\endgroup\$
    – Eugene Sh.
    Commented Sep 19, 2019 at 18:05
  • \$\begingroup\$ Oh ok. So the answer would be yes then? Does the International System of Units body define how engineering notation is noted/written? \$\endgroup\$ Commented Sep 19, 2019 at 18:06
  • 1
    \$\begingroup\$ As far as I know, SI system has nothing to say about scientific/engineering notation. Engineering notation is even set so that it matches SI prefixes, so I don't see how it would be wrong to use it. \$\endgroup\$
    – TemeV
    Commented Sep 19, 2019 at 18:09

1 Answer 1


The term "metric system" is not the correct terminology. We use the SI, the International System of Units that defines certain base units as well as a much larger set of derived units. The base units must be defined in terms of reproducible physical phenomena, then the derived units are defined in terms of the base units.

The ampere is a base unit. According to IEEE/ASTM standard SI 10-2016:

The ampere is that constant current that, if maintained in two straight parallel conductors of infinite length, of negligible circular cross section, and placed one meter apart in a vacuum, would produce between these conductors a force equal to \$2\times 10^{-7}\$ newton per meter of length.

The volt, the farad, the coulomb, etc. are derived units.

The SI does not say that you can or can not use exponential notation and it does not specify what "engineering notation" would be. It tells you what letter to use for the symbol for a unit (e.g. F for farad) and specifies the prefixes that can be used instead of exponential notation. There are quite a few other rules and suggestions...too many to include here.

  • \$\begingroup\$ Except that "electricity" is not measured with the SI or anything else. There are SI units for current, voltage, charge, capacitance, inductance, power, and energy but there is no unit for "electricity". \$\endgroup\$ Commented Sep 20, 2019 at 0:30
  • \$\begingroup\$ I updated my question to avoid confusion. \$\endgroup\$ Commented Sep 20, 2019 at 0:40
  • \$\begingroup\$ The SI system is used to specify quantities of electrical properties. However, the use of exponential notation, scientific notation, and/or engineering format is unrelated to the use of the SI. \$\endgroup\$ Commented Sep 20, 2019 at 0:45
  • \$\begingroup\$ I am gratefully attempting understand what you are trying to suggest. Are you saying the measurement system used to identify properties of electricity is SI, or am I not understanding? \$\endgroup\$ Commented Sep 20, 2019 at 1:01
  • \$\begingroup\$ Yes, the measurement system used to quantify characteristics or properties of phenomena related to "electricity" is SI. \$\endgroup\$ Commented Sep 20, 2019 at 1:21

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