Millisiemens

Millisiemens (symbol mS) is a unit of electrical conductance in the SI system, equal to one thousandth of a siemens (1 mS = 0.001 S). Conductance is the reciprocal of resistance, G = 1/R.

Conversions between related units are straightforward: 1 S = 1000 mS = 1,000,000 μS, so 1 mS = 1000 μS. This makes millisiemens convenient for expressing small conductances that arise in electronics and biological contexts.

Common uses include electronics, electrochemistry, and physiology, where conductances of electrolytes, tissues, or membranes are measured. In practical terms, the conductance of a resistor is the reciprocal of its resistance, G = 1/R. For example, a 1 kΩ resistor has a conductance of 1 mS, while a 1 MΩ resistor has a conductance of 1 μS.

Notation and potential confusion: the prefix milli is written as m, so the unit is written mS. The symbol MS can denote megasiemens (10^6 S) in some contexts, which is a different quantity, so clarity in notation is important.

See also: Siemens, Ohm, electrical conductance.