Statohm

The statohm (symbol: statΩ) is the unit of electrical resistance in the electrostatic system of units which was part of the CGS system of units based upon the centimetre, gram and second.^[1]

The static units in that system are related to the corresponding electromagnetic units by a factor of the speed of light. Those units are known as absolute units, and so the counterpart of the statohm is the abohm (abΩ), and their proportions are:

1 statΩ ≘ c² abΩ ≈ 8.987552×10²⁰ abΩ where c is the speed of light in centimetres per second.

These units are not common now. The SI unit of resistance is the ohm (Ω). The statohm is nearly a trillion times larger than the ohm and is the largest unit of resistance ever used in any measurement system.^[2] The statohm as a practical unit is as unusably large as the abohm is unusably small.

1 statΩ ≘ c² × 10⁻⁹ Ω ≈ 8.987552×10¹¹ Ω^[3]^[4]

The sign ≘ denotes 'correspondence' between quantities. Equality does not apply, since the systems of quantities underlying the two systems of units are mutually incompatible.

References

^ Cesare Emiliani (1992), Planet Earth, Cambridge University Press, pp. 11–12, ISBN 9780521409490
^ H. Arthur Klein, The Science of Measurement: A Historical Survey, p. 448, Courier Corporation, 1974 ISBN 0486258394.
^ Cardarelli, François (2003), Encyclopaedia of Scientific Units, Weights and Measures, London: Springer, p. 23, ISBN 978-1-4471-1122-1
^ Ray E. Bolz (1973), CRC Handbook of Tables for Applied Engineering Science, CRC Press, p. 839, ISBN 978-0849302527