Capacitance
Historical document, translated for reference. It reflects medical knowledge of the 1920s–30s and is not medical advice.
Summary
This article defines capacitance in electrostatics as the charge required to raise a body's potential to unity, assuming surrounding bodies are grounded. It explains the relationship between a sphere's radius and its capacitance, noting that the absolute unit of capacitance is the centimeter, while the practical unit is the farad.
Encyclopedia article (1928–1936)
CAPACITANCE (in electrostatics), the charge that must be imparted to a body to bring its potential to a value equal to unity, with all surrounding bodies assumed to be connected to the ground. A sphere of radius R, located in infinite space and having a charge M, acts on external points as if its mass were concentrated at the center. The potential of mass M at distance R, equal to the potential of the sphere V, is given by the formula V = M/R or M = V·R. From this, it is evident that the capacitance of a sphere is expressed by the length of the radius R in centimeters.
To bring the potential of the sphere to unity, one must impart to it as many electrostatic C.G.S. units of charge as there are centimeters in its radius. Capacitance in general is a quantity expressed in units of length, and the absolute unit of capacitance is the centimeter. The practical unit of capacitance is called the farad and is equal to 9·1011 electrostatic C.G.S. units. In practice, a capacitance one million times smaller is also used, i.e., 9·1011·10-6 = 9·105, called a microfarad.
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“Capacitance.” Soviet Medical Encyclopedia. English translation of Bolshaya Meditsinskaya Entsiklopediya, 1st ed. (Moscow, 1928–1936), ed. N. A. Semashko. https://sovietmedicalencyclopedia.com/article/capacitance/