###### Answer: SI units

The centimetre–gram–second system of units (abbreviated CGS or cgs) is a variant of the metric system based on the centimetre as the unit of length the gram as the unit of mass and the second as the unit of time. All CGS mechanical units are unambiguously derived from these three base units but there are several different ways in which the CGS system was extended to cover electromagnetism. Th…

The centimetre–gram–second system of units (abbreviated CGS or cgs) is a variant of the metric system based on the centimetre as the unit of length the gram as the unit of mass and the second as the unit of time. All CGS mechanical units are unambiguously derived from these three base units but there are several different ways in which the CGS system was extended to cover electromagnetism. The CGS system has been largely supplanted by the MKS system based on the metre kilogram and second which was in turn extended and replaced by the International System of Units (SI). In many fields of science and engineering SI is the only system of units in use but there remain certain subfields where CGS is prevalent. In measurements of purely mechanical systems (involving units of length mass force energy pressure and so on) the differences between CGS and SI are straightforward and rather trivial; the unit-conversion factors are all powers of 10 as 100 cm = 1 m and 1000 g = 1 kg. For example the CGS unit of force is the dyne which is defined as 1 g⋅cm/s so the SI unit of force the newton (1 kg⋅m/s ) is equal to 100000 dynes. On the other hand in measurements of electromagnetic phenomena (involving units of charge electric and magnetic fields voltage and so on) converting between CGS and SI is more subtle. Formulas for physical laws of electromagnetism (such as Maxwell’s equations) take a form that depends on which system of units is being used. This is because the electromagnetic quantities are defined differently in SI and in CGS whereas mechanical quantities are defined identically. Furthermore within CGS there are several plausible ways to define electromagnetic quantities leading to different “sub-systems” including Gaussian units “ESU” “EMU” and Lorentz–Heaviside units. Among these choices Gaussian units are the most common today and “CGS units” often used specifically refers to CGS-Gaussian units. Read more on Wikipedia

The CGS system goes back to a proposal in 1832 by the German mathematician Carl Friedrich Gauss to base a system of absolute units on the three fundamental units of length mass and time. Gauss chose the units of millimetre milligram and second. In 1873 a committee of the British Association for the Advancement of Science including physicists James Clerk Maxwell and

The CGS system goes back to a proposal in 1832 by the German mathematician Carl Friedrich Gauss to base a system of absolute units on the three fundamental units of length mass and time. Gauss chose the units of millimetre milligram and second. In 1873 a committee of the British Association for the Advancement of Science including physicists James Clerk Maxwell and William Thomson recommended the general adoption of centimetre gram and second as fundamental units and to express all derived electromagnetic units in these fundamental u…