The centimetergramsecond system cgs is a system of physical units. In cgs units, the equation for magnetic force looks different. The course will use cgs units, as does our textbook classical electrodynamics, 2nd ed. The centimetergramsecond system cgs is a system of. Some are important for the interpretation of older scientific texts, but their use is not encouraged. The history of the metre and the kilogram, two of the fundamental units on which the system is based, goes back to the french revolution. In 1901 giorgi showed that it is possible to combine the mechanical units of this meterkilogramsecond. Physical quantities and units department of physics. The second number gives the conversion in the opposite direction. Apart from the mks system, there were others such as the cgs unit sys. Cgs emu system, the centimetre is the unit of inductance.
The centimetregramsecond 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. Units conversion 2 which tells you that 10 meters equals about 32. Few users of cgs esu and emu fully understand the complexity of the system. Three such systems, the cgs, the fps or british system and the mks system were in use extensively till recently. In physics, there are various terms and quantities.
Carman, numbers and units for physics wiley, new york. The international system of units is the standard modern form of the metric system. One kg is defined as the mass of a particular solid cylinder of platinumiridium alloy kept at sevres. Measurement without units of a physical quantity has no meaning. Cgs units are probably largely maintained by those who work with cgs units in a relatively narrow field and who therefore do not often have occasion to convert. The earths atmosphere at sea level has a pressure of 1. Conversion between these base units and all the derived units are quite simply given by an appropriate power of 10.
Other units that may be encountered for expressing dipole moment are cgs esu, debye, and atomic unit. It is defined by taking the fixed numerical value of the caesium frequency cs, the unperturbed groundstate hyperfine transition frequency of the caesium 3 atom, to be 9 192 631 770 when expressed in the unit hz. Units are also classified into various types such as c. The unit for magnetic field, b, is called the gauss, g, where 1 g 1 dyne esu. For volume, the liter l is actually not a derived unit since it requires a numeric multiplie r, that is, 1 l 10. But, the fourth unit depends on whether it is based on the cgs electrostatic system of units esu or based on the cgs electromagnetic system of units emu. 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. Description of units mechanical units quantity length mass time force work, energy power dynamic viscosity kinematic viscosity cgs centimeter gram second dyne erg. Each system has its own set of derived units for force, energy, electric current, etc. To convert from one system to the other, cgs unit factor mks unit. It comprises a coherent system of units of measurement starting with seven base units, which are the second the unit of time with the symbol s, metre. It is \rationalized in the sense that there are no factors 4. The abbreviations are mmetre, ggramme, nnewton,jjoule,ttesla,ggauss,aamp,oeoersted,wbweber,mxmaxwell.
The cgs system is based on three basic quantities for length, mass, and time using the centimete r, gram and second, respectivel y. In earlier time scientists of different countries were using different systems of. Reference points help build that innate understanding of how much. The magnetic field, b, must be in units of force per charge per velocity. In this case, it tells you that 1 foot is equal to about 0. The different quantities in physics can be expressed in various units. The basic units of the cgs system are cm centimeter, g gram, and s second. Mks unit cgs unit conversion mass kilogram gram 1kg 103gm.
The centimetregramsecond system of units abbreviated cgs or cgs is a variant of the. The symbol g is a unit of measurement since it is upright rather than italicized as required for a variable, and it stands for gram. Gaussian units and cgs emu are the same for magnetic properties. Electric and magnetic units the esu and emu unit systems are cgs systems. However, work out the dimensions of p and you will find that its dimensions are q l. Conversion of formulae and quantities between unit systems. In the cgs system, force and ene r gy are quantified with the derived units of dyne g cms 2 and e r g g cm 2 s 2, respectivel y.
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