Quantities and units
Which units are the most common used today?
Electromagnetism
EyeTap Doffing cylinder Gaussian units Electromagnetism Chinese units of measurement
EyeTap-Components Doffing_cylinder-Modern_doffers Gaussian_units-Alternative_unit_systems Electromagnetism-Quantities_and_units Chinese_units_of_measurement-Abstract
CCD Cameras (Charge-coupled device) are the most common type of digital camera used today. 
The most common arrangement today uses a tape doffer completely wrapped in fillet clothing, producing a web the width of the card, which is then split into strips using an array of endless tapes. These tapes used to be made of leather, but today are usually of synthetic material. 
The main alternative to the Gaussian unit system is SI units, historically also called the MKSA system of units for metre–kilogram–second–ampere. The Gaussian unit system is just one of several electromagnetic unit systems within CGS. Others include "electrostatic units", "electromagnetic units", and Lorentz–Heaviside units. Some other unit systems are called "natural units", a category that includes atomic units, Planck units, and others.SI units are by far the most common today. In engineering and practical areas, SI is near-universal and has been for decades, while in technical, scientific literature (such as theoretical physics and astronomy), Gaussian units were predominant until recent decades, but are now getting progressively less so. Natural units are most common in more theoretical and abstract fields of physics, particularly particle physics and string theory. 
Electromagnetic units are part of a system of electrical units based primarily upon the magnetic properties of electric currents, the fundamental SI unit being the ampere. The units are: ampere (electric current) coulomb (electric charge) farad (capacitance) henry (inductance) ohm (resistance) tesla (magnetic flux density) volt (electric potential) watt (power) weber (magnetic flux) In the electromagnetic cgs system, electric current is a fundamental quantity defined via Ampère's law and takes the permeability as a dimensionless quantity (relative permeability) whose value in a vacuum is unity. As a consequence, the square of the speed of light appears explicitly in some of the equations interrelating quantities in this system. Formulas for physical laws of electromagnetism (such as Maxwell's equations) need to be adjusted depending on what system of units one uses. This is because there is no one-to-one correspondence between electromagnetic units in SI and those in CGS, as is the case for mechanical units. Furthermore, within CGS, there are several plausible choices of electromagnetic units, leading to different unit "sub-systems", including Gaussian, "ESU", "EMU", and Heaviside–Lorentz. Among these choices, Gaussian units are the most common today, and in fact the phrase "CGS units" is often used to refer specifically to CGS-Gaussian units.
Chinese units of measurement () are the customary and traditional units of measure used in China. In the People's Republic of China, the units were re-standardised during the late 20th century to make them approximate SI (metric) units. Many of the units were formerly based on the number 16 instead of 10. In Hong Kong, the British Imperial system was used together with Hong Kong units of measurement, which were traditional Chinese weights and measures, and now traditional Chinese units and Imperial units are used alongside the metric system, which was introduced by legislation in 1976 as the official standard system of weights and measures. Taiwanese units of measurement, which appeared under the colonial influences of the Dutch and the Japanese, for the most part may have similar names but are different from the Chinese units of measurement. Taiwan is now fully metricated. The Chinese name for most SI units is based on that of the closest traditional unit. When it is necessary to emphasize which system is used, the words "market" (市 "shì") for traditional units or "common/standard" (公 "gōng") for SI units may be added in front of the name. SI is the official system of units, but traditional units are still ubiquitously used in everyday life. Note: The names "lí" (厘) and "fēn" (分) for small units are the same for length, area, and mass; however, they refer to different kinds of measurements. 