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The centimetre–gram–second system of units ( 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 ...
v. t. e. In special relativity, four-momentum (also called momentum–energy or momenergy[ 1]) is the generalization of the classical three-dimensional momentum to four-dimensional spacetime. Momentum is a vector in three dimensions; similarly four-momentum is a four-vector in spacetime. The contravariant four-momentum of a particle with ...
The mass-to-charge ratio ( m / Q) is a physical quantity relating the mass (quantity of matter) and the electric charge of a given particle, expressed in units of kilograms per coulomb (kg/C). It is most widely used in the electrodynamics of charged particles, e.g. in electron optics and ion optics .
Electron mobility is almost always specified in units of cm 2 /(V⋅s). This is different from the SI unit of mobility, m 2 /(V⋅s). They are related by 1 m 2 /(V⋅s) = 10 4 cm 2 /(V⋅s). Conductivity is proportional to the product of mobility and carrier concentration. For example, the same conductivity could come from a small number of ...
The plus sign ( +) and the minus sign ( −) are mathematical symbols used to denote positive and negative functions, respectively. In addition, + represents the operation of addition, which results in a sum, while − represents subtraction, resulting in a difference. [1] Their use has been extended to many other meanings, more or less analogous.
Negative refraction. Negative refraction is the electromagnetic phenomenon where light rays become refracted at an interface that is opposite to their more commonly observed positive refractive properties. Negative refraction can be obtained by using a metamaterial which has been designed to achieve a negative value for (electric) permittivity ...
A surface charge is an electric charge present on a two-dimensional surface. These electric charges are constrained on this 2-D surface, and surface charge density, measured in coulombs per square meter (C•m −2 ), is used to describe the charge distribution on the surface. The electric potential is continuous across a surface charge and the ...
Linear charge density (λ) is the quantity of charge per unit length, measured in coulombs per meter (C⋅m −1 ), at any point on a line charge distribution. Charge density can be either positive or negative, since electric charge can be either positive or negative. Like mass density, charge density can vary with position.