|
CGS is an acronym for centimetre-gram-second. This is a system of physical units which preceded, and has largely been replaced by, the standard SI system (SI was based on the metre-kilogram-second system of units, hence the unofficial but occasionally used name mks). The cgs system is still in use; this is largely because many electromagnetic formulas are simpler in cgs units, but also because much of the older physics literature uses these units, and in some cases because they are more convenient in a particular context. Additionally, cgs units are still widely used in astronomy. Acronyms and initialisms are abbreviations formed from the initial letter or letters of words, such as NATO and XHTML, and are pronounced in a way that is distinct from the full pronunciation of what the letters stand for. ...
In physics and metrology, units are standards for measurement of physical quantities that need clear definitions to be useful. ...
SI (disambiguation). ...
Astronomy (Greek: αστρονομία = άστρον + νόμος, literally, law of the stars) is the science involving the observation and explanation of events occurring beyond the Earth and its atmosphere. ...
Electromagnetic Units
While for most units the difference between cgs and SI is a mere power of 10, the differences in electromagnetic units are considerable; so much so that formulas for physical laws need to be changed depending on what system of units one uses. In SI, electric current is defined via the magnetic force it exerts and charge is then defined as current multiplied with time. In one variant of the cgs system, esu, or electrostatic units, charge is defined via the force it exerts on other charges, and current is then defined as charge per time. One consequence of this approach is that Coulomb's law does not contain a constant of proportionality. SI (disambiguation). ...
Electromagnetism is the physics of the electromagnetic field: a field, encompassing all of space, composed of the electric field and the magnetic field. ...
In electricity, current is the rate of flow of charges, usually through a metal wire or some other electrical conductor. ...
In physics, magnetism is a phenomenon by which materials exert an attractive or repulsive force on other materials. ...
Charge is a word with many different meanings. ...
The statcoulomb (statC) or franklin (Fr) or electrostatic unit of charge (esu) is the physical unit for electrical charge used in the cgs electrostatic system of units. ...
In physics, Coulombs law is an inverse-square law indicating the magnitude and direction of electrical force that one stationary, electrically charged substance of small volume (ideally, a point source) exerts on another. ...
This article is about proportionality, the mathematical relation. ...
Ultimately, relating electromagnetic phenomena to time, length and mass relies on the forces observed on charges. There are two fundamental laws in action: Coulomb's law, which describes the electrostatic force between charges, and Ampère's law (also known as Biot-Savart's law), which describes the electrodynamic (or electromagnetic) force between currents. Each of these includes one proportionality constant, or . The static definition of magnetic fields yields a third proportionality constant, . The first two constants are related to each other through the speed of light, (the ratio of over must equal ). In physics, Coulombs law is an inverse-square law indicating the magnitude and direction of electrical force that one stationary, electrically charged substance of small volume (ideally, a point source) exerts on another. ...
The word proportionality may have one of a number of meanings: In mathematics, proportionality is a mathematical relation between two quantities. ...
Cherenkov effect in a swimming pool nuclear reactor. ...
We then have several choices:
| | | yields | | | | electrostatic cgs system | | | | electromagnetic cgs system | | | | Gaussian cgs system | | | | SI | There are actually about half a dozen systems of electromagnetic units in use, most based on the cgs system. These include emu, or electromagnetic units (chosen such that the Biot-Savart Law has no constant of proportionality), Gaussian, and Heaviside-Lorentz units. A key virtue of the Gaussian CGS system is that electric and magnetic fields have the same units, both ε0 and μ0 are 1, and the only dimensional constant appearing in the equations is c, the speed of light. The Heaviside-Lorentz system has these desirable properties as well, but is a "rationalized" system (as is SI) in which the charges and fields are defined in such a way that there are many fewer factors of 4π appearing in the formulas, and it is in Heaviside-Lorentz units that the Maxwell equations take their simplest possible form. The Biot-Savart Law describes the magnetic field set up by a steadily flowing line current: the field produced by a current element is where is the magnetic constant I is the current, measured in amperes is the unit displacement vector from the element to the field point Hence, integrating...
Maxwells equations are the set of four equations, attributed to James Clerk Maxwell, that describe the behavior of both the electric and magnetic fields, as well as their interactions with matter. ...
Further complicating matters is the fact that some physicists and engineers use hybrid units, such as volts per centimetre for electric field. Engineering is the application of science to the needs of humanity. ...
The volt is the SI derived unit for electric potential and voltage (derived from the ampere and watt). ...
cm redirects here, alternate uses: cm (disambiguation) A centimetre (symbol cm; American spelling: centimeter) is an SI unit of length. ...
Units The units of cgs (specifically esu) are as follows: The mantissas 2998, 3336, 1113, and 8988 are derived from the speed of light and are more precisely 299792458, 333564095198152, 1112650056, and 89875517873681764. In general English usage, length (symbol: l) is but one particular instance of distance – an objects length is how long the object is – but in the physical sciences and engineering, the word length is in some contexts used synonymously with distance. Height is vertical distance; width (or breadth) is...
cm redirects here, alternate uses: cm (disambiguation) A centimetre (symbol cm; American spelling: centimeter) is an SI unit of length. ...
Mass is a property of physical objects that, roughly speaking, measures the amount of matter they contain. ...
For other meanings of gram, see gram (disambiguation). ...
8:17 am, August 6, 1945, Japanese time. ...
This article is about the unit of time. ...
In physics, a net force acting on a body causes that body to accelerate; that is, to change its velocity. ...
In physics, the dyne is a unit of force specified in the centimetre-gram-second (cgs) system of units, symbol dyn. One dyne is equal to exactly 10-5 newtons. ...
This article is about the SI unit of force. ...
...
The joule (symbol J, also called newton metre, or coulomb volt) is the SI unit of energy and work. ...
Mechanical power In physics, power (symbol: P) is the amount of work W done per unit of time t. ...
The watt (symbol: W) is the SI derived unit for power. ...
Pressure (symbol: p or P) is the measure of the force that acts on a unit area. ...
The barye (symbol: Ba)is the CGS unit of pressure. ...
The pascal (symbol Pa) is the SI unit of pressure. ...
Viscosity is a measure of the resistance of a fluid to deformation under shear stress. ...
The poise (P) is the cgs unit of viscosity, 1 P = 1 g·cm-1·s-1 The SI analog is 1 pascal second (Pa·s) = 1 kg·m-1·s-1 = 10 P. It is named after Jean Louis Marie Poiseuille. ...
The pascal second (symbol Pa·s) is the SI unit of dynamic viscosity. ...
Electric charge is a fundamental property of some subatomic particles, which determines their electromagnetic interactions. ...
The statcoulomb (statC) or franklin (Fr) or electrostatic unit of charge (esu) is the physical unit for electrical charge used in the cgs electrostatic system of units. ...
The coulomb, symbol C, is the SI unit of electric charge, and is defined in terms of the ampere: 1 coulomb is the amount of electric charge (quantity of electricity) carried by a current of 1 ampere flowing for 1 second. ...
Electrical potential is the potential energy per unit charge associated with a static (time-invariant) electric field, also called the electrostatic potential or the electric potential, typically measured in volts. ...
The statvolt is the unit of voltage and electrical potential used in the cgs system of units. ...
The volt is the SI derived unit for electric potential and voltage (derived from the ampere and watt). ...
In physics, an electric field or E-field is an effect produced by an electric charge that exerts a force on charged objects in its vicinity. ...
In physics, a magnetic field is an entity produced by moving electric charges (electric currents) that exerts a force on other moving charges. ...
The oersted is the CGS unit of magnetic induction. ...
Magnetic field density, otherwise known as magnetic flux density, is essentially what the layman knows as a magnetic field - akin to a gravitational or electric field. ...
For a biography of the mathematician, see: Carl Friedrich Gauss The gauss, abbreviated as G, is the cgs unit of magnetic flux density or magnetic induction (B), named after the German mathematician and physicist Carl Friedrich Gauss. ...
The tesla (symbol T) is the SI derived unit of magnetic flux density (or magnetic inductivity). ...
Magnetic flux, usually denoted by Greek letter Φ, is a measure of quantity of magnetism, taking account of the strength and the extent of a magnetic field. ...
The compound derived CGS unit, the maxwell, abbreviated as Mx, is the unit for the magnetic flux. ...
This article is in need of attention. ...
Electromagnetic induction is the production of an electrical potential difference (or voltage) across a conductor situated in a changing magnetic field. ...
For a biography of the mathematician, see: Carl Friedrich Gauss The gauss, abbreviated as G, is the cgs unit of magnetic flux density or magnetic induction (B), named after the German mathematician and physicist Carl Friedrich Gauss. ...
Electrical resistance is a measure of the degree to which an electrical component opposes the passage of current. ...
Electrical resistivity (also known as specific electrical resistance) is a measure indicating how strongly a material opposes the flow of electric current. ...
Capacitance is the ability of a capacitor to store potential difference or voltage for a given amount of stored charge. ...
The farad (symbol F) is the SI unit of capacitance (named after Michael Faraday). ...
Inductance is a physical characteristic of an inductor, which is an electrical device that produces at any time a voltage proportional to the instantaneous rate of change in current flowing through it. ...
The henry (symbol H) is the SI unit of inductance. ...
The significand (also coefficient or, more informally, mantissa) is the part of a floating-point number that contains its significant digits. ...
Cherenkov effect in a swimming pool nuclear reactor. ...
A centimetre of capacitance is the capacitance between a sphere of radius 1 cm in vacuum and infinity. The capacitance Cbetween two spheres of radii R and r is
- . By taking the limit as R goes to infinity we see C equals r.
See Also |
Feeds |
Contact