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Vacuum pump and bell jar for vacuum experiments, used in science education during the early 20th century, on display in the Schulhistorische Sammlung ('School Historical Museum'), Bremerhaven, Germany. A vacuum (pl.: vacuums or vacua) is space devoid of matter. The word is derived from the Latin adjective vacuus (neuter vacuum) meaning "vacant ...
A vacuum gauge is used to measure pressures lower than the ambient atmospheric pressure, which is set as the zero point, in negative values (for instance, −1 bar or −760 mmHg equals total vacuum). Most gauges measure pressure relative to atmospheric pressure as the zero point, so this form of reading is simply referred to as "gauge pressure".
Vacuum permittivity, commonly denoted ε 0 (pronounced "epsilon nought" or "epsilon zero"), is the value of the absolute dielectric permittivity of classical vacuum. It may also be referred to as the permittivity of free space , the electric constant , or the distributed capacitance of the vacuum.
The vacuum magnetic permeability (variously vacuum permeability, permeability of free space, permeability of vacuum, magnetic constant) is the magnetic permeability in a classical vacuum. It is a physical constant , conventionally written as μ 0 (pronounced "mu nought" or "mu zero").
The vacuum permittivity ε o (also called permittivity of free space or the electric constant) is the ratio D / E in free space. It also appears in the Coulomb force constant, = Its value is [6] [7]
Ultra-high vacuum (often spelled ultrahigh in American English, UHV) is the vacuum regime characterised by pressures lower than about 1 × 10 −6 pascals (1.0 × 10 −8 mbar; 7.5 × 10 −9 Torr). UHV conditions are created by pumping the gas out of a UHV chamber.
Dust and allergens don't stand a chance against the HEPA filter trap which can catch particles as small as .3 microns, while the handy hose attachment allows you to reach dust and cobwebs up high ...
Vacuum expected in the beam pipe of the Large Hadron Collider's ATLAS experiment [9] (operates at a pressure of 1 nPa to 10 nPa) [10] ~1 nPa Approximate solar wind pressure at Earth 's distance from the Sun [ 11 ] (variable) [ citation needed ]