Filter

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Filter, filtering or filters may refer to:

Science and technology[edit]

Device[edit]

  • Filter (chemistry), a device which separates solids from fluids (liquids or gases) by adding a medium through which only the fluid can pass
    • Filter (aquarium), critical components of both freshwater and marine aquaria
    • Filter paper, a semi-permeable paper barrier placed perpendicular to a liquid or air flow. It is used to separate fine solids from liquids or air
    • Air filter, a device composed of fibrous materials which removes solid particulates such as dust, pollen, mold, and bacteria from the air
    • Oil filter, a filter to remove contaminants from engine oil, transmission oil, lubricating oil, or hydraulic oil
    • Pneumatic filter, a device which removes contaminants from a compressed air stream
    • Water filter, removes impurities from water by means of a fine physical barrier, a chemical process or a biological process
    • Cigarette filter, a part of a cigarette intended to filter the smoke inhaled by a smoker
    • Fuel filter, found in most internal combustion engines
    • Filtration (wine)
  • Sieve or macroscopic filter, a device for separating wanted elements from unwanted material

Optics[edit]

  • Optical filter, selectively transmits light of different wavelengths
    • Interference filter, reflects one or more spectral bands or lines and transmits others, while maintaining a nearly zero coefficient of absorption for all wavelengths of interest
    • Dichroic filter, a very accurate color filter used to selectively pass light of a small range of colors while reflecting other colors
    • Hydrogen-alpha filter, an optical filter that transmits a narrow bandwidth of light centred on the H-alpha wavelength
    • Photographic filter, a camera accessory consisting of an optical filter that can be inserted in the optical path
    • Infrared cut-off filter, designed to reflect or block mid-infrared wavelengths while passing visible light
    • Chelsea filter, a dichromatic optical filter used for identifying coloured stones
    • Astronomical filter, a telescope accessory used to enhance the details of celestial objects

Signal processing[edit]

Computing[edit]

Mathematics[edit]

Arts and entertainment[edit]

Other uses[edit]

  • Category-based filtering of perception, according to (objectivist interpretations of), Kant; See Category
    • Affective filter, an impediment to learning or acquisition caused by negative emotional ("affective") responses to one's environment
  • Lane splitting, a practice that cyclists use to pass slow or stopped congested traffic

See also[edit]