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Gas lighting. Gas lighting in the historical center of Wrocław, Poland, is manually turned off and on daily. Gas lighting is the production of artificial light from combustion of a fuel gas such as methane, propane, butane, acetylene, ethylene, hydrogen, carbon monoxide, coal gas (town gas) or natural gas. The light is produced either directly ...
In its original form, a Dreamachine is a work of light art made from a cylinder with regularly spaced shapes cut out of its sides. The cylinder is then placed on a record turntable and rotated, depending on the scale, at either 78 or 45 revolutions per minute. A light bulb is suspended in the center of the cylinder with the rotation speed ...
Photopsia is the presence of perceived flashes of light in the field of vision. It is most commonly associated with: [4] Vitreous shrinkage or liquefaction, which is the most common cause of photopsia, causes a pull in vitreoretinal attachments, irritating the retina and causing it to discharge electrical impulses.
The flicker fusion threshold, also known as critical flicker frequency or flicker fusion rate, is the frequency at which a flickering light appears steady to the average human observer. It is a concept studied in vision science, more specifically in the psychophysics of visual perception. A traditional term for "flicker fusion" is "persistence ...
Some describe seeing one or more shimmering arcs of white or colored flashing lights. An arc of light may gradually enlarge, become more obvious, and may take the form of a definite zigzag pattern, sometimes called a fortification spectrum (i.e. teichopsia , from Greek τεῖχος, town wall), because of its resemblance to the fortifications ...
Gas lamps gradually started replacing oil street lamps in the United States, beginning in the first quarter of the 19th century. [3] The first street in the world to be illuminated by gaslight was Pall Mall in London, starting in 1807. [1][5] The first US city to use gas street lights was Baltimore, starting in 1817. [4]
Fluorescent lamps with magnetic ballasts flicker at a normally unnoticeable frequency of 100 or 120 Hz (twice of the utility frequency; the lamp is lit on both the positive and negative half-wave of a cycle). This flickering can cause problems for some individuals with light sensitivity [1] and are associated with headaches and eyestrain.
Stroboscopic effect is one of the particular temporal light artefacts. In common lighting applications, the stroboscopic effect is an unwanted effect which may become visible if a person is looking at a moving or rotating object which is illuminated by a time-modulated light source. The temporal light modulation may come from fluctuations of ...