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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.
Photosensitive epilepsy. Photosensitive epilepsy (PSE) is a form of epilepsy in which seizures are triggered by visual stimuli that form patterns in time or space, such as flashing lights, bold, regular patterns, or regular moving patterns. PSE affects approximately one in 4,000 people (5% of those with epilepsy). [1]
Power-line flicker is a visible change in brightness of a lamp due to rapid fluctuations in the voltage of the power supply. The voltage drop is generated over the source impedance of the grid by the changing load current of an equipment or facility. These fluctuations in time generate flicker. The effects can range from disturbance to ...
Fluorescent lamps with magnetic ballasts flicker at a normally unnoticeable frequency of 100 or 120 Hz and this flickering can cause problems for some individuals with light sensitivity; [69] they are listed as problematic for some individuals with autism, epilepsy, [70] lupus, [71] chronic fatigue syndrome, Lyme disease, [72] and vertigo. [73]
Flicker vertigo. Flicker vertigo, sometimes called the Bucha effect, is "an imbalance in brain-cell activity caused by exposure to low-frequency flickering (or flashing) of a relatively bright light." [1] It is a disorientation -, vertigo -, and nausea -inducing effect of a strobe light flashing at 1 Hz to 20 Hz, approximately the frequency of ...
Studies have shown that fluorescent lighting (which flickers 100 times a second) is twice as likely to cause headaches in office workers as non-flickering lights. [ 7 ] No similar studies have been conducted into the effect of LED (light-emitting diode) lights on sufferers of photophobia but, because LED flickering is "even more pronounced", it ...
Impressions of several natural phenomena and the principles of some optical toys have been attributed to persistence of vision. In 1768, Patrick D'Arcy recognised the effect in "the luminous ring that we see by turning a torch quickly, the fire wheels in the fireworks, the flattened spindle shape we see in a vibrating cord, the continuous circle we see in a cogwheel that turns with speed". [8]
In folklore, a will-o'-the-wisp, will-o'-wisp, or ignis fatuus (Latin for 'foolish flame'; [1] pl. ignes fatui), is an atmospheric ghost light seen by travellers at night, especially over bogs, swamps or marshes. The phenomenon is known in the United Kingdom by a variety of names, including jack-o'-lantern, [3] friar's lantern, [5][6] and ...