Editing Fluorescent lamp (section)

===Flicker ===
Fluorescent lamps with magnetic [[Electrical ballast|ballasts]] flicker at a normally unnoticeable frequency of 100 or 120&nbsp;Hz and this flickering can cause problems for some individuals with [[light sensitivity]];<ref>{{cite web|url=http://www.jan.wvu.edu/soar/vision/light.html|title=Working with Light Sensitivity|access-date=2007-12-28 |archive-date=2008-03-30 |archive-url=https://web.archive.org/web/20080330090508/http://www.jan.wvu.edu/soar/vision/light.html|url-status=live}}</ref> they are listed as problematic for some individuals with [[autism]], [[epilepsy]],<ref>{{cite web|url=http://www.jan.wvu.edu/media/epilepsy.html|title=Accommodation Ideas for Employees with Epilepsy|access-date=2007-12-28 |archive-date=2008-07-25 |archive-url=https://web.archive.org/web/20080725033536/http://www.jan.wvu.edu/media/Epilepsy.html|url-status=live}}</ref> [[Systemic lupus erythematosus|lupus]],<ref>{{cite web|url=http://www.jan.wvu.edu/media/Lupus.html|title=Accommodation and Compliance Series: Employees with Lupus|access-date=2007-12-28 |archive-date=2008-05-09 |archive-url=https://web.archive.org/web/20080509073743/http://www.jan.wvu.edu/media/lupus.html|url-status=live}}</ref> [[chronic fatigue syndrome]], [[Lyme disease]],<ref>{{cite journal|pmid=10610642|title=Musculoskeletal and neurologic outcomes in patients with previously treated Lyme disease | volume=131 | issue=12|date=December 1999|journal=Ann. Intern. Med.|pages=919–26|vauthors=Shadick NA, Phillips CB, Sangha O |display-authors=etal|doi=10.7326/0003-4819-131-12-199912210-00003|s2cid=20746489 }}</ref> and [[Vertigo (medical)|vertigo]].<ref>{{cite web|url=http://www.jan.wvu.edu/enews/2004/Enews_V2-I1.htm#four |title=Accommodating People with Vertigo |url-status=dead |archive-url=https://web.archive.org/web/20080608034400/http://www.jan.wvu.edu/enews/2004/Enews_V2-I1.htm |archive-date=June 8, 2008 }}</ref> 
[[File:Fluorescentfixturebelow20806.JPG|thumb|The "beat effect" problem created when shooting photos under standard fluorescent lighting]]

A [[stroboscopic effect]] can be noticed, where something spinning at just the right speed may appear stationary if illuminated solely by a single fluorescent lamp. This effect is eliminated by paired lamps operating on a lead-lag ballast. Unlike a true strobe lamp, the light level drops in appreciable time and so substantial "blurring" of the moving part would be evident.

Fluorescent lamps may produce flicker at the power supply frequency (50 or 60&nbsp;Hz), which is noticeable by more people. This happens if a damaged or failed cathode results in slight [[Rectifier|rectification]] and uneven light output in positive and negative going AC cycles. Power frequency flicker can be emitted from the ends of the tubes, if each tube electrode produces a slightly different light output pattern on each half-cycle. Flicker at power frequency is more noticeable in the [[peripheral vision]] than it is when viewed directly.

Near the end of life, fluorescent lamps can start flickering at a frequency lower than the power frequency. This is due to instability in the negative resistance of arc discharge,<ref>{{Cite journal |first1=Stanislav |last1=Glozman |first2=Shmuel |last2=Ben-Yaakov |title=Dynamic Interaction Analysis of HF Ballasts and Fluorescent Lamps Based on Envelope Simulation |date= September–October 2001 |journal=IEEE Transactions on Industry Applications |volume=37 |issue=5 |pages=1531–1536 |doi=10.1109/28.952531 }}</ref> which can be from a bad lamp or ballast or poor connection.

New fluorescent lamps may show a twisting spiral pattern of light in a part of the lamp. This effect is due to loose cathode material and usually disappears after a few hours of operation.{{r|GE1978|p=22}}
[[File:Fluorescent beat effect.ogv|thumb|right|The "beat effect" problem created when shooting films under standard fluorescent lighting]]
Electromagnetic ballasts may also cause problems for video recording as there can be a so-called ''[[beat (acoustics)|beat]] effect'' between the video frame rate and the fluctuations in intensity of the fluorescent lamp.

Fluorescent lamps with electronic ballasts do not flicker, since above about 5&nbsp;kHz, the excited electron state half-life is longer than a half cycle,{{Citation needed|date=November 2012}} and light production becomes continuous. Operating frequencies of electronic ballasts are selected to avoid interference with infrared remote controls. Poor quality or faulty electronic ballasts may have considerable 100/120&nbsp;Hz modulation of the light.