Talk:Benham's top

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Related?[edit]

A horizontal black line on a white page has a violet top and a red bottom, when observed by a person pointing their nose down and while wearing high-index lenses. -- Sy / (talk) 16:43, 22 Jan 2005 (UTC)

Nope. This is due to the optical dispersion of the lens you're looking through...think of it as a very weak prism. Being so weak. only one edge or the other of the spectrum can be resolved, because it intrudes into the black line. The rest is swamped by the nearby white. Of course, Goethe seems to have thought that the interplay between darkness and light was responsible for the workings of prisms. I wonder if his theory of color would apply better to Benham's disk than Newton's theory does.--67.101.145.47 (talk) 04:27, 27 April 2009 (UTC)

Animated GIF?[edit]

Maybe someone could provide an animated gif showing this, preferable of the disk stationary, then speeding up, then slowing to staionary again, but looped.70.27.162.108 14:21, 18 September 2006 (UTC)

Done as of December 2009 [1] (click above the image to show the animation). --JonnyJD (talk) 11:51, 16 November 2013 (UTC)

Modern research?[edit]

Is there any modern research? I understand spinning tops and waving hands were the original means of illustrating the effect, but the given current explanations in literature (as far as I am able to find them) seem conflicted between temporal origin, spatial origin, or combination of both. The spinning disk would have both spatial and temporal components. It would seem like a relatively simple experiment to modulate a white LED in order to eliminate spatial effects (i.e. a sequence of on and off states), but I find no papers or references that try to reproduce the effect by modulating a spatially uniform piece of paper lit by a flickering LED. A modulated LED would be more reliable than modulating a screen pixel, since the response time of an LED is many orders of magnitude faster than the response time of screen pixels... — Preceding unsigned comment added by 77.109.97.84 (talk) 12:52, 26 November 2017 (UTC)

original research - relation to fluorescent light[edit]

unfortunately, i can't add this information to the article, because it's based on original research (done by some highschool students, and reported to me verbally), but it might shed some light (pun intended) on the phenomenon.

to observe the phenomenon i'm talking about, prepare such top, and use it under natural light, and under fluorescent light. you'll find that it is significantly more pronounced under fluorescent light. you may want to experiment with various light sources, such as LED, incandescent, etc. note that there may be some diff between LED fed of the main (typically AC at 50 or 60 hertz in most countries), and flashlight (DC).

the explanation when using fluorescent light (AC) is surprisingly simple and trivial: even though the light is "white", it turns out that the different color components of the light are not 100% synchronized: over one cycle of the AC, the R, G, and B components, show slightly different timing, so (for instance), the red component may starts earlier, which means that at the beginning of the cycle, the light is "reddish", and similarly, the G and B components are not fully synchronized. once one realizes that, it is trivial to understand the effect, at least for fluorescent light. for natural (or non-alternating) light there must be other explanations.

some information can be found here: [2]. specifically, notice the paragraph

Less well-known is the chromatic modulation resulting from differential decay rates of light

emissions from the various phosphors used in fluorescent lamps. Some of the commonly-used phosphors that emit long-wavelength light continue to do so for some time after the gas discharge, whereas phosphors with greater emission at shorter wavelengths persist for a shorter time.(4) The longer persisting phosphors introduce a phase lag with the result that the light alternates in colour as well as intensity. The rate of chromatic flicker depends on the type of

ballast used to power the lamps and the persistence of the specific phosphors

peace - קיפודנחש (aka kipod) (talk) 21:47, 18 April 2018 (UTC)

Seizure warning innefective on page preview[edit]

When the page is seen through the page preview (as when one hovers this article's link from within Wikipedia) the animation plays unhindered. Maybe the animation could be repositioned as to not be the first thing the "preview maker" displays.--181.93.61.116 (talk) 04:49, 23 July 2018 (UTC)