![Disque newton](https://upload.wikimedia.org/wikipedia/commons/c/c9/Disque_newton.png)
The Newton disc, also known as the Disappearing Colour Disc, is a well-known physics experiment with a rotating disc with segments in different
color
Color (American English) or colour (British English) is the visual perceptual property deriving from the spectrum of light interacting with the photoreceptor cells of the eyes. Color categories and physical specifications of color are associ ...
s (usually Newton's
primary color
A set (mathematics), set of primary colors or primary colours (see American and British English spelling differences#-our, -or, spelling differences) consists of colorants or colored lights that can be mixed in varying amounts to produce a gamu ...
s: red, orange, yellow, green, blue, indigo, and violet or
ROYGBIV
ROYGBIV is an acronym for the sequence of hues commonly described as making up a rainbow: red, orange, yellow, green, blue, indigo, and violet. There are several mnemonics that can be used for remembering this color sequence, such as the ...
) appearing as white (or off-white or gray) when it spins very fast.
This type of mix of light stimuli is called temporal optical mixing, a version of
additive-averaging mixing. The concept that human
visual perception
Visual perception is the ability to interpret the surrounding environment through photopic vision (daytime vision), color vision, scotopic vision (night vision), and mesopic vision (twilight vision), using light in the visible spectrum reflecte ...
cannot distinguish details of high-speed movements is popularly known as
persistence of vision
Persistence of vision traditionally refers to the optical illusion that occurs when visual perception of an object does not cease for some time after the rays of light proceeding from it have ceased to enter the eye.
The illusion has also been d ...
.
The disc is named after
Isaac Newton
Sir Isaac Newton (25 December 1642 – 20 March 1726/27) was an English mathematician, physicist, astronomer, alchemist, theologian, and author (described in his time as a "natural philosopher"), widely recognised as one of the grea ...
. Although he published a circular diagram with segments for the primary colors that he had discovered, it is uncertain whether he actually ever used a spinning disc to demonstrate the principles of
light
Light or visible light is electromagnetic radiation that can be perceived by the human eye. Visible light is usually defined as having wavelengths in the range of 400–700 nanometres (nm), corresponding to frequencies of 750–420 tera ...
.
Transparent variations for
magic lantern
The magic lantern, also known by its Latin name , is an early type of image projector that used pictures—paintings, prints, or photographs—on transparent plates (usually made of glass), one or more lenses, and a light source. Because a si ...
projection have been produced.
History
Around 165 CE,
Ptolemy
Claudius Ptolemy (; grc-gre, Πτολεμαῖος, ; la, Claudius Ptolemaeus; AD) was a mathematician, astronomer, astrologer, geographer, and music theorist, who wrote about a dozen scientific treatises, three of which were of importanc ...
described in his book ''
Optics
Optics is the branch of physics that studies the behaviour and properties of light, including its interactions with matter and the construction of instruments that use or detect it. Optics usually describes the behaviour of visible, ultraviole ...
'' a rotating potter's wheel with different colors on it. He noted how the different colors of sectors mixed together into one color and how dots appeared as circles when the wheel was spinning very fast. When lines are drawn across the axis of the disc they make the whole surface appear to be of a uniform color. "The visual impression that is created in the first revolution is invariably followed by repeated instances that subsequently produce an identical impression. This also happens in the case of shooting stars, whose light seems distended on account of their speed of motion, all according to the amount of perceptible distance it passes along with the sensible impression that arises in the visual faculty."
Porphyry ( – ) wrote in his commentary on Ptolemy's ''Harmonics'' how the senses are not stable but confused and inaccurate. Certain intervals between repeated impressions are not detected. A white or black spot on a spinning cone (or top) appears as a circle of that color and a line on the top makes the whole surface appear in that color. "Because of the swiftness of the movement we receive the impression of the line on every part of the cone as the line moves."
in the 11th century
Ibn al-Haytham
Ḥasan Ibn al-Haytham, Latinized as Alhazen (; full name ; ), was a medieval mathematician, astronomer, and physicist of the Islamic Golden Age from present-day Iraq.For the description of his main fields, see e.g. ("He is one of the prin ...
, who was familiar with Ptolemy's writings, described how colored lines on a spinning top could not be discerned as different colors but appeared as one new color composed of all of the colors of the lines. He deducted that sight needs some time to discern a color. al-Haytam also noted that the top appeared motionless when spun extremely quick "for none of its points remains fixed in the same spot for any perceptible time".
After
Ibn al-Haytham
Ḥasan Ibn al-Haytham, Latinized as Alhazen (; full name ; ), was a medieval mathematician, astronomer, and physicist of the Islamic Golden Age from present-day Iraq.For the description of his main fields, see e.g. ("He is one of the prin ...
, Fakhr al-Din al-Razi (d. 1209) performed the spinning disk experiment, and like his predecessors he concluded that it shows an optical illusion. However, the famous astronomer-mathematician Nasir al-Din al-Tusi described al-Razi's text and arrived at a very different conclusion. Tusi introduced a common sense organ that forwards color impressions to the soul. When colors change too fast, this organ can only pass on the mixed color. One of Tusi's students was Qutb al-Din al-Shirazi (d.1311), and together with his own brilliant student Kamal al-Din al-Farisi he tried to explain the colors perceived in the experiment.
Newton's primary colours
On 16 February 1672(6 February 1671 old style), Isaac Newton sent a paper to the Royal Society's journal ''Philosophical Transactions'', about the experiments he had been conducting since 1666 with the
refraction
In physics, refraction is the redirection of a wave as it passes from one medium to another. The redirection can be caused by the wave's change in speed or by a change in the medium. Refraction of light is the most commonly observed phenomeno ...
of light through glass prisms. He concluded that the different refracted rays of light – well parted from others – could not be changed by further refraction, nor by reflection or other means, except through mixture with other rays. He thus found the seven primary colors red, orange, yellow, green, blue, "a violet-purple" and indigo. When mixing the coloured rays from a prism, he found that "the most surprising and wonderful composition was that of whiteness" requiring all the primary colors "mixed in a due proportion".
In reaction to
Robert Hooke
Robert Hooke FRS (; 18 July 16353 March 1703) was an English polymath active as a scientist, natural philosopher and architect, who is credited to be one of two scientists to discover microorganisms in 1665 using a compound microscope that ...
's criticism of the new theory of light, Newton published a letter in the ''Philosophical Transactions'', with other experiments that proved how sunlight existed of rays with different colours. He described how the cogs or teeth of a gyrating wheel behind a prism can block part of the light so that all the colours would be projected successively if the wheel turns rather slow, but how all the colours will be mixed into white light if the wheel turn very fast. He also pointed out that rays of light that were reflected from multi-coloured bodies were weakened by the loss of many rays and that a mixture of those rays would not produce a pure white, but a gray or "dirty" colour. This could be seen in dust, which on close inspection would reveal that it consists of many coloured particles, or when mixing several colours of paint. He also referred to a child's top which would display a "dirty" colour if it was painted in several colours and made to spin fast by whipping it.
After presenting his conclusions about dividing sunlight into primary colors and mixing them back together into white light, Newton presented a
color circle
A color wheel or color circle is an abstract illustrative organization of color hues around a circle, which shows the relationships between primary colors, secondary colors, tertiary colors etc.
Some sources use the terms ''color wheel'' & ' ...
to illustrate the relations between these colors in his book ''
Opticks
''Opticks: or, A Treatise of the Reflexions, Refractions, Inflexions and Colours of Light'' is a book by English natural philosopher Isaac Newton that was published in English in 1704 (a scholarly Latin translation appeared in 1706). (''Optick ...
'' (1704).
Many modern sources state that Isaac Newton himself used a spinning disc with colored sectors to demonstrate how white light was actually the compound of the primary colors. However, these do not reference any historical source.
According to
Joseph Plateau
Joseph Antoine Ferdinand Plateau (14 October 1801 – 15 September 1883) was a Belgian physicist and mathematician. He was one of the first people to demonstrate the illusion of a moving image. To do this, he used counterrotating disks with repea ...
, the first to describe how a spinning disc with Newton's seven primary colours would show an (imperfect) white colour was
Pieter van Musschenbroek
Pieter van Musschenbroek (14 March 1692 – 19 September 1761) was a Dutch scientist. He was a professor in Duisburg, Utrecht, and Leiden, where he held positions in mathematics, philosophy, medicine, and astronomy. He is credited with the inven ...
in 1762.
See also
*
Benham's top
References
External links
*
{{DEFAULTSORT:Newton Disc
Isaac Newton
Color