Ibn Sahl

Ibn Sahl (Arabic: ابن سهل‎) (Abu Saʿd al-ʿAlaʾ ibn Sahl ) (Arabic: أبو سعد العلاء ابن سهل‎) (c. 940–1000) was a Muslim mathematician, physicist and optics engineer of the Islamic Golden Age associated with the Abbasid court of Baghdad. Ibn Sahl's 984 treatise On Burning Mirrors and Lenses sets out his understanding of how curved mirrors and lenses bend and focus light. Ibn Sahl is credited with first discovering the law of refraction, usually called Snell's law. He used the law of refraction to derive lens shapes that focus light with no geometric aberrations, known as anaclastic lenses.

In the reproduction of the figure from Ibn Sahl's manuscript, the critical part is the right-angled triangle. The inner hypotenuse shows the path of an incident ray and the outer hypotenuse shows an extension of the path of the refracted ray if the incident ray met a crystal whose face is vertical at the point where the two hypotenuses intersect. According to Roshdi Rashed, an author and historian of medieval science and mathematics, the ratio of the length of the smaller hypotenuse to the larger is the reciprocal of the refractive index of the crystal.

Ibn Sahl (disambiguation)

Ibn Sahl may refer to:

IBN

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In communications and media

Patronymic

A patronym, or patronymic, is a component of a personal name based on the given name of one's father, grandfather, or an even-earlier male ancestor. A component of a name based on the name of one's mother or a female ancestor is a matronymic. Each is a means of conveying lineage.

Patronymics are still in use, including mandatory use, in many places worldwide, although their use has largely been replaced by or transformed into patronymic surnames.

History

In many areas around the world, patronyms predate the use of family names. Family names in many Celtic, English, Iberian, Scandinavian, Armenian and Slavic surnames originate from patronyms, e.g. Wilson (son of William), Powell (from "ap Hywel"), Fernández (son of Fernando), Rodríguez (son of Rodrigo), Carlsson (son of Carl), Ilyin (of Ilya), Petrov (of Peter), Stefanović (son of Stefan, little Stefan) and O'Connor (from "Ó Conchobhair", meaning grandson/descendant of Conchobhar). Other cultures which formerly used patronyms have switched to the more widespread style of passing the father's last name to the children (and wife) as their own.

IBN-7

IBN-7 (originally Channel 7 from 2006 to 2009) is an Indian cable and satellite news television channel, which is owned by TV18. The channel was launched on 15 August 2006 with the tagline "khabar, har keemat par" (English: "News, at any cost"). On 19 October 2014, the channel was relaunched with the new tagline "Hausla Hai", with a fresh and positive perspective, a committed team of reporters, new shows and pacier & cleaner graphics.

In February 2015, IBN-7 was marked its position in the top three Hindi news television channels as per the latest TGI survey.

See also

Competitors

References

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