John Henry Poynting

Quotes

• “A very simple experiment shows that a black surface is a better radiator, or pours out more energy when hot, than a surface which does not absorb fully, but reflects much of the radiation which falls upon it. If a platinum foil with some black marks on it be heated to redness, the marks, black when cold, are much brighter than the surrounding metal when hot; they are, in fact, pouring out much more visible radiation than the metal.”
• “The Earth, then, is very round. If an exact model were made the size of a two-inch billiard ball, we should just be able to see that it was flatter at the poles, and, no doubt, in rolling it would exhibit its want of roundness. The highest mountains would be represented by elevations of \frac {1} {800}th inch, say by the thinnest smear of grease, the deepest oceans by the spreading of a drop into a film but \frac {1} {700}th inch thick.”

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Key facts

Born

( 1852-09-09 ) 9 September 1852, Monton , Lancashire, England

Died

30 March 1914 (1914-03-30) (aged 61), Birmingham , England

Alma mater

University of Cambridge Owens College (now University of Manchester )

Known for

Poynting vector , Poynting effect , Poynting's theorem , Poynting–Robertson effect , Term " Greenhouse Effect ", Calculating the mass of the Earth

Awards

Adams Prize (1893) Hopkins Prize (1893) Royal Medal (1905)

Fields

Physicist

Institutions

Mason Science College , University of Birmingham

Academic advisors

James Clerk Maxwell

Notable students

Francis William Aston ; Alfred J. Lotka

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Wikidata facts

Image

John Henry Poynting.jpg

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