John Henry Poynting

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John Henry Poynting FRS (9 September 1852 – 30 March 1914) was an English physicist, known for the Poynting vector and Poynting's theorem.

Quotes[edit]

  • 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.
  • When we see the havoc wrought on a sea-wall by a storm, it is easy to believe that ocean waves exert a pressure against the shore on which they beat. But it is not easy to think that the tiny ripples of light also press against every body on which they fall, to think that when a lamp is lighted waves of pressure are sent out from it—pressing against the source from which they start, pressing against every surface which they illuminate. It is a very minute pressure, far too small, even when it is strongest, to be felt by our bodies, and only to be detected by exceeding sensitive apparatus.

Quotes about Poynting[edit]

  • The main influence on all of the activity in electromagnetic theory during the later years of the nineteenth century came from Maxwell's famous treatise (Maxwell 1873). Poynting was a member of the group of young physicists led by Heaviside, Fitzgerald, Lodge and Hertz who developed Maxwell's electromagnetic theory in the years following his death in 1879. They transformed his 1873 presentation into the formalism recognizable today as Maxwell's equations. The detailed historical accounts by Hunt (1991) and Warwick (2003) describe Poynting's contributions to electromagnetism, mainly during the 1880s. His name is more familiar to students of electromagnetic theory than those of other important members of the group on account of the widespread use of his eponymous energy-conservation theorem and energy-flow vector.
    • R. Loudon and C. Baxter: (2012). "Contributions of John Henry Poynting to the understanding of radiation pressure". Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 468 (2143): 1825-1838. DOI:10.1098/rspa.2011.0573.

External links[edit]

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