John Henry Poynting
John Henry Poynting was an English
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...

A physicist is a scientist who studies or practices physics. Physicists study a wide range of physical phenomena in many branches of physics spanning all length scales: from sub-atomic particles of which all ordinary matter is made to the behavior of the material Universe as a whole...

. He was a professor
A professor is a scholarly teacher; the precise meaning of the term varies by country. Literally, professor derives from Latin as a "person who professes" being usually an expert in arts or sciences; a teacher of high rank...

 of physics
Physics is a natural science that involves the study of matter and its motion through spacetime, along with related concepts such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves.Physics is one of the oldest academic...

 at Mason Science College
Mason Science College
Mason Science College was founded by Josiah Mason in 1875, the buildings of which were opened in Edmund Street, Birmingham, England on 1 October 1880 by Thomas Henry Huxley...

 (now the University of Birmingham
University of Birmingham
The University of Birmingham is a British Redbrick university located in the city of Birmingham, England. It received its royal charter in 1900 as a successor to Birmingham Medical School and Mason Science College . Birmingham was the first Redbrick university to gain a charter and thus...

) from 1880 until his death.

Poynting was the youngest son of Thomas Elford Poynting, a Unitarian
Unitarianism is a Christian theological movement, named for its understanding of God as one person, in direct contrast to Trinitarianism which defines God as three persons coexisting consubstantially as one in being....

 minister. In his boyhood he was educated at a school operated by his father. From 1867 to 1872 he attended Owen's College, now the University of Manchester
University of Manchester
The University of Manchester is a public research university located in Manchester, United Kingdom. It is a "red brick" university and a member of the Russell Group of research-intensive British universities and the N8 Group...

, where his physics teachers included Osborne Reynolds
Osborne Reynolds
Osborne Reynolds FRS was a prominent innovator in the understanding of fluid dynamics. Separately, his studies of heat transfer between solids and fluids brought improvements in boiler and condenser design.-Life:...

 and Balfour Stewart
Balfour Stewart
Balfour Stewart was a Scottish physicist. His studies in the field of radiant heat led to him receiving the Rumford Medal of the Royal Society in 1868. In 1859 he was appointed director of Kew Observatory...

. From 1872 to 1876 he was a student at Cambridge University, where he attained high honours in mathematics after taking grinds with Edward Routh
Edward Routh
Edward John Routh FRS , was an English mathematician, noted as the outstanding coach of students preparing for the Mathematical Tripos examination of the University of Cambridge in its heyday in the middle of the nineteenth century...

. In the late 1870s he worked in the Cavendish Laboratory
Cavendish Laboratory
The Cavendish Laboratory is the Department of Physics at the University of Cambridge, and is part of the university's School of Physical Sciences. It was opened in 1874 as a teaching laboratory....

 at Cambridge under James Clerk Maxwell
James Clerk Maxwell
James Clerk Maxwell of Glenlair was a Scottish physicist and mathematician. His most prominent achievement was formulating classical electromagnetic theory. This united all previously unrelated observations, experiments and equations of electricity, magnetism and optics into a consistent theory...


He was the developer and eponym
An eponym is the name of a person or thing, whether real or fictitious, after which a particular place, tribe, era, discovery, or other item is named or thought to be named...

 of the Poynting vector
Poynting vector
In physics, the Poynting vector can be thought of as representing the directional energy flux density of an electromagnetic field. It is named after its inventor John Henry Poynting. Oliver Heaviside and Nikolay Umov independently co-invented the Poynting vector...

, which describes the direction and magnitude of electromagnetic
Electromagnetism is one of the four fundamental interactions in nature. The other three are the strong interaction, the weak interaction and gravitation...

 energy flow and is used in the Poynting theorem, a statement about energy conservation for electric
Electric field
In physics, an electric field surrounds electrically charged particles and time-varying magnetic fields. The electric field depicts the force exerted on other electrically charged objects by the electrically charged particle the field is surrounding...

 and magnetic
Magnetic field
A magnetic field is a mathematical description of the magnetic influence of electric currents and magnetic materials. The magnetic field at any given point is specified by both a direction and a magnitude ; as such it is a vector field.Technically, a magnetic field is a pseudo vector;...

 fields. This work was first published in 1884. He performed a measurement of Newton's
Isaac Newton
Sir Isaac Newton PRS was an English physicist, mathematician, astronomer, natural philosopher, alchemist, and theologian, who has been "considered by many to be the greatest and most influential scientist who ever lived."...

 gravitational constant
Gravitational constant
The gravitational constant, denoted G, is an empirical physical constant involved in the calculation of the gravitational attraction between objects with mass. It appears in Newton's law of universal gravitation and in Einstein's theory of general relativity. It is also known as the universal...

 by innovative means during 1893. In 1903 he was the first to realise that the Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...

's radiation can draw in small particles towards it: this was later named the Poynting-Robertson effect
Poynting-Robertson effect
The Poynting–Robertson effect, also known as Poynting–Robertson drag, named after John Henry Poynting and Howard Percy Robertson, is a process by which solar radiation causes a dust grain in the Solar System to slowly spiral into the sun...


Poynting and the Nobel prizewinner J. J. Thomson
J. J. Thomson
Sir Joseph John "J. J." Thomson, OM, FRS was a British physicist and Nobel laureate. He is credited for the discovery of the electron and of isotopes, and the invention of the mass spectrometer...

 coauthored a multi-volume undergraduate physics textbook, which was in print for about 50 years and was in widespread use during the first third of the twentieth century. Poynting wrote most of it.

Works by J. H. Poynting

Impact crater
In the broadest sense, the term impact crater can be applied to any depression, natural or manmade, resulting from the high velocity impact of a projectile with a larger body...

s on Mars
Mars is the fourth planet from the Sun in the Solar System. The planet is named after the Roman god of war, Mars. It is often described as the "Red Planet", as the iron oxide prevalent on its surface gives it a reddish appearance...

 and the Moon
Poynting (lunar crater)
Poynting is a large lunar impact crater located on the far side of the Moon. It is located to the north-northwest of the walled plain Hertzsprung, with the crater Fersman immediately to the east and Kekulé equally near to the west-southwest....

 are named in his honour, as is the main Physics building at the University of Birmingham
University of Birmingham
The University of Birmingham is a British Redbrick university located in the city of Birmingham, England. It received its royal charter in 1900 as a successor to Birmingham Medical School and Mason Science College . Birmingham was the first Redbrick university to gain a charter and thus...

 and the departmental society there, the Poynting Physical Society.

External links

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