In 1900, the German physicist Max Planck was studying black - body radiation and suggested that the energy carried by electromagnetic waves could only be released in "packets '' of energy. In his 1901 article in Annalen der Physik he called these packets "energy elements ''. The word quanta (singular quantum, Latin for how much) was used before 1900 to mean particles or amounts of different quantities, including electricity. In 1905, Albert Einstein suggested that electromagnetic waves could only exist as discrete wave - packets. He called such a wave - packet the light quantum (German: das Lichtquant). The name photon derives from the Greek word for light, φῶς (transliterated phôs). Arthur Compton used photon in 1928, referring to Gilbert N. Lewis. The same name was used earlier, by the American physicist and psychologist Leonard T. Troland, who coined the word in 1916, in 1921 by the Irish physicist John Joly, in 1924 by the French physiologist René Wurmser (1890 - 1993) and in 1926 by the French physicist Frithiof Wolfers (1891 - 1971). The name was suggested initially as a unit related to the illumination of the eye and the resulting sensation of light and was used later in a physiological context. Although Wolfers 's and Lewis 's theories were contradicted by many experiments and never accepted, the new name was adopted very soon by most physicists after Compton used it.
who introduced the term photon to represent a packet of light energy
Leonard T. Troland