Albert Einstein

Albert Einstein(1879-1955) is a German-born US physicist, who took Swiss nationality in 1901. A year later he went to work in the Bern patent office. In 1905 he published five enormously influential papers, one on Brownian movement, one on the photoelectric effect, one on the special theory of relativity and one on energy and inertia (which included the famous expression E = mc²). In 1915 he published the general theory of relativity, concerned mainly with gravitation. In 1921 he was awarded the Nobel Prize for Physics. In 1933 as a Jew, Einstein decided to remain in the USA (where he was lecturing), as Hitler had come to power. For all his life he sought a unified field theory. In 1939 he informed President Roosevelt that an atom bomb was feasible and that Germany might be able to make one.

Einstein coefficientsare coefficients used in the quantum theory of radiation, related to the probability of a transition occurring between the ground state and an excited state (or vice versa) in the processes of induced emission and spontaneous emission. For an atom exposed to electromagnetic radiation, the rate of absorption R_a is given by R_a = Bp, where p is the density of electromagnetic radiation and В is the Einstein В coefficient associated with absorption. The rate of induced emission is also given by Bp, with the coefficient В of induced emission being equal to the coefficient of absorption. The rate of spontaneous emission is given by A, where A is the Einstein A coefficient of spontaneous emission. The A and В coefficients are related by A = 8πhv³B/c³, where h is the Planck constant, v is the frequency of electromagnetic radiation, and с is the speed of light. The coefficients were put forward by Albert Einstein in 1916-17 in his analysis of the quantum theory of radiation.

Einstein equation is the mass-energy relationship announced by Albert Einstein in 1905 in the form E = mc², where E is a quantity of energy, m its mass, and с is the speed of light. It presents the concept that energy possesses mass. The relationship E_max = hf - W, where E_max is the maximum kinetic energy of electrons emitted in the photoemissive effect, h is the Planck constant, ¦ is the frequency of the incident radiation, and W is the work function of the emitter. This is also written E_max = hf - φе, where e is the electronic charge and φ is a potential difference, also called the work function. (Sometimes W and φ are distinguished as work function energy and work function potential.) The equation can also be applied to photoemission from gases, when it has the form: E = hf - I, where I is the ionization potential of the gas.

<== попередня сторінка	\|	наступна сторінка ==>
Hammett equation	\|	МЕТОДИЧНІ РЕКОМЕНДАЦІЇ ДЛЯ ВИКОНАННЯ РОБОТИ

Не знайшли потрібну інформацію? Скористайтесь пошуком google:

Генерація сторінки за: 0.005 сек.