Does the word quantum mechanics mean anything to you, well it should. What about E=MC2, all of this are very important to you but you may not know it. These theories were all developed by a very intellectual person, Albert Einstein. Albert Einstein is very important to the development of our country and the world.
Albert Einstein started his life in Ulm, Germany, march 14, 1879. Einstein’s parents were nonobservant Jews. They moved from Ulm to Munich when Albert was an infant. They had a family business of the manufacture of electrical apparatus. The company failed in 1894. So the family moved to Milan, Italy. At this time Albert had decided to give up his German citizenship. Without even finishing secondary school he went to take a test that would have allowed him to pursue a course of study that would have lead to a diplomat the Swiss Federal Institute of technology in electrical engineering. So after this he went back to secondary school and finished. In his spare time he wrote about theoretical physics. In 1905 he received his Ph.D. In 1908 he sent a paper to the University of Bern and became privatdocent or a lecture there. By the time 1909 Albert was recognized throughout Europe as a leading scientific thinker. By 1914 he advanced to the prestigious and beast paying post that a theoretical physicist could hold in Europe. He continued to teach until 1955 when he died in Princeton, NJ This is one reason that clearly proves that he was important to the education of future generations.
Albert contributed to many great inventions. His most famous was his epuation E=MC2. It states that energy and mass are equivalent, this is a concept that enabled scientists to undestand the energy sourse of the sun and other stars and led to the development of nuclear energy. The equation states that a mass m can theoretically be transformed into an amount of energy e , equal to m multiplied by the square of the speed of light. The speed of light is 3 x 1010 cm/sec. This concept first appeared in a paper he published in 1907.
Photoelectric effect is the release of electrons from certain metals or semiconductors by the action of light or other electromagnetic radiation. there are three different photoelectric effects. They are photoemissive, the photoconductive, and the photovoltaic.
Photoemissive effect, is radiant energy striking the prepared surface of a metal such as cesium imparts sufficiant energy to the electrons so that they are emitted into space. In a photoelectric cell the emitted electrons are collected by a positive electrod. Under the influence of a applyed voltage the create an electric current.
The photoconductive effect is that light changes the electrical conductivity of a material. In semiconductors most of the electrons are fixed in the valence bonds of the atoms but a few electrons with higher energies will have broken bonds and will be free to serve as mobile charges in conduction. The energy needed to break the bond is called the gap energy. One very usefull way that we use photoconductive cells are to automatically turn on and off streetlights and to dim automobile headlights.
In the photovolataic effect the light energy is applied to the junction region of a semiconductor diode. The photons break electron bonds in the junction region creating free electrons. The free electrons migrate to the two sides of the junction and increase the density there and raise the junction voltage. The photovoltaic cell is unique because it takes light and converts it directly to energy. No external voltage is needed. This type of cell is called a solar cell.
