If one ilumna effect mtal (electromagnetic radiation we shine upon him), q is podms obsrvar "tear" electrons, s DCIR are cast. Cn Podms vary the frequency of q-light radiation is incident and mdir energy and energy depndencia the frequency cn. Exprimntalmnt observed the following facts: There is a threshold frequency, + d down which no electronesEl No. Emitn q d electrons are emitted, once beyond that threshold frequency, is proportional wing d the incident radiation intensity, energy xola electrons GOD emitidosno . incertidu: claims that can not be determined simultaneously with arbitrary precision, certain pairs of physical variables, such as, for example, the position and momentum of a given object. Simply put, the more certain is sought in determining the position of a particle, less is known about its linear momentum. Aclosed orbit is the path q dl describes the electron around the nucleus. An orbital is a region of space in the q and q can move the electron is described by a wave function.