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Photoelectric Effect and Derivation



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Here you can find all types notes by handwritten.
Here,we are providing physics photoelectric
effect,which is most useful in your semester exam.This topic is totally designed according to our syllabus.
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Einstein's photoelectric equation.
According to Einstein, the emission of photoelectron is the result of the interaction between a single photon of the incident radiation and an electron in the metal.
When a photon of energy  is incident on a metal surface, its energy is used up in two ways.
(i) A part of the energy of the photon is used in extracting the electron from the surface of metal, since the electrons in the metal are bound to the nucleus. This energy  spent in releasing the photoelectron is known as photoelectric work function of the metal. The work function of a photo metal is defined as the minimum amount of energy required to liberate an electron from the metal surface.
(ii) The remaining energy of the photon is used to impart kinetic energy to the liberated electron. If  is the mass of an electron and  its velocity, then
Energy of the incident photon  Work function  Kinetic energy of the electron

If the electron does not lose energy by internal collisions, as it escapes from the metal, the entire energy  will be exhibited as the kinetic energy of the electron Thus,  represents the maximum kinetic energy of the ejected photoelectron. If Vman is the maximum velocity with which the photoelectron can be ejected, then

This equation is known as Einstein's photoelectric equation.
When the frequency  of the incident radiation is equal to the threshold frequency  of the metal surface, kinetic energy of the electron is zero. Then equation  becomes,

Substituting the value of  in equation  we get,

 (or) 
This is another form of Einstein's photoelectric equation.



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