Derive Photoelectric Equation


KE MAX = HV – O

To prove the equation of photoelectrons, we'll start with the fundamental principles of the photoelectric effect.

 

1. Photon Energy:

   The energy E Photon of an incoming photon is

   Ephoton= hv

   where h is Planck's constant and v is the frequency of the photon.

 

2. Work Function:

   The work function o of a material is the minimum energy required to eject an electron from the surface of the material.

 

3. Photoelectric Effect:

   When a photon strikes the material, its energy is transferred to an electron. To eject an electron, the photon must provide at least as much energy as the work function. Any additional energy beyond this threshold is converted into the kinetic energy of the emitted electron.

 

4. Conservation of Energy:

   According to the conservation of energy, the total energy of the photon is used to overcome the work function and to impart kinetic energy to the electron. Therefore:

  E photon = o  +E kin

   Here, E kin  is the kinetic energy of the emitted electron.

 

5. Maximum Kinetic Energy:

   The maximum kinetic energy K.E max of the emitted electron occurs when the photon energy is just enough to overcome the work function, leaving the maximum possible energy for the electron's kinetic energy. Rearranging the energy conservation equation to solve for K.E MAX

E kin  = E PHOTONO

Substituting EPhoton  HV ,

KE MAX = HV – O

 

This equation, KE MAX = HV – O , shows that the maximum kinetic energy of the emitted photoelectron is the difference between the energy of the incident photon and the work function of the material.

Links:

1. Photoelectric effects and its significance


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