So friends, let's get started friends when light energy in the form of photons ( A photons is a tiny particle that comprises waves of Electromagnetic Radiation.) or particles strikes a metal piece with sufficient energy then electrons are ejected or emitted from the surface of the metal this effect is known as photoelectric effect or photoelectric emission now let's see how this happens a figure is shown here where a metallic piece is taken also a source of light is present over here when light is allowed to incident on the surface of the metal then electrons from the surface of the metal gets ejected fine these electrons are known as photo electrons because these are ejected by the action of photons now the question arises that light of any energy can eject the photo electrons from the surface of the metal so, the answer to this question is no basically each metal has a certain work function this work function is nothing but the minimum energy which is required by the electrons present in the surface of the metal to get ejected from its surface. So friends I hope you understand something about basic in Photoelectric effect now let's discuss further more
Photons:
A photons is a tiny particle that comprises waves of Electromagnetic Radiation. Photons doesn't have a charge , no mass, and photons are travel at the speed of light. Even though photons have no mass, they have momentum. Photons are often described as Energy packets. A photons , also called light quantum, is a minute energy packet of Electromagnetic Radiation. The energy of the photons of all energies from high- energy gamma rays and x- rays, through visible light, to low- energy infrared and radio waves.
Energy of a photon (or) Quantum energy:
E= hv = hc/λ
Where,
h is planck's constant
v is frequency of radiation
c is velocity of light
λ is wavelength of radiation
Photoelectric effect:
Photoelectric effect, when radiation of sufficient energy ( such as x-rays , Gamma rays, UV rays etc..,) incident on some meterial ( mostly metals) electrons are emitted. This phenomenon is known as Photoelectric effect. This effect was discovered by Heinrich Hertz in the year 1887.
 |
| Image source:Wikimedia |
Laws of Photoelectric effect
- For a given photosensitive material, there is a minimum frequency called threshold frequency (Vo) , above which there is photoelectric Emission and below which there is no photoelectric Emission, however great the intensity may be.
- For a given photosensitive material, the photoelectric current is directly proportional to the intensity of the incident radiation, provided the frequency is greater than the the threshold frequency (Vo).
- The photoelectric Emission is an Instantaneous process. There is no time lag between the incidence of radiation and the emission of photo electron.
- The maximum Kinetic energy of the Photoelectrons is directly proportional to the frequency of the incident radiation, and is independent of its intensity.
