Skip to main content

Einstein explanation of Photoelectric Effect.

 Einstein Explanation of Photoelectric Effect:

  • According to Einstein, electromagnetic radiation of frequency 𝛎 consist of photons, each of energy h𝛎.
  • When a photon of energy h𝛎 is incident on the surface of material, some of its energy is spent in making the electron free and the rest appears as kinetic energy of electron.
  • The electrons at the surface of the material are most loosely bound and require minimum energy for their liberation.
  • This energy is called the work function 𝛟 of material.
  • The maximum kinetic energy of photoelectrons, ejected from the surface is given by;  K.Eₘₐₓ= h𝛎 - 𝛟 
  • The electrons which are tightly bound are ejected with less kinetic energy.
  • Thus the kinetic energy of electron depends on the fact whether it is on the surface of material or it is deeper inside the material.
  • If  𝛎₀ is the frequency of incident radiation such that the photon energy h𝛎₀ is just sufficient to make the electron free from the material, then the ejected electron has zero kinetic energy. This happens when; h𝛎₀= 𝛟 
  • The frequency 𝛎₀ is threshold or cut off frequency and corresponding wavelength 𝛌₀ is called threshold wavelength.
  • Thus threshold frequency is the measure of work function of the material.
  • In terms of photon frequency 𝛎 and threshold frequency 𝛎₀ , Einstein Photoelectric equation can be written as        K.Eₘₐₓ= h𝛎 - h𝛎₀ => K.Eₘₐₓ= h(𝛎 - 𝛎₀) 
  • If V₀ is the stopping potential corresponding to incident radiation then; K.Eₘₐₓ= h(𝛎 - 𝛎₀) = eV₀  

Work function

The minimum energy (𝛟) required to eject an electron from a particular metal surface, is called work function of that metal.

Questions;

Q1) What is the relation between maximum kinetic energy and work function?
Ans)The maximum kinetic energy of photoelectrons, ejected from the surface is given by;  K.Eₘₐₓ= h𝛎 - 𝛟 . Where 𝛟 is work function.
Q2) What is work function?
Ans)The minimum energy (𝛟) required to eject an electron from a particular metal surface, is called work function of that metal.
Q3) Work function is denoted by which symbol?
Ans) 𝛟(phi).
Q4) Fill in the blanks
1)The electrons at the surface of the material are most loosely bound and require ------------ energy for their liberation.
2)The electrons which are tightly bound are ejected with --------- kinetic energy.
3)Thus the ---------- of electron depends on the fact whether it is on the surface of material or it is deeper inside the material.
4)In terms of photon frequency 𝛎 and threshold frequency 𝛎₀ , Einstein Photoelectric equation can be written as ----.
5)The minimum energy (𝛟) required to eject an electron from a particular metal surface, is called ---------- of that metal.
6)When a photon of energy h𝛎 is incident on the surface of material, some of its energy is spent in making the electron ------and the rest appears as --------- of electron.
Ans) 1)The electrons at the surface of the material are most loosely bound and require minimum energy for their liberation.
2)The electrons which are tightly bound are ejected with less kinetic energy.
3)Thus the kinetic energy of electron depends on the fact whether it is on the surface of material or it is deeper inside the material.
4)In terms of photon frequency 𝛎 and threshold frequency 𝛎₀ , Einstein Photoelectric equation can be written as        K.Eₘₐₓ= h𝛎 - h𝛎₀ => K.Eₘₐₓ= h(𝛎 - 𝛎₀) .
5)The minimum energy (𝛟) required to eject an electron from a particular metal surface, is called work function of that metal.
6)When a photon of energy h𝛎 is incident on the surface of material, some of its energy is spent in making the electron free and the rest appears as kinetic energy of electron.

Comments

Post a Comment

Popular posts from this blog

LS coupling and jj coupling.

 Total angular momentum: The total angular momentum of an electron is the sum of the orbital angular momentum and spin angular momentum of the electron i.e Coupling Scheme Since an atom consist of large number of electrons having different orbital and spin momenta, Coupling scheme is necessary to obtain the resultant orbit and spin momenta of atom as a whole. There are two types of coupling scheme namely 1) LS Coupling 2) JJ Coupling. 1)LS Coupling: In this coupling the 'l' vectors of all electrons combine to form resultant 'L' vector and all the 's' vectors of these electrons combine to form resultant 'S' vector. Then the 'L' vector and 'S' vector undergoes vector addition to give resultant 'J' vector which represents the total angular momentum of an atom. Symbolically LS coupling is represented as This type of coupling is governed by the following principles: 1) All the three vectors (L,S and J vectors) are quantized. 2)L is an ...
Post a Comment
Read more

Different kinds of beta decay.

 Different kinds of beta decay 1) Negative beta decay process: When there is excess number of neutrons in the nucleus, the neutron is converted into proton with the emission of electron and antineutrino particle and this process is called negative beta decay process. Negative beta decay. 2) Positive beta decay process: When there is excess number of protons in the nucleus, the proton is converted into neutron with the emission of positron and neutrino particle and this process is called positive beta decay process. Positive beta decay. 3) Electron Capture: When there is excess number of protons in the nucleus, sometimes the nucleus will absorbed the nearby electrons in the nearest electron orbital emitting neutron and a neutrino and this process is called electron capture. Electron capture. 4) Inverse beta decay: Inverse beta decay. Thus such kind of reaction in which neutrinos are absorbed to create some sort of beta decay is called inverse beta decay. Inverse beta decay confirm t...
Post a Comment
Read more

Photoelectric effect.

 Photoelectric effect; The emission of electrons by a substance under the action of light is called Photoelectric effect. Photoelectric Effect. Experimental Setup: The phenomenon of photoelectric effect can be studied with the help of an apparatus shown in Figure below. Within an evacuated glass jacket two electrodes R and S are enclosed and the light radiation is allowed to enter the jacket through a quartz window. The radiation falls on electrode R, called cathode. The electrode S can be kept at desired (positive or negative) potential with respect to the cathode. A sensitive ammeter is put in the circuit to record current resulting from photoelectrons. The potential difference between the cathode and anode can be measured by voltmeter . Experimental Setup. Experimental observations The experimental observation of photoelectric effect may be summarised as follows; 1) Effect of Intensity of light on Photoelectric current; For a constant potential difference between the cathode ...
Post a Comment
Read more