Planck's Quantum Theory and Black Body Radiation
Explore the concepts behind Planck's quantum theory and black body radiation, including the quantization of energies, the nature of electromagnetic radiation, and the dual nature of Planck's equation. Learn about the relationship between mass-energy equivalence and the significance of Planck's constant in modern physics.
Download Presentation
Please find below an Image/Link to download the presentation.
The content on the website is provided AS IS for your information and personal use only. It may not be sold, licensed, or shared on other websites without obtaining consent from the author. If you encounter any issues during the download, it is possible that the publisher has removed the file from their server.
You are allowed to download the files provided on this website for personal or commercial use, subject to the condition that they are used lawfully. All files are the property of their respective owners.
The content on the website is provided AS IS for your information and personal use only. It may not be sold, licensed, or shared on other websites without obtaining consent from the author.
E N D
Presentation Transcript
PLANCKS QUANTUM THEORY Mrs.A.Mumthaj, M.Sc.,M.Phil., Asst.Prof. in Department of Chemistry, Hajee Karutha Rowther Howdia College , Uthamapalayam.
Black body : Radiation which is falling on the body will undergo below mentioned actions. i) Reflection ii) Absorption iii) Transmission A black body is an idealized physical body that absorbs all incident EMR, regardless of frequency or angle of incidence. 1. When temperature raises then the surrounding black body emits the radiation of all wavelength. Such radiation is known as black body radiation. 2. Example for black body emission is sun. 3. Example for black body absorption is carbon black .
Max Planck in 1901 proposed the vibrational energies of bodies are quantized. E = nh E = Energy of the photon = frequency of radiation h = planck s constant ( 6.626X10-34 Js ) Energy is quantised at the tiniest scale so we are not usually observed.
n is an integer ( n =1, 2, 3 . ) The minimum energy that the body given out is called the quantum. If n =1, i.e., the minimum energy of quantization and energy given out can only be multiples of this it cannot be continuous. Hence Scientists accepted the fact that EMR should have particle like nature ( quantized ) because waves are continuous. Planck EMR has dual nature i.e., wave and particle.
Planck constant value : In 1905, Einstein said that light energy having tiny particles ( proven ). According to him, the mass- energy equivalence is expressed as E = mc2 -------- 1 Einstein s relational expressions regarding light quanta are expressed by E = h ---------- 2 (Max Planck eqn, this was proved by Einstein through photoelectric effect in 1905) E = pc --------- 3 We consider the case in which all the rest mass energy of a single electron Currently at rest in free space is emitted as one photon.
Equate 1 & 2 mec2 = h me = mass of the electron or photon in free space c = velocity of photon particle mec2= hc/ c c = compton wavelength of the electron The above eqn becomes, mec = h/ c h = mec c me = 9.1 X 10-31 Kg c = 2.99 X 108 m/s c = 2.42 X 10-12 m h = 6.626 X 10-34 Js
References : 1. A.K. Chandra, Introductory Quantum Chemistry, Tata McGraw Hill Publishing Co., New Delhi,1988. 2. D. A. Mc Quarrie, Quantum Chemistry, 1st Indian editon, Viva Books Pvt Ltd, New Delhi, 2003.
