Question 35: NCERT Solutions for 12th Class Physics: Chapter 11-Dual Nature of Radiation and Matter
Find the typical de-Broglie wavelength associated with a He atom in helium gas at room temperature (27°C) and 1 atm pressure; and compare it with the mean separation between two atoms under these conditions.
Solution:

Let us first find mass ‘in’ of each helium atom.
Wavelength of the wave associated with He atom at room.temperature
Now let us find mean separation between He atoms. mean separation,
Comparing the wavelength ‘X’ with mean separation V, it can be observed that separa¬tion is larger than
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NCERT Solutions for 12th Class Physics: Chapter 11-Dual Nature of Radiation and Matter