Suppose, in certain conditions only those transitions are allowed to hydrogen atoms in which the principal quantum number n changes by 2.

(a) Find the smallest wavelength emitted by hydrogen.


(b) List the wavelengths emitted by hydrogen in the visible range (380 nm to 780 nm).


(a)Given: Quantum number n changes by 2.


And as we know that for minimum wavelength and from given condition


Now as per Einstein-Planck equation,


where and is wavelength.





(b)Since the obtained wavelength does not lie in visible range so we will take another transition possible that is from to


Again using,


where




Since this wavelength lies in the range between 380nm to 780nm so this is the wavelength emitted by hydrogen in the visible range.


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