Question

If the shortest wavelength in lyman series of hydrogen atom is a, then the longest wavelength in paschen series of he+ is :

Answer 1

The wave no. of any series is given by;



where 109678 is a constant,lets say = ;

and,the series starts from n1 to n2;

 

Here,x is the wavelength for the last line(shortest wavelength) in lyman series,

therefore,n​1=1 to n​2=(infinity)​;

    ​(1/x)=​​[(1/1) – ​(1/)]    =    ​(​1 - 0) = 

    ​  =​ 1/x              

 

For wavelength of first line of balmer series,

n​1=2 to n​2=3  ​;lets say the wavelength to be found be = ;​



Substituting the value