Question

what transition in the Helium positive spectrum what have the same wavelength as the first lyman transition of hydrogen from second Orbit to first orbit​

Answer 1

Answer:

The He+ is a single electron system.The energy level of a system can be written as 

  E=R−h×n2Z2,

  where E=Energy of single atom.

               R-h=1.36ev

                 Z= atomic number,n=1 for H atom and z=2 for He+

                  n= principal quantum number.

   The first Lyman transistion of H has energy:

     E(H)=R−h×221−1E(He+)=R−h×22(221−421)

The electronic transistion will takes place fron n=4 to n=2,the He+

spectrum have same wavelength as first Lyman transistion