Question

The wavelength for n=3 to n=2 transition of the hydrogen atom is 656.3 nm. What are the wavelength for this same transition in (a) positronium, which consists of an electron and a positron (b) singly ionized helium

Answer 1

Correct Answer - A::B::C::D
(a) Reduced mass of positronium and electron is `(m)/(2),`
where, m = mass of electron
`E prop m :. lambda prop (1)/(m)`
m has become half, so `lambda` will become two
times or 1312 nm or `1.31 mum.`
. For singly ionixed helium atom Z =2
`:. lambda is (1)/(4) th or 164 nm`