The angular momentum of an electron in a Bohr's orbit of `He^+` is `3.1652 xx 10^-34 kg-m^2//sec`. What is the wave number in terms of Rydberg constant `(R )` of the spectral line emitted when an electron falls this level to the first excited state.
`["Use" h = 6.626 xx 10^-34 Js]`.

Options

A. `3R_(H)`
B. `(5R_(H))/(9)`
C. `(3R_(H))/(9)`
D. `(8R_(H))/(9)`

Answer

B

Explanation

`mvr = (nh)/(2pi)` where `n = 3, bar(v) = R_(H)z^(2) [(1)/(n_(1)^(2))-(1)/(n_(2)^(2))]`