When a photon is emitted from an atom , the atom recils The kinetic energy of recoils and the energy of the photon come from the difference in energy between the state involved in the transition suppose a hydrogen atom change its state from `n = 3 to n = 2` calculate the fractional change in the wavelength of light emitted , due to the recoil

Answer

A

Explanation

Difference in energy in the transition from
`n=3` to `n=2` is `1.89 eV`.
Let recoil energy be E.
Then `m_0[V_2^2 -V_3^2]+E`
`=1.89 eV`
`=1.89 xx 1.6 xx 10^-19J`
:' `1/2 xx 9.1 xx 10^-31[(2187/2)^2-(2187/3)^2]+E`
`=3.024 xx 10^-19J`
implies `E=10^-9`