A stationary hydrogen atom emits a photon corresponding to first line of the Lyman series. What velocity does the atom acquire?

Answer

`(E)/(c ).(1)/(m)=(13.6xx3e)/(4cm_(p))=3.25m//s`

Explanation

Energy of the first line in Lyman series
`E=13.6xx(1-(1)/(4))eV=10.2 eV`
Velocity of atoms `=(p)/(m)=(E)/(c ).(1)/(m)=(10.2xx1.6xx10^(-19))/(3xx10^(8)xx1.67xx10^(-24))m//s=3.25 m//s`